diff --git a/.gitignore b/.gitignore
index 76d65f17..162a9448 100644
--- a/.gitignore
+++ b/.gitignore
@@ -46,4 +46,7 @@ next-env.d.ts
 /data/
 
 # Local private data
-/local-data/
\ No newline at end of file
+/local-data/
+
+# Sibling repos
+/repos/
\ No newline at end of file
diff --git a/app/[locale]/login/page.tsx b/app/[locale]/login/page.tsx
index 53123ee7..31ec1213 100644
--- a/app/[locale]/login/page.tsx
+++ b/app/[locale]/login/page.tsx
@@ -733,9 +733,9 @@ export default function LoginPage() {
                     )}
                   </Button>
                 ) : oauthDiscoveryDone ? (
-                  <div className="p-3.5 bg-amber-500/10 border border-amber-500/20 rounded-xl flex items-start gap-2">
-                    <AlertCircle className="w-4 h-4 text-amber-700 dark:text-amber-400 flex-shrink-0 mt-0.5" />
-                    <p className="text-sm text-amber-700 dark:text-amber-400">
+                  <div className="p-3.5 bg-warning/10 border border-warning/20 rounded-xl flex items-start gap-2">
+                    <AlertCircle className="w-4 h-4 text-warning flex-shrink-0 mt-0.5" />
+                    <p className="text-sm text-warning">
                       {t("error.oauth_discovery_failed")}
                     </p>
                   </div>
@@ -941,9 +941,9 @@ export default function LoginPage() {
                 )}
 
                 {oauthEnabled && oauthDiscoveryDone && !oauthMetadata && (
-                  <div className="mt-2 p-3 bg-amber-500/10 border border-amber-500/20 rounded-xl flex items-start gap-2">
-                    <AlertCircle className="w-4 h-4 text-amber-700 dark:text-amber-400 flex-shrink-0 mt-0.5" />
-                    <p className="text-sm text-amber-700 dark:text-amber-400">
+                  <div className="mt-2 p-3 bg-warning/10 border border-warning/20 rounded-xl flex items-start gap-2">
+                    <AlertCircle className="w-4 h-4 text-warning flex-shrink-0 mt-0.5" />
+                    <p className="text-sm text-warning">
                       {t("error.oauth_discovery_failed")}
                     </p>
                   </div>
diff --git a/app/[locale]/settings/page.tsx b/app/[locale]/settings/page.tsx
index 11fd0c3a..28aaee0c 100644
--- a/app/[locale]/settings/page.tsx
+++ b/app/[locale]/settings/page.tsx
@@ -69,6 +69,7 @@ interface TabDef {
   label: string;
   icon: LucideIcon;
   group: TabGroup;
+  experimental?: boolean;
 }
 
 const tabIcons: Record<Tab, LucideIcon> = {
@@ -162,8 +163,8 @@ export default function SettingsPage() {
     { id: 'contacts', label: t('tabs.contacts'), icon: tabIcons.contacts, group: 'apps' },
     ...(supportsFiles ? [{ id: 'files' as Tab, label: t('tabs.files'), icon: tabIcons.files, group: 'apps' as TabGroup }] : []),
     ...(isFeatureEnabled('sidebarAppsEnabled') ? [{ id: 'sidebar_apps' as Tab, label: t('tabs.sidebar_apps'), icon: tabIcons.sidebar_apps, group: 'apps' as TabGroup }] : []),
-    ...(isFeatureEnabled('themesEnabled') ? [{ id: 'themes' as Tab, label: 'Themes', icon: tabIcons.themes, group: 'system' as TabGroup }] : []),
-    ...(isFeatureEnabled('pluginsEnabled') ? [{ id: 'plugins' as Tab, label: 'Plugins', icon: tabIcons.plugins, group: 'system' as TabGroup }] : []),
+    ...(isFeatureEnabled('themesEnabled') ? [{ id: 'themes' as Tab, label: 'Themes', icon: tabIcons.themes, group: 'system' as TabGroup, experimental: true }] : []),
+    ...(isFeatureEnabled('pluginsEnabled') ? [{ id: 'plugins' as Tab, label: 'Plugins', icon: tabIcons.plugins, group: 'system' as TabGroup, experimental: true }] : []),
     { id: 'advanced', label: t('tabs.advanced'), icon: tabIcons.advanced, group: 'system' },
   ];
 
@@ -290,6 +291,11 @@ export default function SettingsPage() {
                       <span className="flex items-center gap-3">
                         <Icon className="w-4 h-4 text-muted-foreground" />
                         {tab.label}
+                        {tab.experimental && (
+                          <span className="text-[10px] font-medium px-1.5 py-0.5 rounded-full bg-warning/15 text-warning">
+                            Experimental
+                          </span>
+                        )}
                       </span>
                       <ChevronRight className="w-4 h-4 text-muted-foreground" />
                     </button>
@@ -396,6 +402,11 @@ export default function SettingsPage() {
                         activeTab === tab.id ? 'text-accent-foreground' : 'text-muted-foreground'
                       )} />
                       {tab.label}
+                      {tab.experimental && (
+                        <span className="ml-auto text-[10px] font-medium px-1.5 py-0.5 rounded-full bg-warning/15 text-warning shrink-0">
+                          Experimental
+                        </span>
+                      )}
                     </button>
                   );
                 })}
diff --git a/app/admin/page.tsx b/app/admin/page.tsx
index 79b5359b..5b6c0538 100644
--- a/app/admin/page.tsx
+++ b/app/admin/page.tsx
@@ -105,18 +105,18 @@ export default function AdminDashboardPage() {
     <div className="max-w-3xl space-y-8">
       {/* Warnings */}
       {warnings.map((msg, i) => (
-        <div key={i} className="flex items-start gap-3 rounded-lg border border-amber-200 bg-amber-50 dark:border-amber-900 dark:bg-amber-950/30 p-4">
-          <AlertTriangle className="w-5 h-5 text-amber-600 dark:text-amber-400 mt-0.5 shrink-0" />
-          <p className="text-sm text-amber-700 dark:text-amber-300">{msg}</p>
+        <div key={i} className="flex items-start gap-3 rounded-lg border border-warning/20 bg-warning/10 p-4">
+          <AlertTriangle className="w-5 h-5 text-warning mt-0.5 shrink-0" />
+          <p className="text-sm text-warning">{msg}</p>
         </div>
       ))}
 
       {status && !status.lastLogin && (
-        <div className="flex items-start gap-3 rounded-lg border border-amber-200 bg-amber-50 dark:border-amber-900 dark:bg-amber-950/30 p-4">
-          <AlertTriangle className="w-5 h-5 text-amber-600 dark:text-amber-400 mt-0.5 shrink-0" />
+        <div className="flex items-start gap-3 rounded-lg border border-warning/20 bg-warning/10 p-4">
+          <AlertTriangle className="w-5 h-5 text-warning mt-0.5 shrink-0" />
           <div>
-            <p className="text-sm font-medium text-amber-800 dark:text-amber-200">First login detected</p>
-            <p className="text-sm text-amber-700 dark:text-amber-300 mt-0.5">
+            <p className="text-sm font-medium text-warning">First login detected</p>
+            <p className="text-sm text-warning/80 mt-0.5">
               Remember to remove ADMIN_PASSWORD from your .env file now that the hash is stored securely.
             </p>
           </div>
diff --git a/app/admin/plugins/page.tsx b/app/admin/plugins/page.tsx
index ace58673..db3a5523 100644
--- a/app/admin/plugins/page.tsx
+++ b/app/admin/plugins/page.tsx
@@ -252,8 +252,8 @@ export default function AdminPluginsPage() {
                 </div>
                 {plugin.permissions.length > 0 && (
                   <div className="flex items-center gap-1 mt-1">
-                    <AlertTriangle className="w-3 h-3 text-amber-500" />
-                    <span className="text-xs text-amber-600 dark:text-amber-400">
+                    <AlertTriangle className="w-3 h-3 text-warning" />
+                    <span className="text-xs text-warning">
                       Permissions: {plugin.permissions.join(', ')}
                     </span>
                   </div>
diff --git a/app/globals.css b/app/globals.css
index f8acf899..d0ac0078 100644
--- a/app/globals.css
+++ b/app/globals.css
@@ -23,6 +23,39 @@
   --color-popover: #ffffff;
   --color-popover-foreground: #0f172a;
 
+  /* Sidebar */
+  --color-sidebar: #f8fafc;
+  --color-sidebar-foreground: #0f172a;
+  --color-sidebar-border: #e2e8f0;
+  --color-sidebar-accent: #f1f5f9;
+  --color-sidebar-accent-foreground: #0f172a;
+
+  /* Card */
+  --color-card: #ffffff;
+  --color-card-foreground: #0f172a;
+
+  /* Semantic status colors */
+  --color-success: #22c55e;
+  --color-success-foreground: #ffffff;
+  --color-warning: #eab308;
+  --color-warning-foreground: #ffffff;
+  --color-info: #3b82f6;
+  --color-info-foreground: #ffffff;
+
+  /* Selection states */
+  --color-selection: #dbeafe;
+  --color-selection-foreground: #1e40af;
+
+  /* Unread indicator */
+  --color-unread: #3b82f6;
+
+  /* Chart colors */
+  --color-chart-1: #3b82f6;
+  --color-chart-2: #22c55e;
+  --color-chart-3: #f59e0b;
+  --color-chart-4: #ef4444;
+  --color-chart-5: #8b5cf6;
+
   /* Settings variables */
   --font-size-base: 16px;
   --list-item-height: 48px;
@@ -54,6 +87,39 @@
   --color-destructive-foreground: #fafafa;
   --color-popover: #1c1c1c;
   --color-popover-foreground: #fafafa;
+
+  /* Sidebar */
+  --color-sidebar: #0a0a0a;
+  --color-sidebar-foreground: #fafafa;
+  --color-sidebar-border: #262626;
+  --color-sidebar-accent: #1a1a1a;
+  --color-sidebar-accent-foreground: #fafafa;
+
+  /* Card */
+  --color-card: #141414;
+  --color-card-foreground: #fafafa;
+
+  /* Semantic status colors */
+  --color-success: #16a34a;
+  --color-success-foreground: #ffffff;
+  --color-warning: #ca8a04;
+  --color-warning-foreground: #ffffff;
+  --color-info: #60a5fa;
+  --color-info-foreground: #ffffff;
+
+  /* Selection states */
+  --color-selection: rgba(59, 130, 246, 0.25);
+  --color-selection-foreground: #93c5fd;
+
+  /* Unread indicator */
+  --color-unread: #60a5fa;
+
+  /* Chart colors */
+  --color-chart-1: #60a5fa;
+  --color-chart-2: #4ade80;
+  --color-chart-3: #fbbf24;
+  --color-chart-4: #f87171;
+  --color-chart-5: #a78bfa;
 }
 
 @theme inline {
@@ -74,6 +140,27 @@
   --color-destructive-foreground: var(--color-destructive-foreground);
   --color-popover: var(--color-popover);
   --color-popover-foreground: var(--color-popover-foreground);
+  --color-sidebar: var(--color-sidebar);
+  --color-sidebar-foreground: var(--color-sidebar-foreground);
+  --color-sidebar-border: var(--color-sidebar-border);
+  --color-sidebar-accent: var(--color-sidebar-accent);
+  --color-sidebar-accent-foreground: var(--color-sidebar-accent-foreground);
+  --color-card: var(--color-card);
+  --color-card-foreground: var(--color-card-foreground);
+  --color-success: var(--color-success);
+  --color-success-foreground: var(--color-success-foreground);
+  --color-warning: var(--color-warning);
+  --color-warning-foreground: var(--color-warning-foreground);
+  --color-info: var(--color-info);
+  --color-info-foreground: var(--color-info-foreground);
+  --color-selection: var(--color-selection);
+  --color-selection-foreground: var(--color-selection-foreground);
+  --color-unread: var(--color-unread);
+  --color-chart-1: var(--color-chart-1);
+  --color-chart-2: var(--color-chart-2);
+  --color-chart-3: var(--color-chart-3);
+  --color-chart-4: var(--color-chart-4);
+  --color-chart-5: var(--color-chart-5);
 }
 
 * {
@@ -163,21 +250,16 @@ body {
 }
 
 .email-content blockquote {
-  border-left: 3px solid #d1d5db;
+  border-left: 3px solid var(--color-border);
   padding-left: 1rem;
   margin: 1rem 0;
-  color: #4b5563;
+  color: var(--color-muted-foreground);
   font-style: italic;
 }
 
-.dark .email-content blockquote {
-  border-left-color: #4b5563;
-  color: #9ca3af;
-}
-
 .email-content pre {
-  background-color: #f5f5f7;
-  border: 1px solid #e5e7eb;
+  background-color: var(--color-muted);
+  border: 1px solid var(--color-border);
   border-radius: 0.375rem;
   padding: 1rem;
   font-family: "SF Mono", Monaco, Menlo, Consolas, monospace;
@@ -186,23 +268,13 @@ body {
   margin: 1rem 0;
 }
 
-.dark .email-content pre {
-  background-color: #1f2937;
-  border-color: #374151;
-}
-
 .email-content code {
-  background-color: #f3f4f6;
+  background-color: var(--color-muted);
   padding: 0.125rem 0.375rem;
   border-radius: 0.25rem;
   font-family: "SF Mono", Monaco, Menlo, Consolas, monospace;
   font-size: 0.875rem;
-  color: #dc2626;
-}
-
-.dark .email-content code {
-  background-color: #374151;
-  color: #f87171;
+  color: var(--color-destructive);
 }
 
 .email-content h1,
@@ -282,26 +354,15 @@ body {
 .email-content table[border="1"] th,
 .email-content table[border="1"] td {
   padding: 0.625rem;
-  border: 1px solid #e5e7eb;
+  border: 1px solid var(--color-border);
   text-align: left;
 }
 
 .email-content table.data-table th,
 .email-content table[border="1"] th {
-  background-color: #f9fafb;
+  background-color: var(--color-muted);
   font-weight: 600;
-  color: #374151;
-}
-
-.dark .email-content table.data-table th,
-.dark .email-content table[border="1"] th {
-  background-color: #1f2937;
-  color: #d1d5db;
-}
-
-.dark .email-content table.data-table td,
-.dark .email-content table[border="1"] td {
-  border-color: #374151;
+  color: var(--color-foreground);
 }
 
 /* Reset styles for layout tables (commonly used in HTML emails) */
@@ -323,28 +384,19 @@ body {
 
 .email-content hr {
   border: none;
-  border-top: 1px solid #e5e7eb;
+  border-top: 1px solid var(--color-border);
   margin: 1.5rem 0;
 }
 
-.dark .email-content hr {
-  border-top-color: #374151;
-}
-
 /* Email thread quoted text */
 .email-content .quoted-text {
-  border-left: 3px solid #d1d5db;
+  border-left: 3px solid var(--color-border);
   padding-left: 1rem;
   margin: 1rem 0;
-  color: #4b5563;
+  color: var(--color-muted-foreground);
   opacity: 0.8;
 }
 
-.dark .email-content .quoted-text {
-  border-left-color: #4b5563;
-  color: #9ca3af;
-}
-
 /* Toast animations */
 @keyframes toast-enter {
   from {
diff --git a/components/calendar/calendar-day-view.tsx b/components/calendar/calendar-day-view.tsx
index 87a98321..55feb06d 100644
--- a/components/calendar/calendar-day-view.tsx
+++ b/components/calendar/calendar-day-view.tsx
@@ -182,7 +182,7 @@ export function CalendarDayView({
                         className={cn(
                           "flex-shrink-0 w-3.5 h-3.5 rounded-full border flex items-center justify-center",
                           isCompleted
-                            ? "bg-green-500 border-green-500 text-white"
+                            ? "bg-success border-success text-success-foreground"
                             : "border-muted-foreground/40 hover:border-primary"
                         )}
                       >
@@ -288,8 +288,8 @@ export function CalendarDayView({
                 style={{ top: (nowMinutes / 60) * HOUR_HEIGHT }}
               >
                 <div className="flex items-center">
-                  <div className="w-2.5 h-2.5 rounded-full bg-red-500 -ml-1" />
-                  <div className="flex-1 h-px bg-red-500" />
+                  <div className="w-2.5 h-2.5 rounded-full bg-destructive -ml-1" />
+                  <div className="flex-1 h-px bg-destructive" />
                 </div>
               </div>
             )}
diff --git a/components/calendar/calendar-week-view.tsx b/components/calendar/calendar-week-view.tsx
index 0817e758..cede7e4a 100644
--- a/components/calendar/calendar-week-view.tsx
+++ b/components/calendar/calendar-week-view.tsx
@@ -252,7 +252,7 @@ export function CalendarWeekView({
                         >
                           <span className={cn(
                             "w-2.5 h-2.5 rounded-full border flex-shrink-0 flex items-center justify-center",
-                            isCompleted ? "bg-green-500 border-green-500" : "border-current"
+                            isCompleted ? "bg-success border-success" : "border-current"
                           )}>
                             {isCompleted && <Check className="h-2 w-2 text-white" />}
                           </span>
@@ -402,8 +402,8 @@ export function CalendarWeekView({
                       style={{ top: (nowMinutes / 60) * HOUR_HEIGHT }}
                     >
                       <div className="flex items-center">
-                        <div className="w-2 h-2 rounded-full bg-red-500 -ml-1" />
-                        <div className="flex-1 h-px bg-red-500" />
+                        <div className="w-2 h-2 rounded-full bg-destructive -ml-1" />
+                        <div className="flex-1 h-px bg-destructive" />
                       </div>
                     </div>
                   )}
diff --git a/components/calendar/event-detail-popover.tsx b/components/calendar/event-detail-popover.tsx
index 7db26f89..0611e983 100644
--- a/components/calendar/event-detail-popover.tsx
+++ b/components/calendar/event-detail-popover.tsx
@@ -297,7 +297,7 @@ export function EventDetailPopover({
             <p className="text-xs text-muted-foreground mt-0.5 pl-[18px]">
               {calendar.name}
               {event.status === "tentative" && (
-                <span className="ml-2 inline-flex items-center px-1.5 py-0.5 rounded text-[10px] font-medium bg-amber-100 text-amber-800 dark:bg-amber-900/30 dark:text-amber-400">
+                <span className="ml-2 inline-flex items-center px-1.5 py-0.5 rounded text-[10px] font-medium bg-warning/15 text-warning">
                   {t("detail.tentative")}
                 </span>
               )}
@@ -507,8 +507,8 @@ export function EventDetailPopover({
               onClick={() => onRsvp("accepted")}
               className={
                 userCurrentStatus === "accepted"
-                  ? "bg-green-600 hover:bg-green-700 text-white dark:bg-green-500 dark:hover:bg-green-600"
-                  : "text-green-600 dark:text-green-400 border-green-300 dark:border-green-700 hover:bg-green-50 dark:hover:bg-green-950"
+                  ? "bg-success hover:bg-success/80 text-success-foreground"
+                  : "text-success border-success/30 hover:bg-success/10"
               }
             >
               {userCurrentStatus === "accepted" && <Check className="w-3.5 h-3.5 mr-1" />}
@@ -520,8 +520,8 @@ export function EventDetailPopover({
               onClick={() => onRsvp("tentative")}
               className={
                 userCurrentStatus === "tentative"
-                  ? "bg-amber-600 hover:bg-amber-700 text-white dark:bg-amber-500 dark:hover:bg-amber-600"
-                  : "border border-amber-500 text-amber-600 hover:bg-amber-50 dark:text-amber-400 dark:hover:bg-amber-950"
+                  ? "bg-warning hover:bg-warning/80 text-warning-foreground"
+                  : "border border-warning/30 text-warning hover:bg-warning/10"
               }
             >
               {userCurrentStatus === "tentative" && <Check className="w-3.5 h-3.5 mr-1" />}
@@ -533,8 +533,8 @@ export function EventDetailPopover({
               onClick={() => onRsvp("declined")}
               className={
                 userCurrentStatus === "declined"
-                  ? "bg-red-600 hover:bg-red-700 text-white dark:bg-red-500 dark:hover:bg-red-600"
-                  : "text-red-600 hover:bg-red-50 dark:text-red-400 dark:hover:bg-red-950"
+                  ? "bg-destructive hover:bg-destructive/80 text-destructive-foreground"
+                  : "text-destructive hover:bg-destructive/10"
               }
             >
               {userCurrentStatus === "declined" && <Check className="w-3.5 h-3.5 mr-1" />}
@@ -548,7 +548,7 @@ export function EventDetailPopover({
       <div className="px-4 py-2.5 border-t border-border flex items-center gap-1.5">
         {showDeleteConfirm ? (
           <div className="flex items-center gap-2 w-full">
-            <span className="text-sm text-red-600 dark:text-red-400 flex-1">
+            <span className="text-sm text-destructive flex-1">
               {t("form.delete_confirm")}
             </span>
             <Button
@@ -611,9 +611,9 @@ function ParticipantStatusBadge({
   t: ReturnType<typeof useTranslations>;
 }) {
   const colors: Record<string, string> = {
-    accepted: "text-green-600 dark:text-green-400",
-    declined: "text-red-600 dark:text-red-400",
-    tentative: "text-amber-600 dark:text-amber-400",
+    accepted: "text-success",
+    declined: "text-destructive",
+    tentative: "text-warning",
     "needs-action": "text-muted-foreground",
   };
   const labels: Record<string, string> = {
diff --git a/components/calendar/event-modal.tsx b/components/calendar/event-modal.tsx
index 5af93c9d..a45e359e 100644
--- a/components/calendar/event-modal.tsx
+++ b/components/calendar/event-modal.tsx
@@ -530,8 +530,8 @@ export function EventModal({
                   variant={userCurrentStatus === "accepted" ? "default" : "outline"}
                   onClick={() => handleRsvp("accepted")}
                   className={userCurrentStatus === "accepted"
-                    ? "bg-green-600 hover:bg-green-700 text-white dark:bg-green-500 dark:hover:bg-green-600"
-                    : "text-green-600 dark:text-green-400 border-green-300 dark:border-green-700 hover:bg-green-50 dark:hover:bg-green-950"}
+                    ? "bg-success hover:bg-success/80 text-success-foreground"
+                    : "text-success border-success/30 hover:bg-success/10"}
                 >
                   {userCurrentStatus === "accepted" && <Check className="w-4 h-4 mr-1" />}
                   {t("participants.accepted")}
@@ -541,8 +541,8 @@ export function EventModal({
                   variant={userCurrentStatus === "tentative" ? "default" : "outline"}
                   onClick={() => handleRsvp("tentative")}
                   className={userCurrentStatus === "tentative"
-                    ? "bg-amber-600 hover:bg-amber-700 text-white dark:bg-amber-500 dark:hover:bg-amber-600"
-                    : "border border-amber-500 text-amber-600 hover:bg-amber-50 dark:text-amber-400 dark:hover:bg-amber-950"}
+                    ? "bg-warning hover:bg-warning/80 text-warning-foreground"
+                    : "border border-warning/30 text-warning hover:bg-warning/10"}
                 >
                   {userCurrentStatus === "tentative" && <Check className="w-4 h-4 mr-1" />}
                   {t("participants.tentative")}
@@ -552,8 +552,8 @@ export function EventModal({
                   variant={userCurrentStatus === "declined" ? "default" : "ghost"}
                   onClick={() => handleRsvp("declined")}
                   className={userCurrentStatus === "declined"
-                    ? "bg-red-600 hover:bg-red-700 text-white dark:bg-red-500 dark:hover:bg-red-600"
-                    : "text-red-600 hover:bg-red-50 dark:text-red-400 dark:hover:bg-red-950"}
+                    ? "bg-destructive hover:bg-destructive/80 text-destructive-foreground"
+                    : "text-destructive hover:bg-destructive/10"}
                 >
                   {userCurrentStatus === "declined" && <Check className="w-4 h-4 mr-1" />}
                   {t("participants.declined")}
@@ -701,8 +701,8 @@ export function EventModal({
             {onDelete && (
               showDeleteConfirm ? (
                 <div className="flex items-center gap-2">
-                  <span className="text-sm text-red-600 dark:text-red-400">{t("form.delete_confirm")}</span>
-                  <Button variant="outline" size="sm" onClick={() => { onDelete(event.id, hasParticipants || undefined); onClose(); }} className="text-red-600 dark:text-red-400 border-red-300 dark:border-red-700">
+                  <span className="text-sm text-destructive">{t("form.delete_confirm")}</span>
+                  <Button variant="outline" size="sm" onClick={() => { onDelete(event.id, hasParticipants || undefined); onClose(); }} className="text-destructive border-destructive/30">
                     {t("events.delete")}
                   </Button>
                   <Button variant="ghost" size="sm" onClick={() => setShowDeleteConfirm(false)}>
@@ -710,7 +710,7 @@ export function EventModal({
                   </Button>
                 </div>
               ) : (
-                <Button variant="ghost" size="sm" onClick={() => setShowDeleteConfirm(true)} className="text-red-600 dark:text-red-400">
+                <Button variant="ghost" size="sm" onClick={() => setShowDeleteConfirm(true)} className="text-destructive">
                   <Trash2 className="w-4 h-4 mr-1" />
                   {t("events.delete")}
                 </Button>
@@ -997,9 +997,9 @@ function StatusBadge({ status, isOrganizer, t }: {
     return <span className="text-xs text-primary">{t("participants.organizer")}</span>;
   }
   const colors: Record<string, string> = {
-    accepted: "text-green-600 dark:text-green-400",
-    declined: "text-red-600 dark:text-red-400",
-    tentative: "text-amber-600 dark:text-amber-400",
+    accepted: "text-success",
+    declined: "text-destructive",
+    tentative: "text-warning",
     "needs-action": "text-muted-foreground",
   };
   const labels: Record<string, string> = {
diff --git a/components/calendar/ical-import-modal.tsx b/components/calendar/ical-import-modal.tsx
index 2e9657d4..ddf6d5ea 100644
--- a/components/calendar/ical-import-modal.tsx
+++ b/components/calendar/ical-import-modal.tsx
@@ -349,7 +349,7 @@ export function ICalImportModal({ calendars, client, onClose }: ICalImportModalP
           )}
 
           {error && (
-            <div className="text-sm text-red-600 dark:text-red-400 bg-red-50 dark:bg-red-950/30 rounded-md px-3 py-2">
+            <div className="text-sm text-destructive bg-destructive/10 rounded-md px-3 py-2">
               {error}
             </div>
           )}
diff --git a/components/calendar/task-list-view.tsx b/components/calendar/task-list-view.tsx
index c1a79e00..9b9fbd08 100644
--- a/components/calendar/task-list-view.tsx
+++ b/components/calendar/task-list-view.tsx
@@ -204,7 +204,7 @@ export function TaskListView({
                 className={cn(
                   "mt-0.5 flex-shrink-0 w-5 h-5 rounded-full border-2 flex items-center justify-center transition-colors",
                   isCompleted
-                    ? "bg-green-500 border-green-500 text-white"
+                    ? "bg-success border-success text-success-foreground"
                     : "border-muted-foreground/40 hover:border-primary"
                 )}
                 aria-label={isCompleted ? t("tasks.mark_incomplete") : t("tasks.mark_complete")}
diff --git a/components/contacts/__tests__/contact-list-item.test.tsx b/components/contacts/__tests__/contact-list-item.test.tsx
index 252e9888..d4556026 100644
--- a/components/contacts/__tests__/contact-list-item.test.tsx
+++ b/components/contacts/__tests__/contact-list-item.test.tsx
@@ -52,7 +52,7 @@ describe('ContactListItem', () => {
   it('applies selected styling', () => {
     const { container } = render(<ContactListItem contact={contact} {...baseProps} isSelected={true} />);
     const div = container.firstElementChild;
-    expect(div?.className).toContain('bg-blue-200');
+    expect(div?.className).toContain('bg-selection');
   });
 
   it('shows email as display name when no name exists', () => {
diff --git a/components/contacts/contact-import-dialog.tsx b/components/contacts/contact-import-dialog.tsx
index 372e1b49..c399b0fc 100644
--- a/components/contacts/contact-import-dialog.tsx
+++ b/components/contacts/contact-import-dialog.tsx
@@ -205,7 +205,7 @@ export function ContactImportDialog({
                       )}
                     </div>
                     {isDupe && (
-                      <span className="text-xs px-1.5 py-0.5 rounded bg-amber-100 dark:bg-amber-900 text-amber-700 dark:text-amber-400 flex-shrink-0">
+                      <span className="text-xs px-1.5 py-0.5 rounded bg-warning/15 text-warning flex-shrink-0">
                         {t("import.duplicate")}
                       </span>
                     )}
diff --git a/components/contacts/contact-list-item.tsx b/components/contacts/contact-list-item.tsx
index 2b78a634..0f330e65 100644
--- a/components/contacts/contact-list-item.tsx
+++ b/components/contacts/contact-list-item.tsx
@@ -59,9 +59,9 @@ export function ContactListItem({ contact, isSelected, isChecked, hasSelection,
       className={cn(
         "w-full flex items-center cursor-pointer select-none transition-all duration-200 border-b border-border",
         isSelected
-          ? "bg-blue-200 dark:bg-blue-900/50 shadow-sm"
+          ? "bg-selection shadow-sm"
           : "bg-background hover:bg-muted hover:shadow-sm",
-        isChecked && !isSelected && "ring-2 ring-primary/20 bg-blue-100 dark:bg-blue-900/30",
+        isChecked && !isSelected && "ring-2 ring-primary/20 bg-selection/60",
       )}
       style={{ gap: 'var(--density-item-gap)', paddingInline: '16px', paddingBlock: 'var(--density-item-py)' }}
     >
diff --git a/components/email/calendar-invitation-banner.tsx b/components/email/calendar-invitation-banner.tsx
index 43ac924d..dd398658 100644
--- a/components/email/calendar-invitation-banner.tsx
+++ b/components/email/calendar-invitation-banner.tsx
@@ -171,11 +171,11 @@ function getParticipationLabel(
 function getParticipationTone(status: string | null): string {
   switch (status) {
     case 'accepted':
-      return 'bg-green-100 text-green-700 dark:bg-green-900/30 dark:text-green-400';
+      return 'bg-success/15 text-success';
     case 'tentative':
-      return 'bg-amber-100 text-amber-700 dark:bg-amber-900/30 dark:text-amber-400';
+      return 'bg-warning/15 text-warning';
     case 'declined':
-      return 'bg-red-100 text-red-700 dark:bg-red-900/30 dark:text-red-400';
+      return 'bg-destructive/15 text-destructive';
     default:
       return 'bg-muted text-muted-foreground';
   }
@@ -731,9 +731,9 @@ export function CalendarInvitationBanner({ email }: CalendarInvitationBannerProp
 
   if (state === 'error') {
     return (
-      <div className="rounded-lg border border-red-200 dark:border-red-900/50 bg-red-50/50 dark:bg-red-950/20 px-4 py-3 flex items-center gap-2.5">
-        <AlertCircle className="w-4 h-4 text-red-600 dark:text-red-400 flex-shrink-0" />
-        <span className="text-sm text-red-600 dark:text-red-400">{t('parse_error')}</span>
+      <div className="rounded-lg border border-destructive/20 bg-destructive/10 px-4 py-3 flex items-center gap-2.5">
+        <AlertCircle className="w-4 h-4 text-destructive flex-shrink-0" />
+        <span className="text-sm text-destructive">{t('parse_error')}</span>
       </div>
     );
   }
@@ -744,7 +744,7 @@ export function CalendarInvitationBanner({ email }: CalendarInvitationBannerProp
       <div className="flex items-center justify-between px-4 py-2.5 bg-muted/30 border-b border-border">
         <div className="flex items-center gap-2 min-w-0">
           {isCancellation ? (
-            <CalendarX className="w-4 h-4 text-red-600 dark:text-red-400 flex-shrink-0" />
+            <CalendarX className="w-4 h-4 text-destructive flex-shrink-0" />
           ) : (
             <Calendar className="w-4 h-4 text-primary flex-shrink-0" />
           )}
@@ -808,19 +808,19 @@ export function CalendarInvitationBanner({ email }: CalendarInvitationBannerProp
               <span className={cn(
                 "rounded-full px-2 py-0.5 text-[11px] font-medium",
                 parsedEvent.status === 'cancelled'
-                  ? "bg-red-100 text-red-700 dark:bg-red-900/30 dark:text-red-400"
-                  : "bg-amber-100 text-amber-700 dark:bg-amber-900/30 dark:text-amber-400"
+                  ? "bg-destructive/15 text-destructive"
+                  : "bg-warning/15 text-warning"
               )}>
                 {t(`event_status_${parsedEvent.status}`)}
               </span>
             )}
             {existingEvent && (
-              <span className="rounded-full bg-green-100 px-2 py-0.5 text-[11px] font-medium text-green-700 dark:bg-green-900/30 dark:text-green-400">
+              <span className="rounded-full bg-success/15 px-2 py-0.5 text-[11px] font-medium text-success">
                 {t('already_in_calendar')}
               </span>
             )}
             {userIsOrganizer && (
-              <span className="rounded-full bg-blue-100 px-2 py-0.5 text-[11px] font-medium text-blue-700 dark:bg-blue-900/30 dark:text-blue-400">
+              <span className="rounded-full bg-info/15 px-2 py-0.5 text-[11px] font-medium text-info">
                 {t('organizer_role')}
               </span>
             )}
@@ -833,7 +833,7 @@ export function CalendarInvitationBanner({ email }: CalendarInvitationBannerProp
               </span>
             )}
             {actionFeedback && (
-              <span className="rounded-full bg-green-100 px-2 py-0.5 text-[11px] font-medium text-green-700 dark:bg-green-900/30 dark:text-green-400">
+              <span className="rounded-full bg-success/15 px-2 py-0.5 text-[11px] font-medium text-success">
                 {actionFeedback}
               </span>
             )}
@@ -877,8 +877,8 @@ export function CalendarInvitationBanner({ email }: CalendarInvitationBannerProp
           <div className={cn(
             'flex items-start gap-1.5 text-xs rounded-md px-3 py-2',
             trustAssessment.level === 'warning'
-              ? 'bg-red-50 dark:bg-red-950/20 text-red-700 dark:text-red-400 border border-red-200 dark:border-red-900/50'
-              : 'bg-amber-50 dark:bg-amber-950/20 text-amber-700 dark:text-amber-400 border border-amber-200 dark:border-amber-900/50'
+              ? 'bg-destructive/10 text-destructive border border-destructive/20'
+              : 'bg-warning/10 text-warning border border-warning/20'
           )}>
             <AlertCircle className="w-3.5 h-3.5 mt-0.5 flex-shrink-0" />
             <span>{trustMessage}</span>
@@ -887,7 +887,7 @@ export function CalendarInvitationBanner({ email }: CalendarInvitationBannerProp
 
         {/* Action error */}
         {actionError && (
-          <div className="flex items-start gap-1.5 text-xs text-red-600 dark:text-red-400 rounded-md px-3 py-2 bg-red-50 dark:bg-red-950/20 border border-red-200 dark:border-red-900/50">
+          <div className="flex items-start gap-1.5 text-xs text-destructive rounded-md px-3 py-2 bg-destructive/10 border border-destructive/20">
             <AlertCircle className="w-3.5 h-3.5 mt-0.5 flex-shrink-0" />
             <span>{actionError}</span>
           </div>
@@ -905,8 +905,8 @@ export function CalendarInvitationBanner({ email }: CalendarInvitationBannerProp
               className={cn(
                 "inline-flex items-center gap-1.5 text-sm font-medium px-3 py-1.5 rounded-md transition-colors min-h-[36px] disabled:opacity-50 border",
                 currentRsvp === 'accepted'
-                  ? "bg-green-100 dark:bg-green-900/30 text-green-700 dark:text-green-400 border-green-200 dark:border-green-800"
-                  : "text-muted-foreground hover:text-green-700 dark:hover:text-green-400 border-border hover:border-green-300 dark:hover:border-green-800 hover:bg-green-50 dark:hover:bg-green-950/20"
+                  ? "bg-success/15 text-success border-success/20"
+                  : "text-muted-foreground hover:text-success border-border hover:border-success/30 hover:bg-success/10"
               )}
             >
               <Check className="w-3.5 h-3.5" />
@@ -919,8 +919,8 @@ export function CalendarInvitationBanner({ email }: CalendarInvitationBannerProp
               className={cn(
                 "inline-flex items-center gap-1.5 text-sm font-medium px-3 py-1.5 rounded-md transition-colors min-h-[36px] disabled:opacity-50 border",
                 currentRsvp === 'tentative'
-                  ? "bg-amber-100 dark:bg-amber-900/30 text-amber-700 dark:text-amber-400 border-amber-200 dark:border-amber-800"
-                  : "text-muted-foreground hover:text-amber-700 dark:hover:text-amber-400 border-border hover:border-amber-300 dark:hover:border-amber-800 hover:bg-amber-50 dark:hover:bg-amber-950/20"
+                  ? "bg-warning/15 text-warning border-warning/20"
+                  : "text-muted-foreground hover:text-warning border-border hover:border-warning/30 hover:bg-warning/10"
               )}
             >
               <HelpCircle className="w-3.5 h-3.5" />
@@ -933,8 +933,8 @@ export function CalendarInvitationBanner({ email }: CalendarInvitationBannerProp
               className={cn(
                 "inline-flex items-center gap-1.5 text-sm font-medium px-3 py-1.5 rounded-md transition-colors min-h-[36px] disabled:opacity-50 border",
                 currentRsvp === 'declined'
-                  ? "bg-red-100 dark:bg-red-900/30 text-red-700 dark:text-red-400 border-red-200 dark:border-red-800"
-                  : "text-muted-foreground hover:text-red-700 dark:hover:text-red-400 border-border hover:border-red-300 dark:hover:border-red-800 hover:bg-red-50 dark:hover:bg-red-950/20"
+                  ? "bg-destructive/15 text-destructive border-destructive/20"
+                  : "text-muted-foreground hover:text-destructive border-border hover:border-destructive/30 hover:bg-destructive/10"
               )}
             >
               <X className="w-3.5 h-3.5" />
diff --git a/components/email/email-list-item.tsx b/components/email/email-list-item.tsx
index 0ddded47..4858ef25 100644
--- a/components/email/email-list-item.tsx
+++ b/components/email/email-list-item.tsx
@@ -87,15 +87,15 @@ export function EmailListItem({ email, selected, onClick, onContextMenu, onToggl
         // Apply color tag as background, with selected and unread states
         colorTag ? colorTag : (
           selected
-            ? "bg-blue-200 dark:bg-blue-900/50"
+            ? "bg-selection"
             : "bg-background"
         ),
         selected && !colorTag && "shadow-sm",
         !colorTag && !selected && "hover:bg-muted hover:shadow-sm",
         colorTag && "hover:brightness-95 dark:hover:brightness-110",
-        isUnread && !selected && !colorTag && "bg-amber-50 dark:bg-amber-900/20",
+        isUnread && !selected && !colorTag && "bg-warning/10",
         // Add visual feedback for checked state
-        isChecked && "ring-2 ring-primary/20 bg-blue-100 dark:bg-blue-900/30",
+        isChecked && "ring-2 ring-primary/20 bg-selection/60",
         // Drag state visual feedback
         isDragging && "opacity-50 scale-[0.98] ring-2 ring-primary/30",
         // Long press visual feedback
@@ -140,7 +140,7 @@ export function EmailListItem({ email, selected, onClick, onContextMenu, onToggl
         {/* Unread indicator */}
         {isUnread && (
           <div className="absolute left-1 top-1/2 -translate-y-1/2">
-            <Circle className="w-2 h-2 fill-blue-600 text-blue-600 dark:fill-blue-400 dark:text-blue-400" />
+            <Circle className="w-2 h-2 fill-unread text-unread" />
           </div>
         )}
 
@@ -172,7 +172,7 @@ export function EmailListItem({ email, selected, onClick, onContextMenu, onToggl
                   <Star className="w-3.5 h-3.5 fill-amber-400 text-amber-400" />
                 )}
                 {isImportant && (
-                  <span className="px-1.5 py-0.5 text-xs bg-amber-100 dark:bg-amber-900/30 text-amber-700 dark:text-amber-400 rounded font-medium">
+                  <span className="px-1.5 py-0.5 text-xs bg-warning/15 text-warning dark:text-warning rounded font-medium">
                     Important
                   </span>
                 )}
diff --git a/components/email/email-viewer.tsx b/components/email/email-viewer.tsx
index 4a14d1a0..0beae7dc 100644
--- a/components/email/email-viewer.tsx
+++ b/components/email/email-viewer.tsx
@@ -3541,7 +3541,7 @@ export function EmailViewer({
                   ) : null;
                 })()}
                 {isImportant && (
-                  <span className="px-1.5 lg:px-2 py-0.5 bg-amber-50 dark:bg-amber-900/30 text-amber-700 dark:text-amber-400 rounded-full text-xs font-medium whitespace-nowrap flex-shrink-0 self-center">
+                  <span className="px-1.5 lg:px-2 py-0.5 bg-warning/15 text-warning rounded-full text-xs font-medium whitespace-nowrap flex-shrink-0 self-center">
                     {t('important')}
                   </span>
                 )}
@@ -4372,9 +4372,9 @@ export function EmailViewer({
 
         {/* Draft Banner */}
         {isDraft && (
-          <div className="border-b border-border bg-amber-50 dark:bg-amber-950/30">
+          <div className="border-b border-border bg-warning/10">
             <div className="max-w-4xl mx-auto px-6 py-2.5 flex items-center justify-between">
-              <div className="flex items-center gap-2 text-amber-700 dark:text-amber-400">
+              <div className="flex items-center gap-2 text-warning">
                 <File className="w-4 h-4" />
                 <span className="text-sm font-medium">{t('draft_banner')}</span>
               </div>
diff --git a/components/email/smime-status-banner.tsx b/components/email/smime-status-banner.tsx
index d8ca2210..010c45f4 100644
--- a/components/email/smime-status-banner.tsx
+++ b/components/email/smime-status-banner.tsx
@@ -83,10 +83,10 @@ export function SmimeStatusBanner({ status, onUnlockKey, className }: SmimeStatu
   if (items.length === 0) return null;
 
   const variantStyles = {
-    success: 'bg-green-50 dark:bg-green-950/30 text-green-700 dark:text-green-400 border-green-200 dark:border-green-800',
-    warning: 'bg-yellow-50 dark:bg-yellow-950/30 text-yellow-700 dark:text-yellow-400 border-yellow-200 dark:border-yellow-800',
-    error: 'bg-red-50 dark:bg-red-950/30 text-red-700 dark:text-red-400 border-red-200 dark:border-red-800',
-    info: 'bg-blue-50 dark:bg-blue-950/30 text-blue-700 dark:text-blue-400 border-blue-200 dark:border-blue-800',
+    success: 'bg-success/10 text-success border-success/30',
+    warning: 'bg-warning/10 text-warning border-warning/30',
+    error: 'bg-destructive/10 text-destructive border-destructive/30',
+    info: 'bg-info/10 text-info border-info/30',
   };
 
   return (
diff --git a/components/email/thread-email-item.tsx b/components/email/thread-email-item.tsx
index 4c927028..05933a3d 100644
--- a/components/email/thread-email-item.tsx
+++ b/components/email/thread-email-item.tsx
@@ -85,9 +85,9 @@ export function ThreadEmailItem({
         "pl-12 pr-4",
         "border-l-2 border-l-transparent",
         selected
-          ? "bg-blue-200 dark:bg-blue-900/50 border-l-primary"
+          ? "bg-selection border-l-primary"
           : "hover:bg-muted/50",
-        isUnread && !selected && "bg-amber-50 dark:bg-amber-900/20",
+        isUnread && !selected && "bg-warning/10",
         !isLast && "border-b border-border/30",
         isChecked && "ring-2 ring-primary/20 bg-accent/40",
         isDragging && "opacity-50 scale-[0.98] ring-2 ring-primary/30",
@@ -121,7 +121,7 @@ export function ThreadEmailItem({
         {/* Unread indicator */}
         {isUnread && (
           <div className="absolute left-7 top-1/2 -translate-y-1/2">
-            <Circle className="w-1.5 h-1.5 fill-blue-600 text-blue-600 dark:fill-blue-400 dark:text-blue-400" />
+            <Circle className="w-1.5 h-1.5 fill-unread text-unread" />
           </div>
         )}
 
diff --git a/components/email/thread-list-item.tsx b/components/email/thread-list-item.tsx
index b2e5d13b..87a3b332 100644
--- a/components/email/thread-list-item.tsx
+++ b/components/email/thread-list-item.tsx
@@ -156,7 +156,7 @@ const SingleEmailItem = React.forwardRef<HTMLDivElement, SingleEmailItemProps>(
 
           {isUnread && (
             <div className="absolute left-1 top-1/2 -translate-y-1/2">
-              <Circle className="w-2 h-2 fill-blue-600 text-blue-600 dark:fill-blue-400 dark:text-blue-400" />
+              <Circle className="w-2 h-2 fill-unread text-unread" />
             </div>
           )}
 
@@ -456,7 +456,7 @@ export const ThreadListItem = React.forwardRef<HTMLDivElement, ThreadListItemPro
 
             {hasUnread && (
               <div className="absolute left-1 top-1/2 -translate-y-1/2">
-                <Circle className="w-2 h-2 fill-blue-600 text-blue-600 dark:fill-blue-400 dark:text-blue-400" />
+                <Circle className="w-2 h-2 fill-unread text-unread" />
               </div>
             )}
 
diff --git a/components/error/error-fallbacks.tsx b/components/error/error-fallbacks.tsx
index 045fb9b7..1c1dc5ba 100644
--- a/components/error/error-fallbacks.tsx
+++ b/components/error/error-fallbacks.tsx
@@ -94,7 +94,7 @@ export function EmailViewerErrorFallback({ resetError, t }: FallbackProps) {
 export function ComposerErrorFallback({ resetError, t }: FallbackProps) {
   return (
     <div className="flex flex-col h-full bg-background border rounded-lg items-center justify-center p-8">
-      <AlertCircle className="w-10 h-10 text-amber-500 mb-3" />
+      <AlertCircle className="w-10 h-10 text-warning mb-3" />
       <p className="text-sm text-muted-foreground text-center mb-4">
         {t("composer_error")}
       </p>
diff --git a/components/filters/filter-rule-modal.tsx b/components/filters/filter-rule-modal.tsx
index 081f536b..9bd5ed36 100644
--- a/components/filters/filter-rule-modal.tsx
+++ b/components/filters/filter-rule-modal.tsx
@@ -299,7 +299,7 @@ export function FilterRuleModal({
                     type="button"
                     onClick={() => removeCondition(index)}
                     disabled={conditions.length <= 1}
-                    className="p-1.5 rounded hover:bg-muted text-muted-foreground hover:text-red-600 dark:hover:text-red-400 transition-colors disabled:opacity-30 disabled:pointer-events-none"
+                    className="p-1.5 rounded hover:bg-muted text-muted-foreground hover:text-destructive transition-colors disabled:opacity-30 disabled:pointer-events-none"
                     aria-label={t("delete_rule")}
                   >
                     <Trash2 className="w-4 h-4" />
@@ -387,7 +387,7 @@ export function FilterRuleModal({
                     type="button"
                     onClick={() => removeAction(index)}
                     disabled={actions.length <= 1}
-                    className="p-1.5 rounded hover:bg-muted text-muted-foreground hover:text-red-600 dark:hover:text-red-400 transition-colors disabled:opacity-30 disabled:pointer-events-none"
+                    className="p-1.5 rounded hover:bg-muted text-muted-foreground hover:text-destructive transition-colors disabled:opacity-30 disabled:pointer-events-none"
                     aria-label={t("delete_rule")}
                   >
                     <Trash2 className="w-4 h-4" />
diff --git a/components/filters/sieve-editor-modal.tsx b/components/filters/sieve-editor-modal.tsx
index 19655814..12652844 100644
--- a/components/filters/sieve-editor-modal.tsx
+++ b/components/filters/sieve-editor-modal.tsx
@@ -93,7 +93,7 @@ export function SieveEditorModal({
         </div>
 
         <div className="px-6 py-4 flex-1 overflow-hidden flex flex-col space-y-4">
-          <div className="flex items-start gap-2 p-3 rounded-md bg-amber-50 dark:bg-amber-900/20 border border-amber-200 dark:border-amber-800 text-sm text-amber-700 dark:text-amber-400">
+          <div className="flex items-start gap-2 p-3 rounded-md bg-warning/10 border border-warning/20 text-sm text-warning">
             <AlertTriangle className="w-4 h-4 mt-0.5 flex-shrink-0" />
             <p>{t("warning")}</p>
           </div>
@@ -131,8 +131,8 @@ export function SieveEditorModal({
             <div
               className={`flex items-start gap-2 p-3 rounded-md text-sm ${
                 validationResult.isValid
-                  ? "bg-green-50 dark:bg-green-900/20 border border-green-200 dark:border-green-800 text-green-700 dark:text-green-400"
-                  : "bg-red-50 dark:bg-red-900/20 border border-red-200 dark:border-red-800 text-red-700 dark:text-red-400"
+                  ? "bg-success/10 border border-success/20 text-success"
+                  : "bg-destructive/10 border border-destructive/20 text-destructive"
               }`}
             >
               {validationResult.isValid ? (
@@ -157,7 +157,7 @@ export function SieveEditorModal({
           )}
 
           {showSaveWarning && (
-            <div className="flex items-start gap-2 p-3 rounded-md bg-amber-50 dark:bg-amber-900/20 border border-amber-200 dark:border-amber-800 text-sm text-amber-700 dark:text-amber-400">
+            <div className="flex items-start gap-2 p-3 rounded-md bg-warning/10 border border-warning/20 text-sm text-warning">
               <AlertTriangle className="w-4 h-4 mt-0.5 flex-shrink-0" />
               <p>{t("save_warning")}</p>
             </div>
diff --git a/components/layout/navigation-rail.tsx b/components/layout/navigation-rail.tsx
index 4b421cfd..9251a20b 100644
--- a/components/layout/navigation-rail.tsx
+++ b/components/layout/navigation-rail.tsx
@@ -73,10 +73,10 @@ function StorageQuotaCircle({ quota, usagePercent }: { quota: { used: number; to
 
   const free = quota.total - quota.used;
   const strokeColor = usagePercent > 90
-    ? "stroke-red-500 dark:stroke-red-400"
+    ? "stroke-destructive"
     : usagePercent > 70
-      ? "stroke-amber-500 dark:stroke-amber-400"
-      : "stroke-green-500 dark:stroke-green-400";
+      ? "stroke-warning"
+      : "stroke-success";
 
   return (
     <div className="relative">
@@ -123,10 +123,10 @@ function StorageQuotaCircle({ quota, usagePercent }: { quota: { used: number; to
               className={cn(
                 "h-1.5 rounded-full transition-all",
                 usagePercent > 90
-                  ? "bg-red-500 dark:bg-red-400"
+                  ? "bg-destructive"
                   : usagePercent > 70
-                    ? "bg-amber-500 dark:bg-amber-400"
-                    : "bg-green-500 dark:bg-green-400"
+                    ? "bg-warning"
+                    : "bg-success"
               )}
               style={{ width: `${usagePercent}%` }}
             />
diff --git a/components/settings/plugins-settings.tsx b/components/settings/plugins-settings.tsx
index ec9541ea..86c19afc 100644
--- a/components/settings/plugins-settings.tsx
+++ b/components/settings/plugins-settings.tsx
@@ -68,7 +68,7 @@ export function PluginsSettings() {
   };
 
   return (
-    <SettingsSection title="Plugins" description="Manage installed plugins. Upload plugin .zip files to add new functionality.">
+    <SettingsSection title="Plugins" description="Manage installed plugins. Upload plugin .zip files to add new functionality." experimental experimentalDescription="Plugins is an experimental feature. The plugin API is not yet stable and may change between releases, which could break existing plugins. Plugins run in a sandboxed environment but have access to your data within the application. Only install plugins from sources you trust.">
       {/* Plugin List */}
       {plugins.length === 0 ? (
         <div className="flex flex-col items-center justify-center py-12 text-center">
diff --git a/components/settings/settings-section.tsx b/components/settings/settings-section.tsx
index 63b456b4..c55a3f0a 100644
--- a/components/settings/settings-section.tsx
+++ b/components/settings/settings-section.tsx
@@ -1,16 +1,29 @@
 import { ReactNode } from 'react';
-import { Lock } from 'lucide-react';
+import { Lock, FlaskConical } from 'lucide-react';
 import { cn } from '@/lib/utils';
 
 interface SettingsSectionProps {
   title: string;
   description?: string;
   children: ReactNode;
+  experimental?: boolean;
+  experimentalDescription?: string;
 }
 
-export function SettingsSection({ title, description, children }: SettingsSectionProps) {
+export function SettingsSection({ title, description, children, experimental, experimentalDescription }: SettingsSectionProps) {
   return (
     <div className="space-y-4">
+      {experimental && (
+        <div className="flex gap-3 rounded-lg border border-amber-300 bg-amber-50 p-3 dark:border-amber-700 dark:bg-amber-950/30">
+          <FlaskConical className="w-5 h-5 text-amber-600 dark:text-amber-400 mt-0.5 shrink-0" />
+          <div>
+            <p className="text-sm font-medium text-amber-800 dark:text-amber-300">Experimental Feature</p>
+            {experimentalDescription && (
+              <p className="text-xs text-amber-700 dark:text-amber-400/80 mt-1">{experimentalDescription}</p>
+            )}
+          </div>
+        </div>
+      )}
       <div>
         <h3 className="text-lg font-medium text-foreground">{title}</h3>
         {description && (
diff --git a/components/settings/themes-settings.tsx b/components/settings/themes-settings.tsx
index ebd9e733..e97b95c7 100644
--- a/components/settings/themes-settings.tsx
+++ b/components/settings/themes-settings.tsx
@@ -69,7 +69,8 @@ export function ThemesSettings() {
   };
 
   return (
-    <SettingsSection title="Themes" description="Customize the appearance with color themes. Upload .zip theme files or activate built-in presets.">
+    <SettingsSection title="Themes" description="Customize the appearance with color themes. Upload .zip theme files or activate built-in presets." experimental experimentalDescription="Themes is an experimental feature. Custom themes may not cover all UI elements, and theme formats could change in future updates. Built-in presets are stable, but uploaded themes may require updates after application upgrades.">
+
       {/* Theme Grid */}
       <div className="grid grid-cols-2 sm:grid-cols-3 gap-3">
         {/* Default theme card */}
diff --git a/components/settings/vacation-settings.tsx b/components/settings/vacation-settings.tsx
index 1da917e0..15feb26b 100644
--- a/components/settings/vacation-settings.tsx
+++ b/components/settings/vacation-settings.tsx
@@ -240,7 +240,7 @@ export function VacationSettings() {
       {validationWarnings.length > 0 && (
         <div className="space-y-2">
           {validationWarnings.map((warning, i) => (
-            <div key={i} className="flex items-start gap-2 text-sm text-amber-700 dark:text-amber-400">
+            <div key={i} className="flex items-start gap-2 text-sm text-warning">
               <AlertTriangle className="w-4 h-4 mt-0.5 flex-shrink-0" />
               <span>{warning}</span>
             </div>
diff --git a/components/ui/toast.tsx b/components/ui/toast.tsx
index 85ed88c6..c7d940be 100644
--- a/components/ui/toast.tsx
+++ b/components/ui/toast.tsx
@@ -36,17 +36,17 @@ const icons = {
 };
 
 const iconContainerStyles = {
-  success: "bg-emerald-500 text-white",
-  error: "bg-red-500 text-white",
-  info: "bg-blue-500 text-white",
-  warning: "bg-amber-500 text-white",
+  success: "bg-success text-success-foreground",
+  error: "bg-destructive text-destructive-foreground",
+  info: "bg-info text-info-foreground",
+  warning: "bg-warning text-warning-foreground",
 };
 
 const progressBarStyles = {
-  success: "bg-emerald-500",
-  error: "bg-red-500",
-  info: "bg-blue-500",
-  warning: "bg-amber-500",
+  success: "bg-success",
+  error: "bg-destructive",
+  info: "bg-info",
+  warning: "bg-warning",
 };
 
 export function ToastItem({ toast, onClose }: ToastProps) {
diff --git a/lib/builtin-themes.ts b/lib/builtin-themes.ts
index 7ed880b6..05326cf7 100644
--- a/lib/builtin-themes.ts
+++ b/lib/builtin-themes.ts
@@ -1,5 +1,87 @@
 import type { InstalledTheme } from './plugin-types';
 
+const quiCSS = `
+:root {
+  --color-border: #e4e4e7;
+  --color-input: #e4e4e7;
+  --color-ring: #3b82f6;
+  --color-background: #ffffff;
+  --color-foreground: #09090b;
+  --color-primary: #3b82f6;
+  --color-primary-foreground: #ffffff;
+  --color-secondary: #f4f4f5;
+  --color-secondary-foreground: #18181b;
+  --color-muted: #f4f4f5;
+  --color-muted-foreground: #71717a;
+  --color-accent: #dbeafe;
+  --color-accent-foreground: #1d4ed8;
+  --color-destructive: #ef4444;
+  --color-destructive-foreground: #ffffff;
+  --color-popover: #ffffff;
+  --color-popover-foreground: #09090b;
+  --color-sidebar: #fafafa;
+  --color-sidebar-foreground: #09090b;
+  --color-sidebar-border: #e4e4e7;
+  --color-sidebar-accent: #f4f4f5;
+  --color-sidebar-accent-foreground: #18181b;
+  --color-card: #ffffff;
+  --color-card-foreground: #09090b;
+  --color-success: #22c55e;
+  --color-success-foreground: #ffffff;
+  --color-warning: #eab308;
+  --color-warning-foreground: #ffffff;
+  --color-info: #3b82f6;
+  --color-info-foreground: #ffffff;
+  --color-selection: #dbeafe;
+  --color-selection-foreground: #1d4ed8;
+  --color-unread: #3b82f6;
+  --color-chart-1: #3b82f6;
+  --color-chart-2: #22c55e;
+  --color-chart-3: #f59e0b;
+  --color-chart-4: #ef4444;
+  --color-chart-5: #8b5cf6;
+}
+.dark {
+  --color-border: #27272a;
+  --color-input: #27272a;
+  --color-ring: #3b82f6;
+  --color-background: #09090b;
+  --color-foreground: #fafafa;
+  --color-primary: #3b82f6;
+  --color-primary-foreground: #ffffff;
+  --color-secondary: #18181b;
+  --color-secondary-foreground: #fafafa;
+  --color-muted: #18181b;
+  --color-muted-foreground: #a1a1aa;
+  --color-accent: #172554;
+  --color-accent-foreground: #93c5fd;
+  --color-destructive: #ef4444;
+  --color-destructive-foreground: #fafafa;
+  --color-popover: #18181b;
+  --color-popover-foreground: #fafafa;
+  --color-sidebar: #09090b;
+  --color-sidebar-foreground: #fafafa;
+  --color-sidebar-border: #27272a;
+  --color-sidebar-accent: #18181b;
+  --color-sidebar-accent-foreground: #fafafa;
+  --color-card: #141414;
+  --color-card-foreground: #fafafa;
+  --color-success: #16a34a;
+  --color-success-foreground: #ffffff;
+  --color-warning: #ca8a04;
+  --color-warning-foreground: #ffffff;
+  --color-info: #60a5fa;
+  --color-info-foreground: #ffffff;
+  --color-selection: rgba(59, 130, 246, 0.25);
+  --color-selection-foreground: #93c5fd;
+  --color-unread: #60a5fa;
+  --color-chart-1: #60a5fa;
+  --color-chart-2: #4ade80;
+  --color-chart-3: #fbbf24;
+  --color-chart-4: #f87171;
+  --color-chart-5: #a78bfa;
+}`;
+
 const nordCSS = `
 :root {
   --color-border: #d8dee9;
@@ -19,6 +101,27 @@ const nordCSS = `
   --color-destructive-foreground: #eceff4;
   --color-popover: #eceff4;
   --color-popover-foreground: #2e3440;
+  --color-sidebar: #e5e9f0;
+  --color-sidebar-foreground: #2e3440;
+  --color-sidebar-border: #d8dee9;
+  --color-sidebar-accent: #d8dee9;
+  --color-sidebar-accent-foreground: #2e3440;
+  --color-card: #eceff4;
+  --color-card-foreground: #2e3440;
+  --color-success: #a3be8c;
+  --color-success-foreground: #2e3440;
+  --color-warning: #ebcb8b;
+  --color-warning-foreground: #2e3440;
+  --color-info: #81a1c1;
+  --color-info-foreground: #eceff4;
+  --color-selection: #d8dee9;
+  --color-selection-foreground: #5e81ac;
+  --color-unread: #5e81ac;
+  --color-chart-1: #5e81ac;
+  --color-chart-2: #a3be8c;
+  --color-chart-3: #ebcb8b;
+  --color-chart-4: #bf616a;
+  --color-chart-5: #b48ead;
 }
 .dark {
   --color-border: #3b4252;
@@ -38,6 +141,27 @@ const nordCSS = `
   --color-destructive-foreground: #eceff4;
   --color-popover: #3b4252;
   --color-popover-foreground: #eceff4;
+  --color-sidebar: #2e3440;
+  --color-sidebar-foreground: #eceff4;
+  --color-sidebar-border: #3b4252;
+  --color-sidebar-accent: #3b4252;
+  --color-sidebar-accent-foreground: #eceff4;
+  --color-card: #3b4252;
+  --color-card-foreground: #eceff4;
+  --color-success: #a3be8c;
+  --color-success-foreground: #2e3440;
+  --color-warning: #ebcb8b;
+  --color-warning-foreground: #2e3440;
+  --color-info: #88c0d0;
+  --color-info-foreground: #2e3440;
+  --color-selection: rgba(136, 192, 208, 0.2);
+  --color-selection-foreground: #88c0d0;
+  --color-unread: #88c0d0;
+  --color-chart-1: #88c0d0;
+  --color-chart-2: #a3be8c;
+  --color-chart-3: #ebcb8b;
+  --color-chart-4: #bf616a;
+  --color-chart-5: #b48ead;
 }`;
 
 const catppuccinCSS = `
@@ -59,6 +183,27 @@ const catppuccinCSS = `
   --color-destructive-foreground: #eff1f5;
   --color-popover: #eff1f5;
   --color-popover-foreground: #4c4f69;
+  --color-sidebar: #e6e9ef;
+  --color-sidebar-foreground: #4c4f69;
+  --color-sidebar-border: #ccd0da;
+  --color-sidebar-accent: #dce0e8;
+  --color-sidebar-accent-foreground: #4c4f69;
+  --color-card: #eff1f5;
+  --color-card-foreground: #4c4f69;
+  --color-success: #40a02b;
+  --color-success-foreground: #eff1f5;
+  --color-warning: #df8e1d;
+  --color-warning-foreground: #eff1f5;
+  --color-info: #1e66f5;
+  --color-info-foreground: #eff1f5;
+  --color-selection: #dce0e8;
+  --color-selection-foreground: #8839ef;
+  --color-unread: #8839ef;
+  --color-chart-1: #8839ef;
+  --color-chart-2: #40a02b;
+  --color-chart-3: #df8e1d;
+  --color-chart-4: #d20f39;
+  --color-chart-5: #1e66f5;
 }
 .dark {
   --color-border: #45475a;
@@ -78,6 +223,27 @@ const catppuccinCSS = `
   --color-destructive-foreground: #1e1e2e;
   --color-popover: #313244;
   --color-popover-foreground: #cdd6f4;
+  --color-sidebar: #1e1e2e;
+  --color-sidebar-foreground: #cdd6f4;
+  --color-sidebar-border: #45475a;
+  --color-sidebar-accent: #313244;
+  --color-sidebar-accent-foreground: #cdd6f4;
+  --color-card: #313244;
+  --color-card-foreground: #cdd6f4;
+  --color-success: #a6e3a1;
+  --color-success-foreground: #1e1e2e;
+  --color-warning: #f9e2af;
+  --color-warning-foreground: #1e1e2e;
+  --color-info: #89b4fa;
+  --color-info-foreground: #1e1e2e;
+  --color-selection: rgba(203, 166, 247, 0.2);
+  --color-selection-foreground: #cba6f7;
+  --color-unread: #cba6f7;
+  --color-chart-1: #cba6f7;
+  --color-chart-2: #a6e3a1;
+  --color-chart-3: #f9e2af;
+  --color-chart-4: #f38ba8;
+  --color-chart-5: #89b4fa;
 }`;
 
 const solarizedCSS = `
@@ -99,6 +265,27 @@ const solarizedCSS = `
   --color-destructive-foreground: #fdf6e3;
   --color-popover: #fdf6e3;
   --color-popover-foreground: #657b83;
+  --color-sidebar: #eee8d5;
+  --color-sidebar-foreground: #657b83;
+  --color-sidebar-border: #eee8d5;
+  --color-sidebar-accent: #eee8d5;
+  --color-sidebar-accent-foreground: #586e75;
+  --color-card: #fdf6e3;
+  --color-card-foreground: #657b83;
+  --color-success: #859900;
+  --color-success-foreground: #fdf6e3;
+  --color-warning: #b58900;
+  --color-warning-foreground: #fdf6e3;
+  --color-info: #268bd2;
+  --color-info-foreground: #fdf6e3;
+  --color-selection: #eee8d5;
+  --color-selection-foreground: #268bd2;
+  --color-unread: #268bd2;
+  --color-chart-1: #268bd2;
+  --color-chart-2: #859900;
+  --color-chart-3: #b58900;
+  --color-chart-4: #dc322f;
+  --color-chart-5: #6c71c4;
 }
 .dark {
   --color-border: #073642;
@@ -118,9 +305,41 @@ const solarizedCSS = `
   --color-destructive-foreground: #fdf6e3;
   --color-popover: #073642;
   --color-popover-foreground: #93a1a1;
+  --color-sidebar: #002b36;
+  --color-sidebar-foreground: #839496;
+  --color-sidebar-border: #073642;
+  --color-sidebar-accent: #073642;
+  --color-sidebar-accent-foreground: #93a1a1;
+  --color-card: #073642;
+  --color-card-foreground: #93a1a1;
+  --color-success: #859900;
+  --color-success-foreground: #002b36;
+  --color-warning: #b58900;
+  --color-warning-foreground: #002b36;
+  --color-info: #268bd2;
+  --color-info-foreground: #002b36;
+  --color-selection: rgba(38, 139, 210, 0.2);
+  --color-selection-foreground: #268bd2;
+  --color-unread: #268bd2;
+  --color-chart-1: #268bd2;
+  --color-chart-2: #859900;
+  --color-chart-3: #b58900;
+  --color-chart-4: #dc322f;
+  --color-chart-5: #6c71c4;
 }`;
 
 export const BUILTIN_THEMES: InstalledTheme[] = [
+  {
+    id: 'builtin-qui',
+    name: 'Qui',
+    version: '1.0.0',
+    author: 'Built-in',
+    description: 'Clean, modern zinc-and-blue theme inspired by autobrr/qui',
+    css: quiCSS,
+    variants: ['light', 'dark'],
+    enabled: true,
+    builtIn: true,
+  },
   {
     id: 'builtin-nord',
     name: 'Nord',
diff --git a/lib/email-headers.ts b/lib/email-headers.ts
index d652cd2f..652803df 100644
--- a/lib/email-headers.ts
+++ b/lib/email-headers.ts
@@ -154,10 +154,10 @@ export function getSecurityStatus(result?: string): {
     case 'neutral':
     case 'temperror':
       return {
-        color: 'text-amber-700 dark:text-amber-400',
+        color: 'text-warning',
         icon: 'alert',
         bgColor: 'bg-gray-50 dark:bg-gray-800',
-        borderColor: 'border-l-4 border-amber-600 dark:border-amber-500'
+        borderColor: 'border-l-4 border-warning'
       };
     default:
       return {