feat: add collapsible details to calendar invitation banner and update sanitization config for iframe rendering

components/email/calendar-invitation-banner.tsx

@@ -15,6 +15,7 @@ import {
   X,
   AlertCircle,
   ChevronDown,
+  ChevronUp,
 } from 'lucide-react';
 import { useTranslations, useFormatter } from 'next-intl';
 import { useRouter } from '@/i18n/navigation';
@@ -372,6 +373,7 @@ export function CalendarInvitationBanner({ email }: CalendarInvitationBannerProp
   const [showCalendarPicker, setShowCalendarPicker] = useState(false);
   const [selectedCalendarId, setSelectedCalendarId] = useState<string>('');
   const [rawIcsMethod, setRawIcsMethod] = useState<InvitationMethod>('unknown');
+  const [isCollapsed, setIsCollapsed] = useState(true);
 
   const attachment = findCalendarAttachment(email);
 
@@ -442,6 +444,8 @@ export function CalendarInvitationBanner({ email }: CalendarInvitationBannerProp
   const summary = parsedEvent ? formatEventSummary(parsedEvent) : null;
   const isCancellation = method === 'cancel';
   const isResponseOnly = method === 'reply' || method === 'refresh' || method === 'counter' || method === 'declinecounter';
+  const canCollapse = method === 'reply';
+  const showDetails = !canCollapse || !isCollapsed;
   const allowsRsvp = method === 'request';
   const allowsImport = method === 'request' || method === 'publish' || method === 'add' || method === 'unknown';
 
@@ -750,9 +754,22 @@ export function CalendarInvitationBanner({ email }: CalendarInvitationBannerProp
           )}
           <span className="text-sm font-medium text-foreground truncate">{bannerTitle}</span>
         </div>
+        {canCollapse && (
+          <button
+            type="button"
+            onClick={() => setIsCollapsed((prev) => !prev)}
+            aria-expanded={!isCollapsed}
+            aria-label={isCollapsed ? t('expand') : t('collapse')}
+            title={isCollapsed ? t('expand') : t('collapse')}
+            className="p-1 rounded-md text-muted-foreground hover:text-foreground hover:bg-muted/50 transition-colors flex-shrink-0"
+          >
+            {isCollapsed ? <ChevronDown className="w-4 h-4" /> : <ChevronUp className="w-4 h-4" />}
+          </button>
+        )}
       </div>
 
       {/* Content */}
+      {showDetails && (
       <div className="px-4 py-3 space-y-2.5">
         <div className="lg:flex lg:gap-6">
           {/* Left: Event info */}
@@ -894,8 +911,10 @@ export function CalendarInvitationBanner({ email }: CalendarInvitationBannerProp
           </div>
         )}
       </div>
+      )}
 
       {/* Actions */}
+      {showDetails && (
       <div className="px-4 py-2.5 border-t border-border bg-muted/20 flex items-center gap-2 flex-wrap">
         {canRespond && (
           <>
@@ -1020,6 +1039,7 @@ export function CalendarInvitationBanner({ email }: CalendarInvitationBannerProp
           <Loader2 className="w-4 h-4 animate-spin text-muted-foreground ml-auto" />
         )}
       </div>
+      )}
     </div>
   );
 }

components/email/email-viewer.tsx

@@ -4,7 +4,7 @@ import { useState, useEffect, useLayoutEffect, useMemo, useRef, useCallback } fr
 import ReactDOM from "react-dom";
 import DOMPurify from "dompurify";
 import { Email, ContactCard, Mailbox } from "@/lib/jmap/types";
-import { EMAIL_SANITIZE_CONFIG, collapseBlockedImageContainers, plainTextToSafeHtml } from "@/lib/email-sanitization";
+import { EMAIL_IFRAME_SANITIZE_CONFIG, collapseBlockedImageContainers, plainTextToSafeHtml } from "@/lib/email-sanitization";
 import { hasMeaningfulHtmlBody } from "@/lib/signature-utils";
 import { Button } from "@/components/ui/button";
 import { Avatar } from "@/components/ui/avatar";
@@ -2322,7 +2322,7 @@ export function EmailViewer({
         let blockedExternalContent = false;
 
         // Use shared sanitization config as base (more secure)
-        const sanitizeConfig = { ...EMAIL_SANITIZE_CONFIG };
+        const sanitizeConfig = { ...EMAIL_IFRAME_SANITIZE_CONFIG };
 
         // Check if sender is trusted (localStorage list or address book)
         const senderEmail = email.from?.[0]?.email?.toLowerCase();
@@ -2438,7 +2438,7 @@ export function EmailViewer({
           return cidBlobUrls[cidRef] || 'data:image/gif;base64,R0lGODlhAQABAIAAAAAAAP///yH5BAEAAAAALAAAAAABAAEAAAIBRAA7';
         }
       );
-      const cleanHtml = DOMPurify.sanitize(htmlWithCidUrls, EMAIL_SANITIZE_CONFIG);
+      const cleanHtml = DOMPurify.sanitize(htmlWithCidUrls, EMAIL_IFRAME_SANITIZE_CONFIG);
       return { html: cleanHtml, isHtml: true };
     }
     if (smimeDecryptedText) {
@@ -2446,7 +2446,7 @@ export function EmailViewer({
     }
     // TNEF (winmail.dat) extracted content
     if (tnefHtml) {
-      const cleanHtml = DOMPurify.sanitize(tnefHtml, EMAIL_SANITIZE_CONFIG);
+      const cleanHtml = DOMPurify.sanitize(tnefHtml, EMAIL_IFRAME_SANITIZE_CONFIG);
       return { html: cleanHtml, isHtml: true };
     }
     if (tnefText) {
@@ -2454,7 +2454,7 @@ export function EmailViewer({
     }
     // Embedded message/rfc822 unwrapped content
     if (embeddedEmailHtml) {
-      const cleanHtml = DOMPurify.sanitize(embeddedEmailHtml, EMAIL_SANITIZE_CONFIG);
+      const cleanHtml = DOMPurify.sanitize(embeddedEmailHtml, EMAIL_IFRAME_SANITIZE_CONFIG);
       return { html: cleanHtml, isHtml: true };
     }
     if (embeddedEmailText) {
@@ -2603,7 +2603,7 @@ export function EmailViewer({
     return `<!DOCTYPE html>
 <html style="color-scheme: ${colorScheme};"><head><meta charset="utf-8"><meta name="viewport" content="width=device-width, initial-scale=1">
 <style>
-  body { margin: 0; padding: 16px; font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, sans-serif; font-size: 14px; line-height: 1.6; color: #1a1a1a; background: #ffffff; word-wrap: break-word; overflow-wrap: break-word; }
+  body { margin: 0; padding: 0; font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, sans-serif; font-size: 14px; line-height: 1.6; color: #1a1a1a; background: #ffffff; word-wrap: break-word; overflow-wrap: break-word; }
   img { max-width: 100% !important; height: auto !important; }
   a { color: #1a73e8; }
   table { max-width: 100% !important; table-layout: auto; overflow-wrap: break-word; }

lib/email-sanitization.ts

@@ -36,6 +36,26 @@ export function sanitizeEmailHtml(html: string): string {
   return DOMPurify.sanitize(html, EMAIL_SANITIZE_CONFIG);
 }
 
+/**
+ * Sanitize config for emails rendered inside a sandboxed iframe.
+ * Allows <style> tags because CSS is scoped to the iframe document and
+ * cannot leak into the host app. Scripts are still blocked by the sandbox
+ * attribute (no allow-scripts). Use ONLY for iframe-rendered content —
+ * never for content rendered into the main DOM.
+ */
+export const EMAIL_IFRAME_SANITIZE_CONFIG = {
+  ...EMAIL_SANITIZE_CONFIG,
+  FORBID_TAGS: EMAIL_SANITIZE_CONFIG.FORBID_TAGS.filter((t) => t !== 'style'),
+};
+
+/**
+ * Sanitize email HTML for rendering inside a sandboxed iframe.
+ * Preserves <style> tags so the email's own CSS is applied.
+ */
+export function sanitizeEmailHtmlForIframe(html: string): string {
+  return DOMPurify.sanitize(html, EMAIL_IFRAME_SANITIZE_CONFIG);
+}
+
 /**
  * Sanitize HTML signature with stricter rules
  * Only allows basic formatting, no external resources

locales/en/common.json

@@ -426,7 +426,9 @@
       "cancel_info": "The organizer has cancelled this event.",
       "event_updated": "Update #{sequence}",
       "event_status_tentative": "Tentative",
-      "event_status_cancelled": "Cancelled"
+      "event_status_cancelled": "Cancelled",
+      "expand": "Show details",
+      "collapse": "Hide details"
     },
     "send": "Send",
     "more": "more"