fix blank space with plain-text emails

components/email/email-viewer.tsx

@@ -3845,22 +3845,19 @@ export function EmailViewer({
         </Button>
 
         {/* Dark/light mode toggle for HTML emails */}
+        {effectiveEmailContent.isHtml && (
         <Button
           variant="ghost"
           size="sm"
           onClick={() => setEmailViewDarkOverride(prev => prev === null ? !(resolvedTheme === 'dark') : !prev)}
           data-overflow-item
           data-overflow-priority="11"
-          className={cn(
-            "hidden sm:inline-flex h-8 gap-1.5",
-            !effectiveEmailContent.isHtml && "invisible pointer-events-none"
-          )}
+          className="hidden sm:inline-flex h-8 gap-1.5"
           title={isDark ? 'View in light mode' : 'View in dark mode'}
-          tabIndex={effectiveEmailContent.isHtml ? 0 : -1}
-          aria-hidden={!effectiveEmailContent.isHtml}
         >
           {isDark ? <Sun className="w-4 h-4" /> : <Moon className="w-4 h-4" />}
         </Button>
+        )}
 
         {/* More menu - click-based */}
         <div ref={moreMenuRef} className="relative">