diff --git a/frontend/src/css/main.css b/frontend/src/css/main.css
index 68e001e..446948d 100644
--- a/frontend/src/css/main.css
+++ b/frontend/src/css/main.css
@@ -16,9 +16,27 @@
 :root {
   --crossfade-duration: 700ms;
   /* Smooth easing: slow start, gentle acceleration, soft landing */
+  /* Chrome/Firefox: Material Design standard easing */
   --crossfade-easing: cubic-bezier(0.4, 0, 0.2, 1);
 }
 
+/* Safari-specific easing - Safari's bezier curve rendering is different,
+   use a simpler curve that Safari handles more smoothly */
+@supports (-webkit-touch-callout: none) {
+  :root {
+    /* Safari: use ease-in-out which Safari renders more consistently */
+    --crossfade-easing: cubic-bezier(0.42, 0, 0.58, 1);
+  }
+}
+
+/* Firefox-specific optimizations */
+@-moz-document url-prefix() {
+  :root {
+    /* Firefox handles the standard easing well, but we can optimize */
+    --crossfade-easing: cubic-bezier(0.4, 0, 0.2, 1);
+  }
+}
+
  
 .introjs-tooltip {
   @apply min-w-[400px] max-w-[480px] p-2 !important;
@@ -90,32 +108,52 @@
   }
 }
 
-/* Crossfade animation classes - GPU accelerated for Safari */
+/* Crossfade animation classes - GPU accelerated for all browsers */
 /* Duration controlled by --crossfade-duration CSS variable (single source of truth) */
 .animate-crossfade-in {
-  /* Explicit initial state prevents Safari flash during animation setup */
+  /* Explicit initial state prevents flash during animation setup */
   opacity: 0;
   -webkit-transform: translate3d(0, 0, 0);
   transform: translate3d(0, 0, 0);
-  -webkit-animation: page-crossfade-in var(--crossfade-duration, 700ms) var(--crossfade-easing, cubic-bezier(0.4, 0, 0.2, 1)) forwards;
-  animation: page-crossfade-in var(--crossfade-duration, 700ms) var(--crossfade-easing, cubic-bezier(0.4, 0, 0.2, 1)) forwards;
+  /* Full animation property for maximum browser compatibility */
+  -webkit-animation-name: page-crossfade-in;
+  animation-name: page-crossfade-in;
+  -webkit-animation-duration: var(--crossfade-duration, 700ms);
+  animation-duration: var(--crossfade-duration, 700ms);
+  -webkit-animation-timing-function: var(--crossfade-easing, cubic-bezier(0.4, 0, 0.2, 1));
+  animation-timing-function: var(--crossfade-easing, cubic-bezier(0.4, 0, 0.2, 1));
+  -webkit-animation-fill-mode: forwards;
+  animation-fill-mode: forwards;
+  -webkit-animation-play-state: running;
+  animation-play-state: running;
   -webkit-backface-visibility: hidden;
   backface-visibility: hidden;
-  /* Only animate opacity - transform is for GPU layer promotion */
+  /* Optimize compositing */
   will-change: opacity;
+  contain: layout style paint;
 }
 
 .animate-crossfade-out {
-  /* Explicit initial state prevents Safari flash during animation setup */
+  /* Explicit initial state prevents flash during animation setup */
   opacity: 1;
   -webkit-transform: translate3d(0, 0, 0);
   transform: translate3d(0, 0, 0);
-  -webkit-animation: page-crossfade-out var(--crossfade-duration, 700ms) var(--crossfade-easing, cubic-bezier(0.4, 0, 0.2, 1)) forwards;
-  animation: page-crossfade-out var(--crossfade-duration, 700ms) var(--crossfade-easing, cubic-bezier(0.4, 0, 0.2, 1)) forwards;
+  /* Full animation property for maximum browser compatibility */
+  -webkit-animation-name: page-crossfade-out;
+  animation-name: page-crossfade-out;
+  -webkit-animation-duration: var(--crossfade-duration, 700ms);
+  animation-duration: var(--crossfade-duration, 700ms);
+  -webkit-animation-timing-function: var(--crossfade-easing, cubic-bezier(0.4, 0, 0.2, 1));
+  animation-timing-function: var(--crossfade-easing, cubic-bezier(0.4, 0, 0.2, 1));
+  -webkit-animation-fill-mode: forwards;
+  animation-fill-mode: forwards;
+  -webkit-animation-play-state: running;
+  animation-play-state: running;
   -webkit-backface-visibility: hidden;
   backface-visibility: hidden;
-  /* Only animate opacity - transform is for GPU layer promotion */
+  /* Optimize compositing */
   will-change: opacity;
+  contain: layout style paint;
 }
 
 /* Safari-specific GPU compositing optimization */
@@ -126,8 +164,22 @@
     -webkit-transform: translate3d(0, 0, 0);
     transform: translate3d(0, 0, 0);
     /* Prevent Safari from optimizing away the GPU layer */
-    -webkit-perspective: 1000;
-    perspective: 1000;
+    -webkit-perspective: 1000px;
+    perspective: 1000px;
+    /* Safari performs better with explicit transform-style */
+    -webkit-transform-style: preserve-3d;
+    transform-style: preserve-3d;
+    /* Isolate the layer for better compositing */
+    isolation: isolate;
+  }
+}
+
+/* Firefox-specific optimizations */
+@-moz-document url-prefix() {
+  .animate-crossfade-in,
+  .animate-crossfade-out {
+    /* Firefox handles animations well but benefits from layer isolation */
+    will-change: opacity, transform;
   }
 }
 
diff --git a/frontend/src/hooks/useBackgroundTransition.ts b/frontend/src/hooks/useBackgroundTransition.ts
index 09c0905..6887e97 100644
--- a/frontend/src/hooks/useBackgroundTransition.ts
+++ b/frontend/src/hooks/useBackgroundTransition.ts
@@ -14,6 +14,11 @@
  * Two modes:
  * 1. fadeIn mode: Crossfade animation for direct (non-video) page navigation
  * 2. fadeOut mode: Legacy support - kept for backwards compatibility but not recommended
+ *
+ * Cross-browser notes:
+ * - Chrome: Uses CSS animations with onAnimationEnd event
+ * - Safari: Uses JS timer fallback (Safari's onAnimationEnd can be unreliable)
+ * - Firefox: Uses CSS animations with onAnimationEnd event
  */
 
 import {
@@ -74,7 +79,7 @@ export interface UseBackgroundTransitionResult {
   /** Whether page content is currently fading (crossfade in progress) */
   isFadingIn: boolean;
   /** Handler to call when fade-in animation ends (pass to onAnimationEnd) */
-  onFadeInAnimationEnd: () => void;
+  onFadeInAnimationEnd: (e?: React.AnimationEvent) => void;
   /** Reset fade-in state (for cleanup or cancellation) */
   resetFadeIn: () => void;
 }
@@ -121,6 +126,11 @@ export function useBackgroundTransition({
   // Track previous isSwitching state to detect transition start
   const wasSwitchingRef = useRef(false);
 
+  // Safari fallback timer ref - Safari's onAnimationEnd can be unreliable
+  const fadeInTimerRef = useRef<ReturnType<typeof setTimeout> | null>(null);
+  // Track if animation was already completed (by event or timer)
+  const fadeInCompletedRef = useRef(false);
+
   /**
    * Reset fade-out state before starting a new transition.
    * This prevents the fade-out effect from re-triggering when state resets.
@@ -134,15 +144,44 @@ export function useBackgroundTransition({
    */
   const resetFadeIn = useCallback(() => {
     setIsFadingIn(false);
+    fadeInCompletedRef.current = false;
+    if (fadeInTimerRef.current) {
+      clearTimeout(fadeInTimerRef.current);
+      fadeInTimerRef.current = null;
+    }
+  }, []);
+
+  /**
+   * Complete fade-in animation.
+   * Called either by onAnimationEnd or by timer fallback.
+   * Uses ref to prevent double-completion.
+   */
+  const completeFadeIn = useCallback(() => {
+    if (fadeInCompletedRef.current) return;
+    fadeInCompletedRef.current = true;
+
+    // Clear backup timer if it exists
+    if (fadeInTimerRef.current) {
+      clearTimeout(fadeInTimerRef.current);
+      fadeInTimerRef.current = null;
+    }
+
+    setIsFadingIn(false);
   }, []);
 
   /**
    * Handler for onAnimationEnd event.
-   * Called when CSS animation completes - CSS is the source of truth for duration.
+   * Called when CSS animation completes.
+   * Uses completeFadeIn to handle deduplication with timer fallback.
    */
-  const onFadeInAnimationEnd = useCallback(() => {
-    setIsFadingIn(false);
-  }, []);
+  const onFadeInAnimationEnd = useCallback(
+    (e?: React.AnimationEvent) => {
+      // Only handle the crossfade animation, not child animations
+      if (e && e.animationName !== 'page-crossfade-in') return;
+      completeFadeIn();
+    },
+    [completeFadeIn],
+  );
 
   /**
    * Effect: Fade out and remove transition overlay when background is ready.
@@ -240,6 +279,10 @@ export function useBackgroundTransition({
    * preventing any flash of new content at full opacity.
    *
    * IMPORTANT: Skip this for transitions - transition video IS the effect.
+   *
+   * Cross-browser handling:
+   * - Sets up JS timer fallback for Safari (unreliable onAnimationEnd)
+   * - Chrome/Firefox rely on CSS onAnimationEnd event
    */
   useLayoutEffect(() => {
     if (!fadeIn) {
@@ -256,9 +299,41 @@ export function useBackgroundTransition({
     // Only start crossfade for NON-transition navigation
     // Transitions use video overlay - no fade needed
     if (justStartedSwitching && !hasActiveTransition) {
+      // Reset completion flag for new animation
+      fadeInCompletedRef.current = false;
+
+      // Clear any existing timer
+      if (fadeInTimerRef.current) {
+        clearTimeout(fadeInTimerRef.current);
+        fadeInTimerRef.current = null;
+      }
+
       setIsFadingIn(true);
+
+      // Safari/Firefox fallback: Use JS timer as backup since onAnimationEnd
+      // can be unreliable or fire on wrong animations.
+      // Timer is slightly longer than CSS duration to let CSS complete first.
+      // Chrome typically fires onAnimationEnd reliably, but timer is harmless backup.
+      const duration = getCrossfadeDuration();
+      // Add 50ms buffer for Safari's animation timing variance
+      const bufferMs = isSafari() ? 100 : 50;
+
+      fadeInTimerRef.current = setTimeout(() => {
+        fadeInTimerRef.current = null;
+        completeFadeIn();
+      }, duration + bufferMs);
     }
-  }, [pageSwitch.isSwitching, fadeIn]);
+  }, [pageSwitch.isSwitching, fadeIn, completeFadeIn]);
+
+  // Cleanup timer on unmount
+  useEffect(() => {
+    return () => {
+      if (fadeInTimerRef.current) {
+        clearTimeout(fadeInTimerRef.current);
+        fadeInTimerRef.current = null;
+      }
+    };
+  }, []);
 
   return {
     isOverlayFadingOut,