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frontend/src/components/common/PageTransition.scss

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+@use '@/styles/variables.scss' as *;
+
+.page-transition {
+  position: relative;
+  flex: 1 1 auto;
+  display: flex;
+  flex-direction: column;
+  min-height: 0;
+  overflow: hidden;
+
+  &__layer {
+    display: flex;
+    flex-direction: column;
+    gap: $spacing-lg;
+    min-height: 0;
+    flex: 1;
+    background: var(--bg-secondary);
+    backface-visibility: hidden;
+    transform: translateZ(0);
+
+    // During animation, exit layer uses absolute positioning
+    &--exit {
+      position: absolute;
+      inset: 0;
+      overflow: hidden;
+      pointer-events: none;
+      will-change: transform, opacity;
+    }
+
+    &--stacked {
+      display: none;
+
+      // Keep the previous layer rendered (but invisible) to avoid a blank flash when popping back.
+      // Older stacked layers remain `display: none` for performance.
+      &.page-transition__layer--stacked-keep {
+        display: flex;
+        position: absolute;
+        inset: 0;
+        overflow: hidden;
+        pointer-events: none;
+        opacity: 0;
+        will-change: transform, opacity;
+      }
+    }
+  }
+
+  &--animating &__layer {
+    will-change: transform, opacity;
+  }
+
+  &--animating &__layer:not(.page-transition__layer--exit):not(.page-transition__layer--stacked) {
+    position: relative;
+  }
+}