smoother marquee and fixed icon jitter/stutter in firefox

frontend/index.html

@@ -46,6 +46,17 @@
             will-change: transform;
         }
 
+        /* Firefox snaps transforms to device pixels (Bug 739176), causing
+           visible jitter. A no-op filter forces a different compositing path
+           that enables sub-pixel rendering during transform animations. */
+        .browser-firefox .tab-row {
+            filter: blur(0px);
+        }
+
+        .browser-firefox .tab-icon {
+            image-rendering: auto;
+        }
+
         .tab {
             display: inline-flex;
             align-items: center;