diff --git a/static/css/components/proximity-viz.css b/static/css/components/proximity-viz.css
index cd29378..264dc3b 100644
--- a/static/css/components/proximity-viz.css
+++ b/static/css/components/proximity-viz.css
@@ -41,10 +41,6 @@
     }
 }
 
-.radar-sweep {
-    transform-origin: 50% 50%;
-}
-
 /* Radar filter buttons */
 .bt-radar-filter-btn {
     transition: all 0.2s ease;
diff --git a/static/css/index.css b/static/css/index.css
index 44fcfa1..9b7723b 100644
--- a/static/css/index.css
+++ b/static/css/index.css
@@ -4410,7 +4410,8 @@ header h1 .tagline {
 
 /* Bluetooth radar — CSS sweep animation (replaces rAF loop in proximity-radar.js) */
 .bt-radar-sweep {
-    transform-origin: 140px 140px;
+    transform-box: view-box;           /* required for consistent SVG transform-origin in Firefox */
+    transform-origin: 140px 140px;     /* CONFIG.size / 2 = 140 */
     animation: bt-radar-rotate 3s linear infinite;
 }