diff --git a/ext/fg/js/popup.js b/ext/fg/js/popup.js
index 398e975e..8e71fefa 100644
--- a/ext/fg/js/popup.js
+++ b/ext/fg/js/popup.js
@@ -38,21 +38,21 @@ class Popup {
     showNextTo(elementRect, content) {
         this.inject();
 
-        const containerRect = this.container.getBoundingClientRect();
+        const containerStyle = window.getComputedStyle(this.container);
+        const containerHeight = parseInt(containerStyle.height);
+        const containerWidth = parseInt(containerStyle.width);
 
         let x = elementRect.left;
-        let width = containerRect.width;
+        let width = containerWidth;
         if (x + width >= window.innerWidth) {
-            const widthMax = window.innerWidth - x;
-            width = Math.min(width, widthMax);
+            width = Math.min(width, x);
             x = window.innerWidth - width;
         }
 
         let y = elementRect.bottom + this.offset;
-        let height = containerRect.height;
+        let height = containerHeight;
         if (y + height >= window.innerHeight) {
-            const heightMax = window.innerHeight - y - this.offset;
-            height = Math.min(height, heightMax);
+            height = Math.min(height, y);
             y = elementRect.top - height - this.offset;
         }