Index: gc_lang/fr/webext/content_scripts/menu.css
==================================================================
--- gc_lang/fr/webext/content_scripts/menu.css
+++ gc_lang/fr/webext/content_scripts/menu.css
@@ -17,11 +17,11 @@
     border-bottom: 4px solid hsla(210, 100%, 40%, .7);
     border-radius: 50%;
     text-align: center;
     cursor: pointer;
     box-shadow: 0 0 0 0 hsla(210, 50%, 50%, .5);
-    z-index: 2147483640; /* maximum is 2147483647: https://stackoverflow.com/questions/491052/minimum-and-maximum-value-of-z-index */
+    /*z-index: 2147483640; /* maximum is 2147483647: https://stackoverflow.com/questions/491052/minimum-and-maximum-value-of-z-index */
     animation: grammalecte-spin 2s ease 1;
 }
 .grammalecte_menu_main_button:hover {
     border: 4px solid hsla(210, 80%, 35%, .5);
     background-color: hsla(210, 80%, 55%, .5);

Index: gc_lang/fr/webext/content_scripts/menu.js
==================================================================
--- gc_lang/fr/webext/content_scripts/menu.js
+++ gc_lang/fr/webext/content_scripts/menu.js
@@ -7,10 +7,11 @@
 
     constructor (nMenu, xNode) {
         this.sMenuId = "grammalecte_menu" + nMenu;
         this.xButton = oGrammalecte.createNode("div", {className: "grammalecte_menu_main_button", textContent: " "});
         this.xButton.onclick = () => { this.switchMenu(); };
+        this.xButton.style.zIndex = (xNode.style.zIndex.search(/^[0-9]+$/) !== -1) ? (parseInt(xNode.style.zIndex) + 1).toString() : xNode.style.zIndex;
         this.xMenu = this._createMenu(xNode);
         this._insertAfter(this.xButton, xNode);
         this._insertAfter(this.xMenu, xNode);
     }