Index: gc_lang/fr/webext/content_scripts/init.js
==================================================================
--- gc_lang/fr/webext/content_scripts/init.js
+++ gc_lang/fr/webext/content_scripts/init.js
@@ -212,10 +212,32 @@
             if (oDataset) {
                 Object.assign(xNode.dataset, oDataset);
             }
             return xNode;
         }
+        catch (e) {
+            showError(e);
+        }
+    },
+
+    createStyle: function (sLinkCss, sLinkId=null, oAppend=null) {
+        try {
+            let xNode = document.createElement("link");
+            Object.assign(xNode, {
+                rel: "stylesheet",
+                type: "text/css",
+                media: "all",
+                href: this.sExtensionUrl + sLinkCss
+            });
+            if (sLinkId) {
+                Object.assign(xNode, {id: sLinkId});
+            }
+            if (oAppend) {
+                oAppend.appendChild(xNode);
+            }
+            return xNode;
+        }
         catch (e) {
             showError(e);
         }
     }
 };

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
@@ -27,29 +27,23 @@
         this.bShadow = document.body.createShadowRoot || document.body.attachShadow;
         if (this.bShadow){
             let nMarginTop = -1 * (parseInt(xStyle.marginBottom.replace('px', ''), 10));
             this.oShadowBtn = oGrammalecte.createNode("div", {style: "display:none;position:absolute;width:0;height:0;"});
             this.oShadowBtnNode = this.oShadowBtn.attachShadow({mode: "open"});
-            this.oShadowBtnNode.appendChild(
-                oGrammalecte.createNode("link", {rel: "stylesheet", type: "text/css", media: "all", href: oGrammalecte.sExtensionUrl + "content_scripts/menu.css"})
-            );
+            oGrammalecte.createStyle("content_scripts/menu.css", null, this.oShadowBtnNode);
             this.oShadowBtnNode.appendChild(this.xButton);
             this._insertAfter(this.oShadowBtn, xNodeInsertAfter, nMarginTop);
 
             this.oShadowMenu = oGrammalecte.createNode("div", {id: this.sMenuId+"_shadow", style: "display:none;position:absolute;width:0;height:0;"});
             this.oShadowMenuNode = this.oShadowMenu.attachShadow({mode: "open"});
-            this.oShadowMenuNode.appendChild(
-                oGrammalecte.createNode("link", {rel: "stylesheet", type: "text/css", media: "all", href: oGrammalecte.sExtensionUrl + "content_scripts/menu.css"})
-            );
+            oGrammalecte.createStyle("content_scripts/menu.css", null, this.oShadowMenuNode);
             this.oShadowMenuNode.appendChild(this.xMenu);
             this._insertAfter(this.oShadowMenu, xNodeInsertAfter, nMarginTop + 8);
         } else {
             let nMarginTop = -1 * (8 + parseInt(xStyle.marginBottom.replace('px', ''), 10));
             if (!document.getElementById("grammalecte_cssmenu")){
-                document.head.appendChild(
-                    oGrammalecte.createNode("link", {id: "grammalecte_cssmenu", rel: "stylesheet", type: "text/css", media: "all", href: oGrammalecte.sExtensionUrl + "content_scripts/menu.css"})
-                );
+                oGrammalecte.createStyle("content_scripts/menu.css", "grammalecte_cssmenu", document.head);
             }
             this._insertAfter(this.xButton, xNodeInsertAfter, nMarginTop);
             this._insertAfter(this.xMenu, xNodeInsertAfter, nMarginTop + 8);
         }
         this._createListeners();

Index: gc_lang/fr/webext/content_scripts/message_box.js
==================================================================
--- gc_lang/fr/webext/content_scripts/message_box.js
+++ gc_lang/fr/webext/content_scripts/message_box.js
@@ -63,26 +63,18 @@
         return xButton;
     }
 
     insertIntoPage () {
         if (this.bShadow){
-            this.oShadow.appendChild(
-                oGrammalecte.createNode("link", {rel: "stylesheet", type: "text/css", media: "all", href: oGrammalecte.sExtensionUrl + "content_scripts/panel.css"})
-            );
-            this.oShadow.appendChild(
-                oGrammalecte.createNode("link", {rel: "stylesheet", type: "text/css", media: "all", href: oGrammalecte.sExtensionUrl + "content_scripts/message_box.css"})
-            );
+            oGrammalecte.createStyle("content_scripts/panel.css", null, this.oShadow);
+            oGrammalecte.createStyle("content_scripts/message_box.css", null, this.oShadow);
             this.oShadow.appendChild(this.xMessageBox);
             document.body.appendChild(this.oShadowPanel);
         } else {
             if (!document.getElementById("grammalecte_cssmsg")){
-                document.head.appendChild(
-                    oGrammalecte.createNode("link", {rel: "stylesheet", type: "text/css", media: "all", href: oGrammalecte.sExtensionUrl + "content_scripts/panel.css"})
-                );
-                document.head.appendChild(
-                    oGrammalecte.createNode("link", {id: "grammalecte_cssmsg", rel: "stylesheet", type: "text/css", media: "all", href: oGrammalecte.sExtensionUrl + "content_scripts/message_box.css"})
-                );
+                oGrammalecte.createStyle("content_scripts/panel.css", null, document.head);
+                oGrammalecte.createStyle("content_scripts/message_box.css", "grammalecte_cssmsg", document.head);
             }
             document.body.appendChild(this.xMessageBox);
         }
     }
 

Index: gc_lang/fr/webext/content_scripts/panel.js
==================================================================
--- gc_lang/fr/webext/content_scripts/panel.js
+++ gc_lang/fr/webext/content_scripts/panel.js
@@ -96,38 +96,22 @@
         return xButton;
     }
 
     insertIntoPage () {
         if (this.bShadow){
-            this.oShadow.appendChild(
-                oGrammalecte.createNode("link", {rel: "stylesheet", type: "text/css", media: "all", href: oGrammalecte.sExtensionUrl + "content_scripts/panel.css"})
-            );
-            this.oShadow.appendChild(
-                oGrammalecte.createNode("link", {rel: "stylesheet", type: "text/css", media: "all", href: oGrammalecte.sExtensionUrl + "content_scripts/panel_gc.css"})
-            );
-            this.oShadow.appendChild(
-                oGrammalecte.createNode("link", {rel: "stylesheet", type: "text/css", media: "all", href: oGrammalecte.sExtensionUrl + "content_scripts/panel_lxg.css"})
-            );
-            this.oShadow.appendChild(
-                oGrammalecte.createNode("link", {rel: "stylesheet", type: "text/css", media: "all", href: oGrammalecte.sExtensionUrl + "content_scripts/panel_tf.css"})
-            );
+            oGrammalecte.createStyle("content_scripts/panel.css", null, this.oShadow);
+            oGrammalecte.createStyle("content_scripts/panel_gc.css", null, this.oShadow);
+            oGrammalecte.createStyle("content_scripts/panel_lxg.css", null, this.oShadow);
+            oGrammalecte.createStyle("content_scripts/panel_tf.css", null, this.oShadow);
             this.oShadow.appendChild(this.xPanel);
             document.body.appendChild(this.oShadowPanel);
         } else {
             if (!document.getElementById("grammalecte_csspanel")){
-                document.head.appendChild(
-                    oGrammalecte.createNode("link", {id: "grammalecte_csspanel", rel: "stylesheet", type: "text/css", media: "all", href: oGrammalecte.sExtensionUrl + "content_scripts/panel.css"})
-                );
-                document.head.appendChild(
-                    oGrammalecte.createNode("link", {rel: "stylesheet", type: "text/css", media: "all", href: oGrammalecte.sExtensionUrl + "content_scripts/panel_gc.css"})
-                );
-                document.head.appendChild(
-                    oGrammalecte.createNode("link", {rel: "stylesheet", type: "text/css", media: "all", href: oGrammalecte.sExtensionUrl + "content_scripts/panel_lxg.css"})
-                );
-                document.head.appendChild(
-                    oGrammalecte.createNode("link", {rel: "stylesheet", type: "text/css", media: "all", href: oGrammalecte.sExtensionUrl + "content_scripts/panel_tf.css"})
-                );
+                oGrammalecte.createStyle("content_scripts/panel.css", "grammalecte_csspanel", document.head);
+                oGrammalecte.createStyle("content_scripts/panel_gc.css", null, document.head);
+                oGrammalecte.createStyle("content_scripts/panel_lxg.css", null, document.head);
+                oGrammalecte.createStyle("content_scripts/panel_tf.css", null, document.head);
             }
             document.body.appendChild(this.xPanel);
         }
     }