Closes #2204

Inject-JavaScript-Code.md

@@ -4,4 +4,22 @@ For example, some users want to make an Auto Refresh every X time because the se
 
 ```javascript
 setInterval(function(){location.reload();}, 600000);
-```
+```
+
+An other example is injecting custom CSS (user styles). 
+This can be done with following snippet:
+
+```javascript
+(()=>{ let css=`
+/* START OF STYLE */
+
+* {
+    color: red;
+}
+
+/* END OF STYLE */
+`;
+
+var ss = document.createElement("style");
+ss.type = "text/css"; ss.innerHTML = css;
+document.getElementsByTagName("head")[0].appendChild(ss); })();```