Change date-button position: {absolute => fixed}.

date-button/index.js

 // ==UserScript==
 // @name        Date Button
 // @namespace   http://hugo.hornquist.se
-// @version     0.1.5
+// @version     0.1.6
 // @author      hugo@lysator.liu.se
 // @match       *://*/*
 // @description Inputs the current date into the current text field.
@@ -106,7 +106,7 @@
     let style = document.createElement('style');
     style.textContent = `
     #${btn_id} {
-        position: absolute;
+        position: fixed;
         top: 1em;
         left: 1em;
         z-index: 10000;