Hi Martin,
Not sure if you customize the template js file or not: /templates/ja_spa/js/template.js
I customize this file a bit (attached file), you can unzip and replace above file (backup old file first).
Then add this custom css:
.scrollDown .t4-header-inner {
position: relative;
}
into the file: /templates/ja_spa/css/custom.css (Create this file if it doesn't exist)