Lange - Fixed Header Bar

Site URL: http://www.billydupee.co.uk

Hi there, I am using Lange template and my site is looking great. I just want to make the header fixed at the top of each page when I scroll. I am using Business package so would love to know the code to make this happen. 

Here is an example of a page on my site where the header disappears as you scroll:

https://www.billydupee.co.uk/production-reel-1

Thanks

Add to Home > Design > Custom CSS

header#header {
    position: fixed;
    top: 0;
    left: 0;
    right: 0;
    z-index: 999;
    background: white;
    padding-bottom: 10px;
}