Is there a CMS system can be used with HTML

I am working on a portfolio website for a client where they need to be able to upload their work: videos and photos, and some text with (title, short description). Normally I would make such a website with a system like Wordpress, however, the way the website would work is not possible to build with Wordpress (unusual navigation and a more dynamic/animated way to switch between pages). So, I want to build this website by HTML and then connect a CMS system where they can upload their work, which will then properly loaded into HTML pages. I have tried to google solutions, but I cannot find a good approach/tool to do this. Does anyone have a good recommendation for me? Thank in advance, Jip Asveld