How to make a themeable web application using CSS?

Question

I have an idea for a web application that would allow users to create their own profile pages, and apply custom or pre-defined themes to change the look/feel of their profile page. It would be similar to Wordpress themes, or any other product that utilizes a similar idea. My idea was to build the css using less. The users would be able to create/edit their own themes through a GUI interface (pick colors, fonts, etc). When saving a theme, it would update the variables in the .less files, and rebuild the css accordingly.

Is this a feasible or even possible way to apply style themes to a page? Are there any existing solutions out there that already accomplish this?

Answer 1

One problem i see here is that the user can change other parts of the page which shouldn't be changeable. For examlpe menus, login buttons etc. This could be a security problem. So you must limit the users ways how to change the styles. For example only allow to change certain classes with certain params.