First of all, I have searched the forums.
I am trying to understand how the profile customiser functions. I understand how it stores the CSS in the database but I have not been able to locate where the custom CSS gets applied from the database to the profile page. My guess was that somewhere in the code for creating and displaying the profile page is a function that checks to see if a custom profile CSS is stored, then runs a MySQL query to pull out the CSS code from bx_profile_custom_main, translate it to standard CSS and then apply it to the page. However, my guess could be wrong.