[Solved] How big can CMS database be? [closed]

I know this has tons of downvotes, but you can cache your database queries. You can also mimic a CSS file using the header type in PHP. See http://css-tricks.com/css-variables-with-php/

This will allow the browser to cache the CSS file that was generated by PHP & MySQL. This means the database will only be called when the cache expires.

In terms of size you will never reach a limit with what you are describing.

Update

These sort of features are a bit unorthodox, using a cached version of the generated CSS file is basically mandatory.

What you can do is include a text editor within the CMS to edit the CSS file, each user can have their own CSS file that overrides the default one if changed. By letting them edit it directly they can change the layout themselves. You can even limit them to only changing colours / font-sizes etc.