how can i make users edit their own template?

hey,

im not sure if this has been brought up before.

but i was wondering if its possible, or a solution already exists for this.

i want to allow users to register and login, and create their own gallery template, like change their page?

you know blogger.com? theres feature where you can edit the CSS, and completely customize how your page looks.

i want the same feature, like allow users to create their own gallery, and customize their page with CSS and html.