You can now customize your profile. You need to know or learn CSS basics. Go to where you edit your account, then you will see the Custom CSS menu option. Save standard, compliant CSS there. If you go to your profile and do not see any changes then your CSS is incorrect, or you may need to add the !important property.

For example:

body {
background-color: red !important;

That will change your profile background color to red. However, if you opt to change your background color then you will have many other changes to make so that your profile remains legible.

I may create a full tutorial down the road. In the meantime, you may leave a comment here and share your CSS rules and tricks with other members.