To customize the Color Combination of website or to make any visual changes into website you can follow below steps.
Step 1: Click on Manage Websites
Step 2: Click on settings icon of website which you want to modify
Step 3: click on Custom CSS Tab in settings panal
Step 3a: if you want to add custom javascript code you can do that by adding your javascript code into Custom Javascript option
Step 4: Save
All the changes made by you will get reflected on website. if you face any issue please let us know.