MetaLocator supports custom CSS for users in our Pro and higher plans.
CSS can be provided directly in the CSS setting found under Style & Color as shown below:

Click the External Link arrow to “maximize” the CSS editor as shown below:

Click the down arrow to minimize the editor.
Clicking the Save icon applies the CSS changes to the Interface in the Builder, but does not save the Interface.
CSS Best Practices
MetaLocator avoids markup changes to key page structural elements to avoid breaking customer-authored CSS, however; occasionally markup changes can not be avoided.
When authoring CSS, we recommend using the vendor prefix
.metalocator ...your selector here... {
In front of every selector as shown in the screenshot above.
Click the image below for an annotated layout showing each CSS ID and class selector available when styling the layout.
Of course, the best way to find information about the CSS on a Web site is to use an extension like the Web Developer Toolbar or Chrome Inspector or Firebug.