If you are knowledgeable about CSS you can insert custom style sheet into the page to change the appearance of certain elements, such as fonts, colors, sizes, and object alignment. For more information, you can watch the video below or view the terms at the bottom of the page.
Override CSS Preview Content
The preview content shows up when you preview a new template by going to Design > Pick a Template. Once a new template is selected, it will then be in a Preview mode.
Override CSS Active Content
The active content shows up once you select a template and press the "Use on Live Site" link at the top of the page.