What is CSS?
CSS is a computer language used to format/style websites. It specifies where elements are displayed to the colors and font types.
The default CSS of a Silk page can be found by viewing the source of any Silk site, e.g. this one. You'll notice that this "About Silk" site looks very different, so feel free to check out the custom CSS we used for this.
We support custom templates, for those who want to use their own CSS.