Google’s Search Relations team explains how CSS affects SEO, addressing myths about class names, pseudo elements, and page ...

For example, if you want the page "index.html" to use the CSS template "template.css," then save template.css in the same folder in which you store "index.html." Open the HTML file in a text editor.

It uses a click-and-drag interface for adding content to any page. If you have some CSS know-how or want to look at the source code for your website, Weebly offers an Advanced Editor for CSS and HTML.