How to edit the CSS of your entire site
You may want to add CSS rules that you want added to every webpage on your site. This is useful for editing the CSS of the header, footer, background of all pages, or any other area that you want edited on all pages of the site.
To add CSS that will be applied to the entire site, please do the following:
Login to the Admin area of your site
Navigate to Settings >> Website Layout in the main top navigation
Scroll down to the “Website CSS” area
Add all of your custom CSS to the textarea here
The CSS added here will override the default CSS of your template. To go back to the default styles, simply delete the CSS here and the styles will be reset to their defaults.
NOTE: be careful when doing this, as your custom CSS will be permanently deleted, and cannot be retrieved!