- Click the Edit drop-down menu from within any document.
- Choose Edit CSS and a dialog box will appear.
- Just plug in your CSS text to create styles!
*At this time, you won't be able to use external image URLs within the Edit CSS dialog box. Instead, you'll need to import these images to a doc and then find the Docs id within the Edit HTML dialog box. Just use that unique image id and insert that into your CSS dialog box
*Using CSS requires advanced knowledge and is not for users unfamiliar with this languageFinally, there is a help page in the Google Docs user forum which will provide some guidance and examples for using CSS in Docs. Check it out here.