Thanks for the help - I do wish there was a way to click on the file name in the left column (books browser) and say to "link" this file to your book section! Anyway, I'm trying to get the code right but it still isn't working. It's probably my "path" - I always get confused where to use the ../ and when not to. I have my Sigil book file saved in a folder called "Sigil Files" and my css file is style.css. I've tried this code:
<link href="../style.css" rel="stylesheet" type="text/css" />
And I've tried removing the "../" at the front but neither are working! What do I need to change?