HTML and CSS post: CSS removed

I've been working on CSS for an art thread for a couple days, but when I went to post it (having copied all my HTML into the code box including the link to my CSS page), all my divs, classes, and IDs were completely removed and so was the link to the style sheet, leaving me with nothing but the raw HTML (h1, p, images). I edited a few times trying to copy the working HTML back into the code editor, but all my selectors keep getting automatically removed so I can't style anything.

Is there something I'm not clicking? or some setting I need to change?

Update: whenever I exit the code view I see the styling as I intended it within the text box, but as soon as I click edit all the styling goes away.

Unfortunately the text editor is notoriously buggy, but I think the div & stylesheet stripping is intentional; all the forum code I’ve seen, including Tetra’s CSS guide, uses HTML tables with inline styles to make things look different. Soo you’ll probably have to copy/paste the styles manually into each element like that :,D