LOL! The best way to test out new journals in future is to go back to an old journal of yours and edit it, putting in all your new CSS ideas in that. At the bottom there is a box that is normally checked, which says something like "THIS EDIT IS MINOR AND YOUR WATCHERS WILL NOT BE NOTIFIED". You only uncheck it (or is it the other way round?? lol!) if you WANT your watchers to be notified of the changes.
Click on the dA logo top left, and where the drop-down list comes out, click on Updat Journal. This takes you to the page where all your journals are in html etc. On the right of each one, you'll see Edit. You can click on that, and get alllllll carried away to your heart's content, lol! Hope that makes sense?
That's the way I do it..