Go to the home page and type in your blog CSS. To preview, hit the escape key on your keyboard. To go back to your code, hit the escape key again. Any code written on this website is automatically saved through your browser.
SealsRock12 and I were working on a project, where, you can use your IDE to edit your code, then auto refreshes to show the preview. However, I thought it might be easier if users can go to one site and start making CSS. Credits to them for getting code the AoPS site (codemirrorEdited.css, community_common.css, feed.css, hyperion.css, main.css, aopsmods.js, codemirror-compressed.js, skulpt.min.js, skulpt-stdlib.js).