I actually made this months ago but never shared it, so here it is! To install:
1. Install the Stylish extension.
2. Open this link
3. Go to Stylish's Manage Styles page and create a new style.
4. Click "import" on the sidebar under the Mozilla Format header.
5. Paste everything from the .css file into the textbox.
6. Click "overwrite style" near the bottom.
7. Hit save on the sidebar.
Note that this will probably break when you use any site scheme except for "SMW Central - menu right" (the default). This means that sadly you can't preview it during C3, but you will have to do with the screenshots.
The images are large so i'll link them instead of putting them here directly.