you can see result now in demo (it can change in future, so look now)
You can get your file here
Left mouse click and Save file as...
I don't have idea how you changed original Gaia, so you can:
- comment loading gaia.css from theme.php (not mandatory, but it useless now to load)
- copy content to custom_style.css if you plan to install future updates of Gaia (it will be overriden with style.css)
- or copy content to style.css directly
Don't forget backup and clear cache.