The meta site looks the same as it always has, and when I go to the site using firefox on a different device, it also looks as usual. Anyone know what I did and how to undo it?
It seems that you simply switched to mobile web by mistake. It is possible to switch between mobile version and full site, currently you can find the switch near the bottom of the page.
In the mobile version, you should click on "full site" to change the interface. When on full site, you can get to mobile version by clicking on "mobile".
Here is a screenshot of the bottom bar from the mobile version:
And this is where to switch to mobile if you are displaying full site: