All links broken

I’ve made some changes to CSS in sela, since when none of my links are working. The home page loads fine, but any attempt to connect to other pages on the site brings up this message: “Page Not Found
The page you are looking for might have been removed, had its name changed, or is temporarily unavailable. Please try the following:

If you typed the page address in the Address bar, make sure that it is spelled correctly.
Click the Back button in your browser to try another link.
Use a search engine like Google to look for information on the Internet.”

The pages section of the dashboard still has all of the pages listed, and says that they are published. I can also get into the page editor to change text but when I click ‘view page’, I just get the same error message

Website is here

Any advice much appreciated

Thanks