*** Issue solved by clearing Chrome's cache ***
On the mobile version of the site, the main menu and search buttons (top left and right) no longer seem to do anything for me. They were working fine, I first noticed this issue around 2 weeks ago. The GB logo in the top center between the buttons is still intractable just fine.
I'm using a Nexus 4, with this software:
Android 4.4.3; Nexus 4 Build/KTU84L