x/website: hamburger menu doesn't work on mobile

[Waqas-Shah-42]

The index button ( the 3 lines button) does not work on safari iOS

[seankhliao]

I assume this is golang.org where it also doesn't do anything on my iphone

cc @dmitshur

[gopherbot]

Change https://golang.org/cl/344309 mentions this issue: golang.org: fix hamburger menu

[alex-mous]

This bug also occurs on Chrome on iPhone iOS (ver. 93.0.4577.39).