Improve mobile markup on a docs page

[circus2271]

second tap on mobile version-switcher doesn't necessarily close the menu

hover.mp4

this happens because of hover
(tap on button toggles "open" class, but there are also very similar styles which append on hover
so, if button already doesn't have "open" class, it may still be open due to hover styles)

the fix is to remove hover for mobile and turn it on only for desktops (width >= 1200px)