tour: The TOC is not scrollable on Firefox

[cbelhaoues]

Context: https://tour.golang.org/welcome/1

The TOC is not scrollable in Firefox, it works fine in Chrome.

[ALTree]

Thanks for the report.

Reproduced with Firefox 68 on Linux. When the TOC is opened, a scrollbar appears, but the mouse wheel does not move it; OTOH if you grab the bar with the mouse and scroll it, it works.

[mozew]

this style will solve the problem (can use extensions like "stylus" until it's fixed):
.toc > ul { position: relative; z-index: 1; }