I don’t have a tablet - touch screens are even more problematic than a mouse.
This post rather suggests that “Reply as new topic” is a core Discourse function:
https://meta.discourse.org/t/what-do-user-trust-levels-do/4924/4?u=technobear
and surely all members should be able to access the appropriate facilities for their Trust Level, regardless of whether they are using mouse, keyboard or tablet?
I’m sure SitePoint will sort the CSS issue, but the underlying problem will remain, here and on other Discourse sites.