Markdown CSS tweaks (#15572)
Markdown CSS tweaks (#15572)

Update Markdown CSS to more closely match GH rendering. Changes include
better nested list margins and tweaked font sizes.

Co-authored-by: Lauris BH <f3041c4c693c07149804ea655e75ee8bb856bd26@nix.lv>
cez81/gitea,cez81/gitea,vdbt/gitea,go-gitea/gitea,go-gitea/gitea,cez81/gitea,vdbt/gitea,go-gitea/gitea