Set z-index for sticky diff box lower (#12537)
Set z-index for sticky diff box lower (#12537)

Fix #12525

Signed-off-by: Andrew Thornton <6a547fdd28db89120bdd70d4af1f9ba672ccd43a@cantab.net>
cez81/gitea,sapk-fork/gitea,cez81/gitea,sapk-fork/gitea,sapk-fork/gitea,go-gitea/gitea,go-gitea/gitea,cez81/gitea,sapk-fork/gitea,vdbt/gitea,go-gitea/gitea,vdbt/gitea