Update css.html

Missing word "in" in "Someone famous in Source Title"
Set validation states also for addons
Merge pull request #8097 from burnsra/3.0.0-wip-addons

Set validation states also for addons
Merge pull request #8080 from mladenplavsic/patch-2

Update css.html
Merge branch '3.0.0-wip' into 3.0.0-sass-wip
Use scss vars