(requires *nix based install) npm install -g csslint In the base of your moodle install: Run csslint --quiet --format=compact . | grep Error VERIFY: you can only see errors noted in the expected errors section below Run csslint --quiet --format=compact . | grep -v Error VERIFY: the warnings you see generally look sensible, but not overwhelming (considering its the entire codebase) Expected errors theme/(clean|more)/style/custom.css: IDENT errors Caused by our templates in there. Doesn't look to be a away round it except ignoring the whole files. I still think its useful to have these file checked, so we just have to expect the error (cibot will filter them too) base/style/course.css: line 576, col 14, Error - Duplicate property '*display' found. This looks like its an IE7 workaround to me, not touching for safety. (If anyone ever edits that line they can investigate) theme/base/style/filemanager.css: line 21, col 20, Error - Duplicate property 'filter' found theme/base/style/filemanager.css: line 21, col 118, Error - Duplicate property 'background' found. Looks like more crazy IE stuff, same as above