vendor css
Vendor CSS usually refers to code that is browser specific. Typically
prefixes:
-webkit- (Chrome, Safari, newer versions of Opera, almost all iOS browsers including Firefox for iOS; basically, any WebKit based browser)
-moz- (Firefox)
-o- (old pre-WebKit versions of Opera)
-ms- (Internet Explorer and Microsoft Edge)
They exist to allow browsers have users use new features in testing.