The majority of the CSS properties in red are either no longer supported or not needed. Browsers are moving away from vendor prefixes and the majority of the ones in red (that are useful) have long since been un-prefixed.
For example; moz-border-radius hasn't been needed since Firefox 3.6 (firefox is on version 35 now), moz-opacity was never needed in a shipping release of Firefox, it was only used in a beta version, a lot of the Flexbox ones mentioned are not using that syntax anymore so it's better that they are not included.
From what I can see the only useful CSS properties in use today that are not currently included in WeBuilder's 'cssdefs' are:
clip-path:
user-select:
zoom:
-webkit-font-smoothing:
-moz-osx-font-smoothing:
-ms-touch-action:
-webkit-text-size-adjust:
-ms-text-size-adjust:
Are there any others that you actually use not included?
The stylesheet you created doesn't include some useful new properties like Flexbox.
Here's a great, very up-to-date list of all CSS properties:
http://tympanus.net/codrops/css_referen ... s-property