Board Thread:Support Requests - Getting Technical/@comment-25050081-20151029094748/@comment-26437440-20151029183014

Yep, as of right now you can only turn syntax highlighting in source mode on or off.

If it's on you'll get the colors and such, but template pages use the Portable infobox editor. If it's off you don't get syntax highlighting on any pages. This includes JS and CSS pages.