[webvtt] Pull Request: Fix #234: Use a default background for <rt>

zcorpan has just submitted a new pull request for 
https://github.com/w3c/webvtt:

== Fix #234: Use a default background for <rt> ==
The ruby text is rendered outside the background box, so by default,
if the video is white or very bright, the ruby text would be 
unreadable.

See https://github.com/w3c/webvtt/pull/239

Received on Thursday, 5 November 2015 13:15:09 UTC