chromium/third_party/blink/web_tests/external/wpt/html/semantics/embedded-content/media-elements/track/track-element/resources/class.vtt

WEBVTT
Cue text fragment with <c> class markup is mapped to HTML <span> element with CSS classes.

1
00:00:00.000 --> 00:00:30.500 align:start position:20%
<c.black>Bear is Coming!!!!!</c>

2
00:00:31.000 --> 00:01:00.500 align:start position:20%
<c.green>I said Bear is coming!!!!</c>

3
00:01:01.000 --> 00:02:00.500 align:start position:20%
I said <c.red.uppercase>Bear is coming now</c>!!!!