Playlist shortcode text is unreadable when using the default light color scheme on themes that have light text.

[kwight]

The default light color scheme for the playlist shortcode inherits its text color from the body element. If a theme has light text over a dark background, the shortcode's text will also be light, but over its own light background.

The attached patch specifies text colors for the light color scheme, making theme color choices irrelevant.

[helen]

In 27805:

Set baseline colors for the light playlist skin. props kwight. fixes #27562.

[nacin]

Reopening for further review; wonderboymusic and I discussed ditching colors nearly entirely and letting the theme do it all. I might have misunderstood, but want to make sure this gets reviewed.

[wonderboymusic]

This appears to be good. Someone reopen if anything else blows up. Similar to [27865], we need to set the basics.