Created by: ssorallen
@gray-light darkens from #999 to #777, which puts .text-muted at the
threshold for the 4.5:1 WCAG minimum contrast[1]. #777:#fff is 4.48:1.
The “Example” headers in docs becomes #959595, which is contrast ratio
3:1, the minimum for larger text. Since the headers are less important
than the surrounding text, 3:1 is fine and an improvement on the
previous #bbb:#fff (1.92:1).
Fixes issue #13847 (closed).
[1] http://www.w3.org/TR/UNDERSTANDING-WCAG20/visual-audio-contrast-contrast.html