Expected Behavior:

The colour contrast ratio of text and background needs to be 4.5 or higher according to the WCAG 2.0 and 2.1 guidelines.

This is to ensures that most people can read the text.

Actual Behavior:

The description (.cmb2-metabox-description) has a colour of #aaaaaa which results in a contrast ratio against the white background of 2.3, which is too low.

Steps to reproduce (I have confirmed I can reproduce this issue on the trunk branch):

Check the color contrast with a tool like Colour Contrast Check by Snook

Suggested improvement:

I suggest changing the #aaaaaa in #757575, which has a ratio against white of 4.5.

.cmb2-metabox-description is defined in a few places in the CSS files.