Note To help you meet visual accessibility standards, there is a built-in WCAG (Web Content Accessibility Guideline) checker on the color selection page. Be aware that if you choose a shade that does not meet these guidelines (for example, the contrast between the text color and the background color is too low), the 
 check mark by  WCAG AA will be replaced by a 
 warning or 
 error icon to alert you to possible accessibility issues. See Customizing colors [1] for more information.
Links:
[1] http://staging.docs.d2l/en/screen-magnifiers-zooming-color-contrast-tips#customizing_colors
[2] http://staging.docs.d2l/en/taxonomy/term/3