Throughout Sakai 11 there are colours that do not have a high enough ratio. This could be fixed locally, but the default should universally accessible and set a good precedent for local appearance modifications.
As per WCAG, text less than 18 point or bold text less than 14 point must have a luminosity contrast ratio of 4.5:1 or more. Text 18 point or larger or bold text 14 point or larger must have a luminosity contrast ratio of 3:1 or more/
WebAIM has a good colour checker http://webaim.org/resources/contrastchecker/ and most web browser's addon "stores" have tools to aumotate this (for example, WebAIM's Chrome addon).