Low contrast on gray items

Description

The text contrast is too low on the gray texts in the page tree and in the meta properties editor.
Customer quote:

After the upgrade to the user interface the contrast ratio is overall not very good. A lot of text and links are no grey-ish text on grey-ish background.
The new interface does not meet the requirements in WCAG: https://webaim.org/blog/wcag-2-0-and-link-colors/ and is difficult to use for a lot of our editors.
Some screenshots that illustrate the problem in the attached document and images.