RZ-BY/Leitfaden-Barrierefreiheit A comprehensive guide to accessibility from a university. This is publicly shared on Github.
AccessAbility 2: A Practical Handbook on Accessible Graphic Design A practical handbook for accessible graphic design.
How to Make Custom Accessible Checkboxes and Radio Buttons It takes a little more to redesign the standard appearance of the form fields checkbox and radio button. The instructions show an accessible solution.
Can I email… Similar to caniuse.com, caniemail.com can be used to check whether features are supported and by which e-mail clients.