Form element focus style has too low contrast

[hidde]

From w3c/wai-authoring-tools-list#51:

Form element focus styling includes a pale blue block border around the element. The contrast between this and the background colour is 1.1:1, which is below 3:1.

As this is a WAI-wide issue, I'll file it here (I was unable to file it in the @w3c org, feel free to move it there if possible).