Please fix color contrast issues in the demo

[mgifford]

Describe the bug The demo page should be check for color contrast and have accessibility issues fixed.

To Reproduce If you go here joshuajohnson.co.uk/choices/

Run https://wave.webaim.org/ on it and you see a great many contrast errors because of the painful choice of colors.

Expected behavior There should be clear and readable. Should comply with https://webaim.org/articles/contrast/

Screenshots