Color and contrast

Contrast ratios illustrated

Normal weight

light weight

high weight

heavy weight

Helvetica Neue Light

Apple's 5.5 contrast

Google's 4.6 contrast

Colours illustrated

There are several ways to specify colours on the web. By name:

The way colours are specified on the web is by supplying numbers for red, green and blue from 0-255. These are expressed as hex digits 0123456789ABCDEF. If the r,g,b match, they're a grey.