Useful web design resources

This is a page with links to some resources I find useful when designing or redesigning this and other websites.

Coolors
A colour scheme generator. This site generates random pallettes of five complementary colours. You can specify your own starter colours and lock the ones you want in.
ColorSpace
Another, simpler colour scheme generator that takes a single colour and generates a large number of different pallettes that incorporate it.
A Complete Guide to Flexbox
A comprehensive article about how CSS flexbox works, detailing and illustrating all permutations and options.