Why Don't my CSS Colour Styles Work?

Question: Why Don't my CSS Colour Styles Work?
If you speak a variant of British English that has spellings like favourite and colour, you may come into trouble when writing CSS.
Answer: CSS is written with US English spellings. So if you are writing colour:red; in your style sheets, none of your text will change color.

Make sure that when you write CSS color styles you use the US English spelling for them:

color
background-color
border-color
outline-color