Colors in JavaScript Console

In Chrome & Firefox (+31) you can add CSS in console.log messages:

console.log('%cHello, world!', 'background: red; color: green')

The same can be applied for adding multiple CSS to a command:

console.log('%c<str1> %c<str2>', '<css-for-str1>', '<css-for-str2>')

Chrome Console API Reference: Console API Reference.