Google’s CSS Style Guides

Stylesheet guidelines are dominated by further best-practice and byte-saving techniques:

  • use valid CSS unless dealing with bugs or proprietary syntaxes (vendor prefixes)
  • use short ID and class names, but ensure they’re not cryptic or presentational (e.g. #blue-button)
  • consider prefixed names for larger projects, e.g. #xyz-help, .xyz-column
  • simplify selectors when possible, e.g. #example rather than ul#example
  • use shorthand syntax notations
  • do not use quotes in url() or unit values after a zero
  • use short #abc hexadecimal color notation rather than #aabbcc
  • end every declaration with a semi-colon (even the last one)
  • avoid browser hacks

Google suggests omitting leading zeros from measurements, such as .5em. It saves a character!

The guide recommends a newline for every comma-separated selector which applies to a block.

Finally, it states that property declarations should be alphabetized, e.g.
border: 1px solid #000;
border-radius: 6px;
display: block;
font-family: sans-serif;
margin: 1em;
outline: 0;
padding: 10px;
text-align: center;

Read the complete set of guidelines!