1. If you apply a style to multiple selectors, separate the selectors with a comma and a line-break.

2. The opening curly brace is divided by a space from the selector and a line-break for the statements.

3. Every CSS command is indented with a tab, every property is followed by a colon and then a white-space, every statement is separated by a line-break.

4. When using the short version for properties like “padding”, “margin” or “border”, instead of “padding-left”, “padding-right”…, all four values are preferred (padding: 10px 0 10px 0). Two values are also allowed in this case (padding: 10px 0).

5. Null-values should be abbreviated with “0” instead of “0em” or “0px”.