The <integer> data type consists of one or several decimal digits, 0 through 9 inclusive, optionally preceded by a single + or - sign. There is no unit associated with integers.
Note: There is no official range of valid <integer> values. Opera 12.1 supports values up to 2^15 - 1, IE up to 2^20 - 1, and other browsers even higher. During the CSS3 Values cycle there was a lot of discussion about setting a minimum range to support: the latest decision, in April 2012 during the LC phase, was [-2^27 - 1; 2^27 - 1], but other values like 2^24 - 1 and 2^30 - 1 were also proposed. However, the latest spec doesn't specify a range anymore.