CSS <number> Data Type

The CSS <number> data type represents real numbers, possibly with a fractional component.

A valid <number> can include fractions, and it can also be immediately preceded by - (negative sign) or + (positive sign) to indicate a negative or positive value respectively. A <number> can also have an exponent composed of "e" or "E" and an integer.

So the following are all valid <number> values:

Example

When you see <number> (including the < and >) anywhere in the CSS specifications, this refers to the fact that the value can be any valid number.

For example, the official syntax for the cubic-bezier() function looks like this:

Which means that you must pass four arguments of type <number> to the function whenever you use it.

So you could do something like this:

Which will result in this:

Official Definition

The official definition for the <number> type goes like this:

Number values are denoted by <number>, and represent real numbers, possibly with a fractional component.

When written literally, a number is either an integer, or zero or more decimal digits followed by a dot (.) followed by one or more decimal digits and optionally an exponent composed of "e" or "E" and an integer. It corresponds to the <number-token> production in the CSS Syntax Module [CSS3SYN]. As with integers, the first character of a number may be immediately preceded by - or + to indicate the number's sign.

CSS Specifications