# rem

The rem CSS function contains two calculations A and B, and returns the difference between A and the nearest integer multiple of B either above or below A.

If the A value and the B step are on opposite sides of zero: rem() (short for "remainder") chooses the integer multiple of B that puts the value between zero and -B.

## Syntax

`rem()`

### Values

```<rem()> =
rem(
<calc-sum>,
<calc-sum>
)```
```<calc-sum> =
<calc-product>
[ [ '+' | '-' ] <calc-product> ]*```
```<calc-product> =
<calc-value>
[ [ '*' | '/' ] <calc-value> ]*```
```<calc-value> =
<number> |
<dimension> |
<percentage> |
<calc-constant> |
( <calc-sum> )```
`<number>`

An integer or zero or more decimal digits followed by a dot (.) followed by one or more decimal digits. The first character may be preceded by a sign (- or +). The last character may be succeeded by an exponent (e or E) and an integer.

`<dimension>`

A number with a unit.

`<percentage>`

Specifies the percentage using a number followed by a percent sign (%).

```<calc-constant> =
e |
pi |
infinity |
-infinity |
NaN```
`e`

The base of the natural logarithm, approximately equal to 2.7182818284590452354.

`pi`

The ratio of a circle's circumference to its diameter, approximately equal to 3.1415926535897932.

`infinity`

Positive infinity.

`-infinity`

Negative infinity.

`NaN`

Not a number.

`*`

Multiplication.

`/`

Division.

`+`

`-`

Subtraction.