The
line-height CSS property sets the height of a line box. It's commonly used to set the distance between lines of text. On block-level elements, it specifies the minimum height of line boxes within the element. On non-replaced inline elements, it specifies the height that is used to calculate line box height.CSS Demo: line-height
Syntax
/* Keyword value */
line-height: normal;
/* Unitless values: use this number multiplied
by the element's font size */
line-height: 3.5;
/* <length> values */
line-height: 3em;
/* <percentage> values */
line-height: 34%;
/* Global values */
line-height: inherit;
line-height: initial;
line-height: unset;
The
line-height property is specified as any one of the following:- a
<number> - a
<length> - a
<percentage> - the keyword
normal.
Values
normal- Depends on the user agent. Desktop browsers (including Firefox) use a default value of roughly
1.2, depending on the element'sfont-family. <number>(unitless)- The used value is this unitless
<number>multiplied by the element's own font size. The computed value is the same as the specified<number>. In most cases, this is the preferred way to setline-heightand avoid unexpected results due to inheritance. <length>- The specified
<length>is used in the calculation of the line box height. Values given in em units may produce unexpected results (see example below). <percentage>- Relative to the font size of the element itself. The computed value is this
<percentage>multiplied by the element's computed font size. Percentage values may produce unexpected results (see the second example below). -moz-block-height- Sets the line height to the content height of the current block.
Formal syntax
normal | <number> | <length> | <percentage>
Examples
Basic example
/* All rules below have the same resultant line height */
div { line-height: 1.2; font-size: 10pt; } /* number/unitless */
div { line-height: 1.2em; font-size: 10pt; } /* length */
div { line-height: 120%; font-size: 10pt; } /* percentage */
div { font: 10pt/1.2 Georgia,"Bitstream Charter",serif; } /* font shorthand */It is often more convenient to set
line-height by using the font shorthand as shown above, but this requires the font-family property to be specified as well.Prefer unitless numbers for line-height values
This example shows why it is better to use
<number> values instead of <length> values. We will use two <div> elements. The first, with the green border, uses a unitless line-height value. The second, with the red border, uses a line-height value defined in ems.CSS
.green {
line-height: 1.1;
border: solid limegreen;
}
.red {
line-height: 1.1em;
border: solid red;
}
h1 {
font-size: 30px;
}
.box {
width: 18em;
display: inline-block;
vertical-align: top;
font-size: 15px;
}
HTML
<div class="box green">
<h1>Avoid unexpected results by using unitless line-height.</h1>
length and percentage line-heights have poor inheritance behavior ...
</div>
<div class="box red">
<h1>Avoid unexpected results by using unitless line-height.</h1>
length and percentage line-heights have poor inheritance behavior ...
</div>
<!-- The first <h1> line-height is calculated from its own font-size (30px × 1.1) = 33px -->
<!-- The second <h1> line-height results from the red div's font-size (15px × 1.1) = 16.5px, probably not what you want -->
Result
Avoid unexpected results by using unitless line-height.
length and percentage line-heights have poor inheritance behavior ...Avoid unexpected results by using unitless line-height.
length and percentage line-heights have poor inheritance behavior ...Accessibility concerns
Use a minimum value of
1.5 for line-height for main paragraph content. This will help people experiencing low vision conditions, as well as people with cognitive concerns such as Dyslexia. If the page is zoomed to increase the text size, using a unitless value ensures that the line height will scale proportionately.Specifications
| Specification | Status | Comment |
|---|---|---|
| CSS Level 2 (Revision 1) The definition of 'line-height' in that specification. |
RECRecommendation | No change. |
| CSS Level 1 The definition of 'line-height' in that specification. |
RECRecommendation | Initial definition. |
| Initial value | normal |
|---|---|
| Applies to | all elements. It also applies to ::first-letter and ::first-line. |
| Inherited | yes |
| Percentages | refer to the font size of the element itself |
| Computed value | for percentage and length values, the absolute length, otherwise as specified |
| Animation type | either number or length |
Browser compatibility
Update compatibility data on GitHub
| 1 | 12 | 1 | 4 | 7 | 1 | 1 | 18 | 4 | 10.1 | 1 | 1.0 |
| No | No | 3.6 | No | No | No | No | No | 4 | No | No | No |
Legend
- Full support
- No support
- Non-standard. Expect poor cross-browser support.