border-left-width

Baseline Widely available

This feature is well established and works across many devices and browser versions. It’s been available across browsers since July 2015.

The border-left-width CSS property sets the width of the left border of an element.

Try it

Syntax

css
/* Keyword values */
border-left-width: thin;
border-left-width: medium;
border-left-width: thick;

/* <length> values */
border-left-width: 10em;
border-left-width: 3vmax;
border-left-width: 6px;

/* Global keywords */
border-left-width: inherit;
border-left-width: initial;
border-left-width: revert;
border-left-width: revert-layer;
border-left-width: unset;

Values

<line-width>

Defines the width of the border, either as an explicit nonnegative <length> or a keyword. If it's a keyword, it must be one of the following values:

  • thin
  • medium
  • thick

Note: Because the specification doesn't define the exact thickness denoted by each keyword, the precise result when using one of them is implementation-specific. Nevertheless, they always follow the pattern thin ≤ medium ≤ thick, and the values are constant within a single document.

Formal definition

Initial valuemedium
Applies toall elements. It also applies to ::first-letter.
Inheritedno
Computed valuethe absolute length or 0 if border-left-style is none or hidden
Animation typea length

Formal syntax

border-left-width = 
<line-width>

<line-width> =
<length [0,∞]> |
thin |
medium |
thick

Examples

Comparing border widths

HTML

html
<div>Element 1</div>
<div>Element 2</div>

CSS

css
div {
  border: 1px solid red;
  margin: 1em 0;
}

div:nth-child(1) {
  border-left-width: thick;
}
div:nth-child(2) {
  border-left-width: 2em;
}

Result

Specifications

Specification
CSS Backgrounds and Borders Module Level 3
# the-border-width

Browser compatibility

Report problems with this compatibility data on GitHub
desktopmobile
Chrome
Edge
Firefox
Opera
Safari
Chrome Android
Firefox for Android
Opera Android
Safari on iOS
Samsung Internet
WebView Android
WebView on iOS
border-left-width

Legend

Tip: you can click/tap on a cell for more information.

Full support
Full support

See also