border-top-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-top-width CSS property sets the width of the top border of an element.
Try it
border-top-width: thick;
border-top-width: 2em;
border-top-width: 4px;
border-top-width: 2ex;
border-top-width: 0;
<section class="default-example" id="default-example">
<div class="transition-all" id="example-element">
This is a box with a border around it.
</div>
</section>
#example-element {
background-color: palegreen;
color: black;
border: 0 solid crimson;
padding: 0.75em;
width: 80%;
height: 100px;
}
Syntax
css
/* Keyword values */
border-top-width: thin;
border-top-width: medium;
border-top-width: thick;
/* <length> values */
border-top-width: 10em;
border-top-width: 3vmax;
border-top-width: 6px;
/* Global keywords */
border-top-width: inherit;
border-top-width: initial;
border-top-width: revert;
border-top-width: revert-layer;
border-top-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:thinmediumthick
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 value | medium |
|---|---|
| Applies to | all elements. It also applies to ::first-letter. |
| Inherited | no |
| Computed value | the absolute length or 0 if border-top-style is none or hidden |
| Animation type | a length |
Formal syntax
border-top-width =
<line-width>
<line-width> =
<length [0,∞]> |
thin |
medium |
thick
Examples
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-top-width: thick;
}
div:nth-child(2) {
border-top-width: 2em;
}
Result
Specifications
| Specification |
|---|
| CSS Backgrounds and Borders Module Level 3 # border-width |
Browser compatibility
Loading…
See also
- The other border-width-related CSS properties:
border-left-width,border-right-width,border-bottom-width, andborder-width. - The other border-top-related CSS properties:
border,border-top,border-top-style, andborder-top-color.