border-width

Summary

The border-width property sets the width of the border of a box. Using the shorthand property border is often more convenient.

Syntax

/* border-width: width */
border-width: 5px;

/* vertical | horizontal */
border-width: 2px 1.5em;

/* top | horizontal | bottom */
border-width: 1px 2em 1.5cm;

/* top | right | bottom | left */
border-width: 1px 2em 0 4rem;

border-width: inherit;

Values

<br-width>

Is either a non-negative explicit <length> value or a keyword denoting the thickness of the bottom border. The keyword must be one of the following values:

thin		A thin border
medium		A medium border
thick		A thick border

The specification doesn't precisely define the thickness of each of the keywords, which is therefore implementation specific. Nevertheless, it requests that the thickness does follow the thin ≤ medium ≤ thick inequality and that the values are constant on a single document.

inherit

Is a keyword indicating that all four values are inherited from their parent's element calculated value.

Formal syntax

<br-width>{1,4}
where 
<br-width> = <length> | thin | medium | thick

Examples

A mix of values and lengths

HTML

<p id="sval">
    one value: 6px wide border on all 4 sides</p>
<p id="bival">
    two different values: 2px wide top and bottom border, 10px wide right and left border</p>
<p id="treval">
    three different values: 0.3em top, 9px bottom, and zero width right and left</p>
<p id="fourval">
    four different values: "thin" top, "medium" right, "thick" bottom, and 1em right</p>

CSS

#sval {
    border: ridge #ccc;
    border-width: 6px;
}
#bival {
    border: solid red;
    border-width: 2px 10px;
}
#treval {
    border: dotted orange;
    border-width: 0.3em 0 9px;
}
#fourval {
    border: solid lightgreen;
    border-width: thin medium thick 1em;
}
p {
    width: auto;
    margin: 0.25em;
    padding: 0.25em;
}

Result

Specifications

Browser compatibility

See also

• The border-related shorthand properties: border, border-style, border-color
• The border-width-related properties: border-bottom-width, border-left-width, border-right-width, border-top-width