CSS - border-width

Example

<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>

#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;
}

Syntax  

/* border-width: width */ /* the width applies to all sides */
border-width: 5px;

/*border-width: top&bottom right&left */
border-width: 2px 1.5em;

/* border-width: top right&left bottom */
border-width: 1px 2em 1.5cm;

/* border-width: 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 border area of a box. 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

<a href="css/border-width#br-width"><br-width></a><a href="css/value_definition_syntax#curly_braces_(.7b_.7d)" title="Curly braces">{</a>1,4<a href="css/value_definition_syntax#curly_braces_(.7b_.7d)" title="Curly braces">}</a><p>where <br><code><br-width> = <a href="css/length" title="Possible values: a number followed by'em', 'ex', 'ch', 'rem', 'px', 'cm', 'mm', 'in', 'vh', 'vw', 'vmin', 'vmax', 'pt', 'pc' or 'px', like 3px, 1.5cm, -0.5em or 0"><length></a> <a href="css/value_definition_syntax#single_bar" title="Single bar">|</a> thin <a href="css/value_definition_syntax#single_bar" title="Single bar">|</a> medium <a href="css/value_definition_syntax#single_bar" title="Single bar">|</a> thick</code></p>

Description  

The border-width property is a shorthand property for setting border-top-width, border-right-width, border-bottom-width and border-left-width of a box at the same place.

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

Specifications  

License