±ß¿ò¿í¶È | border-width

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

/* <length> values */border-width: 4px;
border-width: 1.2rem;
/* 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;

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

Applies to all elements. It also applies to [`::first-letter`](::first-letter).   [Inherited](inheritance) no   Media visual   [Computed value](computed_value) as each of the properties of the shorthand:

Animation type as each of the properties of the shorthand:

Canonical order the unique non-ambiguous order defined by the formal grammar  

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

<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;
}