The border-width shorthand CSS property sets the width of an element's border.
/* 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;This property is a shorthand for the following CSS properties: