The border-width shorthand CSS property sets the width of an element's border.
- <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:
- thin
- medium
- thick
border-width="0.3em 0 9px"
border-width="thin medium thick 1em"
border-width="2px 10px"
border-width="6px"