What this Bootstrap Utility API class does
Sets the border-width property of an element.
The CSS property border-width is used to set the width of the border on an element. It can be used to set the width of all four borders (top, right, bottom, and left) at once, or to set the width of individual borders using the border-top-width, border-right-width, border-bottom-width, and border-left-width properties.
The CSS value of border-width can be specified using a length unit such as pixels, ems, or percentages, or using one of the following keywords: thin, medium, or thick. By default, the value of border-width is medium, which is typically rendered as a 2-pixel wide border.
Example usage & available classes
<span class="border border-1"></span> <span class="border border-2"></span> <span class="border border-3"></span> <span class="border border-4"></span> <span class="border border-5"></span>
In the example below, we are making the utility responsive, which means you can also use it per breakpoint: ".border-lg-3"
"border-width": map-merge( map-get($utilities, "border-width"), ( responsive: true ) )