Widely available
This feature is well established and works across many devices and browser versions.
Chrome
Edge
Firefox
Safari
bw-0border-width: 0;bw-1border-width: 1px;bw-2border-width: 2px;bw-3border-width: 3px;bw-4border-width: 4px;bw-5border-width: 5px;bw-6border-width: 6px;bw-7border-width: 7px;bw-8border-width: 8px;Border Block Width
byw-0border-block-width: 0;byw-1border-block-width: 1px;byw-2border-block-width: 2px;byw-3border-block-width: 3px;byw-4border-block-width: 4px;byw-5border-block-width: 5px;byw-6border-block-width: 6px;byw-7border-block-width: 7px;byw-8border-block-width: 8px;Border Bottom Width
bbw-0border-bottom-width: 0;bbw-1border-bottom-width: 1px;bbw-2border-bottom-width: 2px;bbw-3border-bottom-width: 3px;bbw-4border-bottom-width: 4px;bbw-5border-bottom-width: 5px;bbw-6border-bottom-width: 6px;bbw-7border-bottom-width: 7px;bbw-8border-bottom-width: 8px;Border Inline Width
bxw-0border-inline-width: 0;bxw-1border-inline-width: 1px;bxw-2border-inline-width: 2px;bxw-3border-inline-width: 3px;bxw-4border-inline-width: 4px;bxw-5border-inline-width: 5px;bxw-6border-inline-width: 6px;bxw-7border-inline-width: 7px;bxw-8border-inline-width: 8px;Border Left Width
blw-0border-left-width: 0;blw-1border-left-width: 1px;blw-2border-left-width: 2px;blw-3border-left-width: 3px;blw-4border-left-width: 4px;blw-5border-left-width: 5px;blw-6border-left-width: 6px;blw-7border-left-width: 7px;blw-8border-left-width: 8px;Border Right Width
brw-0border-right-width: 0;brw-1border-right-width: 1px;brw-2border-right-width: 2px;brw-3border-right-width: 3px;brw-4border-right-width: 4px;brw-5border-right-width: 5px;brw-6border-right-width: 6px;brw-7border-right-width: 7px;brw-8border-right-width: 8px;Border Top Width
btw-0border-top-width: 0;btw-1border-top-width: 1px;btw-2border-top-width: 2px;btw-3border-top-width: 3px;btw-4border-top-width: 4px;btw-5border-top-width: 5px;btw-6border-top-width: 6px;btw-7border-top-width: 7px;btw-8border-top-width: 8px;Media Queries
Prefix a class with a breakpoint to apply it from that width up.
Pseudo Classes
Prefix a class with a state to apply it only while that state matches.