border-bottom-width: 10em /* Any <length> value */
border-bottom-width: thin /* A keyword */
Is either a non-negative explicit <length> value or a keyword denoting the thickness of the bottom border. The keyword must be one of the following values:
A thin border
A medium border
A thick border
The specification doesn't precisely define the thickness of each of the keywords, which is therefore implementation specific. Nevertheless, it requests that the thickness does follow the thin ≤ medium ≤ thick inequality and that the values are constant on a single document.
Represents the calculated value of the border-bottom-width of the parent's element.
Thanks! Please check your inbox to confirm your subscription.
If you haven’t previously confirmed a subscription to a Mozilla-related newsletter you may have to do so. Please check your inbox or your spam filter for an email from us.
Why does MDN look different?
MDN is changing to focus just on documenting web technologies. All the same great content is still here; we’re just changing some visual elements and navigation, to help you more quickly find the web technology docs you’re looking for.
But don’t worry, MDN and Mozilla are still together! In fact, we're updating MDN’s look to reflect Mozilla's new logo and colors.