border-bottom

The border-bottom property is a shorthand property for setting the width, style, and color of the bottom border of a box.

Description

Values	[ <border-bottom-width> \|\| <border-bottom-style> \|\| <border-bottom-color> ] \| inherit
Initial value	See individual properties
Applies to	all elements
Inherited	No

inherit
Takes the same specified value as the property for the element's parent.

And see also individual properties

[style.css]

 h1 {
   border-bottom: 1px solid red;
 }

[index.html]

  <body>
    <h1>CSS border property example</h1>
  </body>

The CSS specification defines the border-bottom property in 8.5.4 Border shorthand properties.