Like border-style, but for the bottom border only.
default
border-bottom-style: none;
Removes the bottom border.
border-bottom-style: dotted;
Turns the bottom border into a sequence of dots.
border-bottom-style: dashed;
Turns the bottom border into a sequence of dashes.
border-bottom-style: solid;
Turns the bottom border into a solid line.
border-bottom-style: double;
Splits the bottom border into two lines.
border-bottom-style: groove;
Sets an inset style to the bottom border.