Solid is a border that consists of a single line segment. Double is a border made up of two solid lines. The value of the border-width of a double border consists of the two lines and the space between them. Dashed is a border made up of a series of line segments. Dotted is a border made up of a series of dots.
Groove is a border that looks like it has been carved into the background.
Ridge is the opposite of groove. This border looks as if it's protruding out of the background, like a speed bump. Inset is a border that makes its box look like it is embedded in the background. Outset is a border that makes its box look like it is protruding out of the background. You can enter one to four values to set different styles for different sides of the border.