The CSS border-color property allows you to set all four: top, right, bottom and left border color of a box. This property can have from one to four values as:
border-color: "can be any color how you like";
border-top-color: green;
border-right-color: red;
border-bottom-color: black;
border-left-color: orange;
Syntax : border-color: <color>{1,4}