How to make double lines border in CSS, each line in different color, without using background image?

Question

How to make a double line border in CSS, each line in a different color without using background-image?

For example like this:

Answer 1

Just had to do this, we're implementing a two-tone shadow in our app. Being an mobile app we want to avoid box-shadow (performance) so an even simpler solution using :after, where its absolutely positioned based on its parent is:

 :after{
   content: '';
   display: block;
   height:0;
   border-top: 1px solid rgba(0, 0, 0, .1);
   border-bottom: 2px solid rgba(0, 0, 0, .05);
   position: absolute;
   bottom: -3px;
   left: 0;
   width: 100%;
 }