title: drawing triangle using CSS
body: <p>I recently discovered that triangles can be created using pure css using the border property on a div with 0 width and height. Although its very simple to get this using css, I am curious on how by making border-left and border-right transparent makes a arrow up?</p>
  
  <p>As far as I know when we set the border-bottom to say 10px and make the left and right border it should become a rectangle and not a triangle with side edges transparent.</p>
  
  <p>Please explain how this works. I am sure I am wrong but curious on the clarifications.</p>