Creating a diagonal line/section/border with CSS

Question

I am trying to create a diagonal line on a webpage, to act as a section/section break. This is essentially a split colour section. I cant use an image as if the page gets en

Answer 1

You can use CSS3 clip:

.yellow {
  width: 100%;
  height: 90px;
  background: yellow;
  -webkit-clip-path: polygon(100% 0, 0 0, 0 100%);
  clip-path: polygon(100% 0, 0 0, 0 100%);
}
.black {
  width: 100%;
  height: 90px;
  background: black;
  -webkit-clip-path: polygon(100% 0, 0 100%, 100% 99%);
  clip-path: polygon(100% 0, 0 100%, 100% 99%);
  margin-top: -90px;
}

Demo: http://jsfiddle.net/zLkrfeev/2/

It's not widely supported by the browsers: http://caniuse.com/#feat=css-clip-path