* {
  background: #e1e1e1;
}

<svg class="decor" height="100%" preserveaspectratio="none" version="1.1" viewbox="0 0 100 100" width="100%" xmlns="http://www.w3.org/2000/svg">
  <path d="M0 0 L100 100 L0 100" stroke-width="0"></path>
</svg>