13.Totally-Triangle.html

<div></div>
<style>
  body {
margin:0;
background:#0B2429;

}
  div {
    position:absolute;
    left:-100;
    top:-100;
    transform: rotateZ(-45deg);
    width: 200px;
    height: 200px;
    background: #F3AC3C;
  }
</style>