div {
  background-color: #bada55;
  width: 475px;
  float: left;
  margin-left: 30px;
  height: 100%;
}
html,
body {
  height: 100%;
  min-height: 100%;
}
<div>
</div>
I have a div I want to extend to bottom of screen. I'm not sure why but this is not working for me:
div {
    background-color: #bada55;
    width: 475px;
    float: left;
    margin-left: 30px;
    height: 100%;
} 
html, body {
    height: 100%;
    min-height: 100%;
}