100% width & height

by Naresh

HTML

<div class="wrapper">
  <div class="div1"></div>
  <div class="div2"></div>
</div>

CSS

html, body {
  height: 100%;
  padding: 0;
  margin: 0;
}

.wrapper {
  padding: 1%;
  width: 100%;
  height: 100%;
  box-sizing: border-box;
}

.div1 {
  float: left;
  width: 20%;
  background-color: red;
}

.div2 {
  float: left;
  width: 80%;
  background-color: yellow;
}

.div1, .div2 {
  height: 100%;
  
}