div background color not setting all area

Question

I have a div containing 3 div inside it. My problem is when am setting background color to first div, the div inside first div is not applying the background.

My code is

Answer 1

See this is the perfect answer of your query.

Css:

.how_next {
  height:auto;
  background-color:#E9E9E9;
  padding:15px;
  font-size:16px;
  font-weight:bold;
 margin-top:10px;
}
 .how_next_single {
   width:32%;
  float:left
 }

Working Link