A wavy underline in CSS [duplicate]

Answer 1

Without background image:

.err {
  display: inline-block;
  position: relative;
}
.err:before {
  content: "~~~~~~~~~~~~";
  font-size: 0.6em;
  font-weight: 700;
  font-family: Times New Roman, Serif;
  color: red;
  width: 100%;
  position: absolute;
  top: 12px;
  left: -1px;
  overflow: hidden;
}

A boy whose name was Peter was
  
woking
 down the street

With Background image :

.err {
    display: inline-block;
    position:relative;
    background: url(http://i.imgur.com/HlfA2is.gif) bottom repeat-x;
}

A boy whose name was Peter was 
woking
 down the street