A Pen by Jørn A. Myrland.

index.html

<div class="zigzag-edges">
  <h2>
    Hey, look at my ZigZag!
  </h2>
</div>

style.css

html, body {
    background: #8CCEE8;
}

div {
    width: 180px;
    padding: 2em;
    margin: 2em;
}

.zigzag-edges {
    position: relative;
    background: #FBFBFC; 
}

.zigzag-edges:before,
.zigzag-edges:after {
    content: ' ';
    display: block;
    height: 14px;
    position: absolute;
    left: 0;
    right: 0;

}
.zigzag-edges:before{
    top: -14px;
    
    background: 
linear-gradient(45deg, #FCFCFB 25%, transparent 25%),
linear-gradient(315deg, #FCFCFB 25%, transparent 25%),
linear-gradient(225deg, #8CCEE8 25%, transparent 25%) -7px 0,
linear-gradient(135deg, #8CCEE8 25%, transparent 25%) -7px 0;
    background-size: 14px 14px;
    background-color: #DCDCDB;
} 
.zigzag-edges:after{
    bottom: -14px;
    
    background: 
linear-gradient(135deg, #FCFCFB 25%, transparent 25%),
linear-gradient(225deg, #FCFCFB 25%, transparent 25%),
linear-gradient(315deg, #8CCEE8 25%, transparent 25%) -7px 0,
linear-gradient(45deg, #8CCEE8 25%, transparent 25%) -7px 0;
    background-size: 14px 14px;
    background-color: #DCDCDB;

}

ZigZag-edges.markdown

ZigZag edges

A Pen by Jørn A. Myrland on CodePen.

License.