CSS Inverse round corner

Create inverse round corners using css.

by Alain Martinez

HTML

<div id="main">
    <div class="corner"></div>
</div>

CSS

#main {
    margin: 40px;
    height: 100px;
    background-color: #004C80;
    position: relative;
    overflow: hidden;
}

#main .corner{
    position: absolute;
    width: 100%;
    height: 40px;
    border-bottom-left-radius: 20px;
    background-color: #FFF;
    left: 0; 
}