the demo: Jsfiddle here
Code
figure {
position: relative;
width: 200px;
height: 120px;
margin: 100px auto;
overflow: hidden;
border: 1px solid black;
border-right: none;
border-bottom: none;
border-bottom-left-radius: 5px;
border-top-left-radius: 5px;
}
figure:before,
figure:after {
content: '';
position: absolute;
}
figure:before {
right: -50%;
top: 0;
background: transparent;
width: 172px;
height: 200px;
border: 1px solid black;
border-radius: 100%;
box-shadow: 0 0 0 100em red;
}
figure:after {
left: -1px;
bottom: 0px;
height: 16px;
width: 128px;
border-top-left-radius: 0;
border-bottom-left-radius: 5px;
border-left: 1px solid black;
border-bottom: 1px solid black;
}
<figure></figure>