Tutorial Tucked Corners
<div class="corners">
Content
</div>
body {
background: #e6e6e6;
}
.corners {
background: #f6f6f6;
height: 700px;
margin: 50px auto;
max-width: 600px;
position: relative;
width: 80%;
-webkit-box-shadow: 0 1px 7px hsla(0,0%,0%,.2);
-moz-box-shadow: 0 1px 7px hsla(0,0%,0%,.2);
box-shadow: 0 1px 7px hsla(0,0%,0%,.2);
}
/* Corner Effect */
.corners:after,
.corners:before {
background: #e6e6e6;
content: '';
height: 50px;
position: absolute;
top: -25px;
width: 100px;
-webkit-box-shadow: 0 5px 10px -7px hsla(0,0%,0%,.5);
-moz-box-shadow: 0 5px 10px -7px hsla(0,0%,0%,.5);
box-shadow: 0 5px 10px -7px hsla(0,0%,0%,.5);
}
.corners:after {
left: -50px;
-webkit-transform: rotate(-45deg);
-moz-transform: rotate(-45deg);
-ms-transform: rotate(-45deg);
-o-transform: rotate(-45deg);
transform: rotate(-45deg);
}
.corners:before {
right: -50px;
-webkit-transform: rotate(45deg);
-moz-transform: rotate(45deg);
-ms-transform: rotate(45deg);
-o-transform: rotate(45deg);
transform: rotate(45deg);
}
More robust example including bottom corners at the Reference URL.