Box-Shadow
.item {
position: relative; /* or absolute */
}
.item:before {
content: "";
position: absolute;
top: 0;
left: 0;
right: 0;
bottom: 0;
background: transparent;
box-shadow: -50px 80px 4px 10px #555;
-webkit-transform: rotate(10deg);
-moz-transform: rotate(10deg);
-o-transform: rotate(10deg);
-ms-transform: rotate(10deg);
transform: rotate(10deg);
}
Xerothermic Xenomorph