Rounded Hexagon [Modified] - source: http://css-tricks.com/snippets/css/hexagon-with-shadow/

hexagon.css

.hexagon {
    width: 120px;
    height: 60px;
    position: relative;
}
.hexagon, .hexagon:before, .hexagon:after {
    background: red;
    border-radius: 5px  
}
.hexagon:before, .hexagon:after {
    content: "";
    position: absolute;
    left: 23px;
    width: 74px;
    height: 70px;
    -moz-transform: rotate(145deg) skew(22.5deg);
    -webkit-transform: rotate(145deg) skew(22.5deg);
    transform: rotate(145deg) skew(22.5deg);
}
.hexagon:before {
    top: -35px;
}
.hexagon:after {
    top: 35px;
}
.hexagon span {
    position: absolute;
    top: 0;
    left: 0;
    width: 120px;
    height: 70px;
    background:red;
    z-index: 1;
}

body { padding: 100px; }

index.html

<div class="hexagon"><span></span></div>