SOURCE

<div class="star-five"></div>

.star-five {
    width: 0;
    height: 0;
    position: relative;
    border-bottom: 70px solid red;
    border-left: 100px solid transparent;
    border-right: 100px solid transparent;
    transform: rotate(35deg);
    -moz-transform: rotate(35deg); /* Firefox */
    -o-transform: rotate(35deg); /* Opera */
    -webkit-transform: rotate(35deg); /* Safari and Chrome */
    -ms-transform: rotate(35deg); /* IE 9 */
    margin-top: 80px;
	  transform: scale(0.3);
}
.star-five::before {
    content: '';
    width: 0;
    height: 0;
    display: block;
    border-bottom: 70px solid red;
    border-left: 100px solid transparent;
    border-right: 100px solid transparent;
    position: absolute;
    top: 0;
    left: -94px;
    transform: rotate(75deg);
    -moz-transform: rotate(75deg); /* Firefox */
    -o-transform: rotate(75deg); /* Opera */
    -webkit-transform: rotate(75deg); /* Safari and Chrome */
    -ms-transform: rotate(75deg); /* IE 9 */
}
.star-five::after {
    content: '';
    width: 0;
    height: 0;
    color: red;
    border-bottom: 70px solid red;
    border-left: 100px solid transparent;
    border-right: 100px solid transparent;
    transform: rotate(-70deg);
    -moz-transform: rotate(-70deg); /* Firefox */
    -o-transform: rotate(-70deg); /* Opera */
    -webkit-transform: rotate(-70deg); /* Safari and Chrome */
    -ms-transform: rotate(-70deg); /* IE 9 */
    position: absolute;
    left: -100px;
    top: 0;
}