.shape-ex4{
    width: 200px;
    height: 110px;
    background-color: #666;
    display: block;
    position: relative;
    margin-top: 90px;
}
.shape-ex4::after{
    content: '';
    width: 0;
    height: 0;
    display: block;
    border-left: 100px solid transparent;
    border-bottom: 90px solid #666;
    border-right: 100px solid transparent;
    position: absolute;
    bottom: 100%;
    left: 0;
}