.box {
    width: 200px; height: 300px;
    position: relative;
    border: 1px solid #BBB;
    background: #EEE;
}
.ribbon {
    position: absolute;
    left: -5px; top: -5px;
    z-index: 1;
    overflow: hidden;
    width: 75px; height: 75px;
    text-align: right;
}
.ribbon span {
    font-size: 10px;
    font-weight: bold;
    color: #FFF;
    text-transform: uppercase;
    text-align: center;
    line-height: 20px;
    transform: rotate(-45deg);
    -webkit-transform: rotate(-45deg);
    width: 100px;
    display: block;
    background: #79A70A;
    background: linear-gradient(#F70505 0%, #8F0808 100%);
    box-shadow: 0 3px 10px -5px rgba(0, 0, 0, 1);
    position: absolute;
    top: 19px; left: -21px;
}
.ribbon span::before {
    content: "";
    position: absolute; left: 0px; top: 100%;
    z-index: -1;
    border-left: 3px solid #8F0808;
    border-right: 3px solid transparent;
    border-bottom: 3px solid transparent;
    border-top: 3px solid #8F0808;
}
.ribbon span::after {
    content: "";
    position: absolute; right: 0px; top: 100%;
    z-index: -1;
    border-left: 3px solid transparent;
    border-right: 3px solid #8F0808;
    border-bottom: 3px solid transparent;
    border-top: 3px solid #8F0808;
}