.wp-block-image.is-style-chatterton{
    position: relative;
}
.wp-block-image.is-style-chatterton::after{
    content: '';
    position: absolute;
    top: -10px;
    left: -30px;
    width: 65px;
    height: 25px;
    background: #FFF;
    z-index: 5;
    transform: rotate(-45deg);
}
.wp-block-image.is-style-chatterton::before{
    content: '';
    position: absolute;
    bottom: -10px;
    right: -20px;
    width: 60px;
    height: 25px;
    background: #FFF;
    z-index: 5;
    transform: rotate(-45deg) skew(0deg, 10deg);
}