<div class="cp_card">
コンテンツ
  <div class="cp_ribbon12_2">
    <div class="cp_ribbon">Ribbon</div>
  </div>
</div>

.cp_card {
  position: relative;/*リボンをかけたいコンテンツボックスにセット*/
  width: 300px;
  height: 300px;
  background: #ffffff;
  margin: auto;
  padding: 70px 5px 0;
  box-shadow: 0 0 5px rgba(0, 0, 0, 0.3);
}
/*リボンの設定*/
.cp_ribbon12_2 {
  position: absolute;
  top: 15px;
  left: -10px;
  width: calc(100% + 20px);
}
/*リボンの帯部分*/
.cp_ribbon12_2 .cp_ribbon {
  position: relative;
  display: flex;
  justify-content: center;
  align-items: center;
  height: 40px;
  color: #ffffff;
  background: #F48FB1;
  z-index: 0;
}
/*カットされたリボンの共通設定*/
.cp_ribbon12_2:before,
.cp_ribbon12_2:after {
  position: absolute;
  bottom: -10px;
  content: '';
  width: 40px;
  height: 40px;
  background-color: #F06292;
  clip-path: polygon(0 0, 100% 0%, 100% 100%, 0 100%, 35% 50%);
  z-index: -1;
}
.cp_ribbon12_2:before {
  left: -30px;
}
.cp_ribbon12_2:after {
  right: -30px;
  transform: scale(-1, 1);/*左右反転*/
}
/*リボンの影の共通設定*/
.cp_ribbon12_2 .cp_ribbon:before,
.cp_ribbon12_2 .cp_ribbon:after {
  position: absolute;
  top: 100%;
  content: '';
  width: 10px;
  height: 10px;
  background-color: #C2185B;
  clip-path: polygon(0 0, 100% 100%, 100% 0);
}
.cp_ribbon12_2 .cp_ribbon:before {
  left: 0;
}
.cp_ribbon12_2 .cp_ribbon:after {
  right: 0;
  transform: scale(-1, 1);/*左右反転*/
}