<div class="cp_card">
コンテンツ
  <div class="cp_ribbon09_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: 5px;
  box-shadow: 0 0 5px rgba(0, 0, 0, 0.3);
}
/*リボンの位置*/
.cp_ribbon09_2 {
  position: absolute;
  top: 15px;
  right: -6px;
}
.cp_ribbon09_2 .cp_ribbon {
  display: flex;
  align-items: center;
  height: 40px;
  padding: 0 10px 0 20px;
  color: #ffffff;
  background: #21759a;
  clip-path: polygon(0 0, 100% 0%, 100% 100%, 0 100%, 15% 50%);
}
/*リボンの影部分*/
.cp_ribbon09_2:before {
  position: absolute;
  content: '';
  top: -6px;
  right: 0;
  width: 6px;
  height: 6px;
  background: #14455b;
  clip-path: polygon(0 0, 0% 100%, 100% 100%);
}