<div class="cp_card">
コンテンツ
  <div class="cp_ribbon07_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_ribbon07_2 {
  position: absolute;
  top: -6px;
  left: 15px;
}
/*リボンの設定*/
.cp_ribbon07_2 .cp_ribbon {
  position: relative;
  display: flex;
  align-items: center;
  writing-mode:vertical-rl;
  text-orientation: upright;
  width: 40px;
  padding: 10px 0px 20px;
  color: #ffffff;
  background: #FFC107;
  border-top-left-radius: 3px;
  clip-path: polygon(0% 0%, 100% 0, 100% 100%, 50% 90%, 0% 100%);
}
/*リボンの影部分*/
.cp_ribbon07_2:before {
  position: absolute;
  content: '';
  top: 0px;
  right: -6px;
  width: 6px;
  height: 6px;
  background-color: #FF8F00;
  clip-path: polygon(0 0, 0% 100%, 100% 100%);
}