<div class="cp_card">
コンテンツ
  <div class="cp_ribbon07">
    <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 {
  position: absolute;
  top: -6px;
  left: 15px;
  text-align: center;
  writing-mode:vertical-rl;
  text-orientation: upright;
  border-top-left-radius: 3px;
  color: #ffffff;
  background: #FFC107;
}
/*リボン内のテキスト*/
.cp_ribbon07 .cp_ribbon {
  position: relative;
  display: flex;
  align-items: center;
  width: 40px;
  padding: 10px 0px;
}
/*擬似要素の共通設定*/
.cp_ribbon07:before,
.cp_ribbon07:after {
  position: absolute;
  content: '';
}
.cp_ribbon07:before {/*リボンの影部分*/
  top: 0.1px;
  right: -5.5px;
  border-right: 6px solid transparent;
  border-bottom: 6px solid #FF8F00;
}
.cp_ribbon07:after {/*リボン下のカット部分*/
  bottom: -19.5px;
  left: 0;
  border-right: 20px solid #FFC107;
  border-bottom: 20px solid transparent;
  border-left: 20px solid #FFC107;
}