<div class="cp_card">
コンテンツ
  <div class="cp_ribbon06_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_ribbon06_2 {
  position: absolute;
  top: -6px;
  right: 10px;
}
/*リボン全体の背景*/
.cp_ribbon06_2 .cp_ribbon {
  position: relative;
  display: block;
  width: 90px;
  font-size: 1em;
  line-height: 1;
  padding: 12px 0px 12px;
  text-align: center;
  color: #ffffff;
  border-top-right-radius: 8px;
  background: #4DD0E1;
  clip-path: polygon(0% 0%, 100% 0, 100% 85%, 50% 100%, 0 85%);
}
/*リボンの影の部分*/
.cp_ribbon06_2::before,
.cp_ribbon06_2::after {
  position: absolute;
  content: '';
}
.cp_ribbon06_2::before {/*リボンの影上のラウンドの部分*/
  top: 0;
  left: -5px;
  width: 5px;
  height: 5px;
  background: #4DD0E1;
}
.cp_ribbon06_2::after {/*リボンの影の半円の部分*/
  top: -5px;
  left: -10px;
  width: 10px;
  height: 10px;
  background: #00ACC1;
  clip-path: circle(50.0% at 50% 100%);
}