Edit in JSFiddle

<div class="box">
  <details open>
    <summary>
      第一种 原形镂空
    </summary>
    <div class="c-style-1"></div>
  </details>


  <details open>
    <summary>
      第二种 连续镂空
    </summary>
    <div class="c-style-1 c-style-2"></div>
  </details>

  <details>
    <summary>
      原图
    </summary>
    <img src="http://img95.699pic.com/element/40118/4001.png_860.png" alt="">
  </details>

  <details open>
    <summary>
      实现
    </summary>
    <div class="coupons-wrap lacework">
      <div class="coupons-name">
        <span>20元</span>
        <p>优惠券</p>
      </div>
      <p class="coupons-line"></p>
      <div class="coupons-info">
        <p class="coupons-info-name">优惠券减 20</p>
        <p style="font-size: 20px;">满 50 元可用</p>
      </div>
    </div>
  </details>
</div>

  * {
    margin: 0;
    padding:0;
  }
  img {
    width: 400px;
    height: 400px;
    display: block;
    margin: 50px auto;
  }

  .box {
    margin: 100px auto;
  }

  .box div { margin: auto }

  details {
    text-indent: 20px;
    margin: 20px  0;
  }

  summary {
    outline: none;
  }

  .c-style-1 {
    position: relative;
    width: 300px;
    height: 150px;
    margin-top: 20px;
    background: radial-gradient(circle at top right, transparent 13px, #f26f4c 0) left top / 51% 50% no-repeat,
    radial-gradient(circle at bottom right, transparent 13px, #f26f4c 0) left bottom / 51% 50% no-repeat,
    radial-gradient(circle at left top, transparent 13px, #f26f4c 0) right top / 51% 50% no-repeat,
    radial-gradient(circle at left bottom, transparent 13px, #f26f4c 0) right bottom / 51% 50% no-repeat;
    filter: drop-shadow(2px 2px 2px rgba(0,0,0,.2));
    /*background-origin: content-box;*/
  }

  .c-style-2:after {
    content: "";
    position: absolute;
    top: 0;
    bottom: 0;
    right: -11px;
    width: 11px;
    /*background-color: #5cb85c;*/
    background-image: linear-gradient(to bottom, #f26f4c 0px, transparent 5px, transparent),
    radial-gradient(circle at 10px, transparent 5px, #f26f4c 5px);
    background-repeat: repeat;
    background-size: 11px 15px;
  }

.coupons-wrap {
    text-indent: 0;
    margin: auto;
    display: flex;
    justify-content: space-between;
    /*764 40%*/
    width: 305px; /*减去两边的花边 17px（未换算）*/
    height: 132px;
    padding-top: 6px;
    padding-left: 6px;
    position: relative;
    background: radial-gradient(circle at top right, transparent 11px, #f26f4c 0) left top / 99px 66px  no-repeat,
    radial-gradient(circle at right bottom, transparent 11px, #f26f4c 0) left bottom / 99px 66px no-repeat,
    radial-gradient(circle at left top, transparent 11px, #f26f4c 0) right top / 206px 66px no-repeat,
    radial-gradient(circle at left bottom, transparent 11px, #f26f4c 0) right bottom / 206px 66px no-repeat;
    -webkit-font-smoothing: antialiased;
    filter: drop-shadow(2px 2px 2px rgba(0,0,0,.2));
    box-sizing: border-box;
  }
  .coupons-wrap > div { margin: 0 }

  .lacework:before {
    content: '';
    position: absolute;
    height: 100%;
    width: 7px;
    top: 0;
    left: -7px;
    /* #f26f4c 5px: 第一段有颜色的距离，transparent 7px：圆的半径 */
    background-image: linear-gradient(to bottom, #f26f4c 5px, transparent 7px, transparent),
      /*6px 半径，1px, 12 前面颜色的距离加上半径的距离 6px 后面的半径距离*/
    radial-gradient(6px circle at 1px 12px, transparent 6px, #f26f4c 6px);
    /*一段距离的长度*/
    background-size: 7px 18px;
  }

  .lacework:after {
    content: '';
    position: absolute;
    height: 100%;
    width: 7px;
    top: 0;
    right: -7px;
    /* #f26f4c 5px: 第一段有颜色的距离，transparent 7px：圆的半径 */
    background-image: linear-gradient(to bottom, #f26f4c 5px, transparent 7px, transparent),
      /*6px 半径，6px: 需要突出来的距离 12 前面颜色的距离加上半径的距离 6px 后面的半径距离*/
    radial-gradient(6px circle at 6px 12px, transparent 6px, #f26f4c 6px);
    /*一段距离的长度*/
    background-size: 7px 18px;
  }

  .coupons-name {
    width: 65px;
    height: 118px;
    position: relative;
    font-size: 20px;
    background-color: #ffffff;
    box-sizing: border-box;
    color: #f26f4c;
    display: flex;
    flex-direction: column;
    justify-content: center;
  }

  .coupons-name > span {
    width: 100%;
    text-align: center;
    margin-bottom: 9px;
  }

  .coupons-name > p {
    /*垂直方向 自左而右方向书写*/
    margin-block-start: 1em;
    margin-block-end: 1em;
    /*margin-inline-start: 0px;*/
    /*margin-inline-end: 0px;*/
    writing-mode: vertical-rl;
  }

  .coupons-name:after {
    content: '';
    position: absolute;
    height: 100%;
    right: -7px;
    width: 7px;
    top: 0;
    /* #f26f4c 5px: 第一段有颜色的距离，transparent 7px：圆的半径 */
    background-image: linear-gradient(to bottom, #ffffff -4px, transparent -5px, transparent), /*6px 半径，6px: 需要突出来的距离 12 前面颜色的距离加上半径的距离 6px 后面的半径距离*/ radial-gradient(13px circle at 7px 8px, transparent 5px, #ffffff 6px);
    background-size: 11px 17px;
  }

  .coupons-line {
    position: absolute;
    height: calc(100% - 22px);
    border: 1px dashed #fff;
    top: 11px;
    left: 98px;
  }

  .coupons-info {
    width: 192px;
  }

  .coupons-info > p {
    text-align: center;
    color: #fff;
  }

  .coupons-info-name {
    line-height: 82px;
    font-size: 30px;
  }