<div class="qr-scanner">
  <div class="box">
    <div class="line"></div>
    <div class="angle"></div>
  </div>
</div>

body {
  display: flex;
  align-items: center;
  justify-content: center;
  height: 100vh;
  margin: 0;
}

.qr-scanner {
   position: relative;
   height: 200px; width: 200px;
   background: url(https://mankeung.github.io/docs/mk-data/w.jpg);
   background-repeat: no-repeat;
   background-size: 200px 200px;
   background-position: center;
}

.qr-scanner .box {
  width: 220px;
  height: 220px;
  max-height: 220px;
  max-width: 220px;
  position: relative;
  left: 50%;
  top: 50%;
  transform: translate(-50%, -50%);
  overflow: hidden;
  border: 0.1rem solid rgba(0, 255, 51, 0.2);
}

.qr-scanner .line {
  height: calc(100% - 2px);
  width: 100%;
  background: linear-gradient(180deg, rgba(0, 255, 51, 0) 43%, #00ff33 211%);
  border-bottom: 3px solid #00ff33;
  transform: translateY(-100%);
  animation: radar-beam 2s infinite;
  animation-timing-function: cubic-bezier(0.53, 0, 0.43, 0.99);
  animation-delay: 1.4s;
}

.qr-scanner .box:after,
.qr-scanner .box:before,
.qr-scanner .angle:after,
.qr-scanner .angle:before {
  content: '';
  display: block;
  position: absolute;
  width: 3vw;
  height: 3vw;

  border: 0.2rem solid transparent;
}

.qr-scanner .box:after,
.qr-scanner .box:before {
  top: 0;
  border-top-color: #00ff33;
}

.qr-scanner .angle:after,
.qr-scanner .angle:before {
  bottom: 0;
  border-bottom-color: #00ff33;
}

.qr-scanner .box:before,
.qr-scanner .angle:before {
  left: 0;
  border-left-color: #00ff33;
}

.qr-scanner .box:after,
.qr-scanner .angle:after {
  right: 0;
  border-right-color: #00ff33;
}

@keyframes radar-beam {
  0% {
    transform: translateY(-100%);
  }

  100% {
    transform: translateY(0);
  }
}