body {
  overflow: hidden;
}

.bnr_fst {
  position: fixed;
  width: 100vw;
  height: 100vh;
  top: 0;
  left: 0;
  background-color: rgba(0, 0, 0, 0.5);
  z-index: 10000;
  scale: none;
  box-sizing: border-box;
}

.bnr_fst a {
  display: inline-block;
  position: absolute;
  top: 50%;
  left: 50%;
  transform: translate(-50%, -50%);
}

@media screen and (max-width: 430px) {
  .bnr_fst a {
    width: 85vw;
    height: 85vw;
  }

  .bnr_fst a img {
    max-width: 85vw;
    height: auto;
  }
}