main ul li:not(:last-child) {
  margin-bottom: 2rem;
}
main ul li a {
  display: flex;
  flex-direction: column;
  padding: 2rem;
  border: 1px solid #ddd;
  border-radius: 1.2rem;
  height: 12rem;
  box-shadow: rgba(0, 0, 0, 0.15) 1.95px 1.95px 2.6px;
  position: relative;
  overflow: hidden;
}
main ul li a::after {
  content: "";
  width: 100%;
  height: 100%;
  position: absolute;
  top: 0;
  left: 0;
  background: rgba(0, 0, 0, 0.5);
}
main ul li a h2 {
  font-size: 2.4rem;
  font-weight: 600;
  margin-top: auto;
  z-index: 9;
  color: #fff;
  letter-spacing: -.05rem;
}

main ul li:nth-child(1) a {
  background: url("../img/sub1.jpg") no-repeat center / cover;
}
main ul li:nth-child(2) a {
  background: url("../img/sub2.jpg") no-repeat center / cover;
}
main ul li:nth-child(3) a {
  background: url("../img/sub3.jpg") no-repeat center / cover;
}
main ul li:nth-child(4) a {
  background: url("../img/sub4.jpg") no-repeat center / cover;
}
main ul li:nth-child(5) a {
  background: url("../img/sub5.jpg") no-repeat center / cover;
}
main ul li:nth-child(6) a {
  background: url("../img/sub6.jpg") no-repeat center / cover;
}