html,body {
  margin:0;
  padding:0;
}

.wrap {
  width: 100%;
  background-color: black;
  display: flex;
  justify-content: center;
}

.imgbox {
  width: 80%;
  height: auto;
}

img {
  width: 100%;
  height: auto;
  display: block;
  cursor: pointer;
}

@media (max-width: 768px) {
    .imgbox {
        width: 95%;
        height: auto;
    }
}