* {
  padding: 0;
  margin: 0;
  box-sizing: border-box;
}
.image-container {
  width: 30%;
  margin: 5% 0 0 5%;
}
img {
  max-width: 100%;
}
#overlay {
  display: none;
  background: url("shoe-img.jpg");
  position: absolute;
  width: 25%;
  height: 35%;
  margin-top: -30%;
  margin-left: 50%;
  border: 2px solid #555;
  z-index: 1000;
  background-repeat: no-repeat;
}
#mouse-overlay {
  cursor: zoom-in;
  position: absolute;
  width: 2em;
  height: 2em;
  transform: translate(-50%, -50%);
  background-color: rgba(245, 245, 245, 0.6);
  border-radius: 50%;
}
@media only screen and (max-width: 768px) {
  .image-container {
    width: 55%;
  }
  #overlay {
    margin-left: 70%;
    width: 25%;
    height: 15%;
  }
}