html, body {
  height: 100%;
  margin: 0;
}

body {
  display: flex;
  flex-direction: column;
}

.main-img {
  width: 400px;
  height: 400px;
  object-fit: cover;
}

@media(max-width: 768px){
  .main-img {
    width: 250px;
    height: 250px;
    object-fit: cover;
  }
}