* {
  padding: 0;
  margin: 0;
  box-sizing: border-box;
}

body {
  display: flex;
  align-items: center;
  justify-content: center;
  width: 100vw;
  height: 100vh;
  background-color: steelblue;
  overflow: hidden;
}

.empty {
  height: 150px;
  width: 150px;
  border: 2px solid #000;
  margin: 30px;
  background-color: white;
}

.fill {
  background-image: url("https://picsum.photos/200/300");
  width: 146px;
  height: 146px;
  background-size: cover;
  background-position: center;
  cursor: pointer;
}

.hold {
  border: 5px solid #ccc;
}

.hovered {
  background-color: #333;
  border: 2px dotted #fff;
}

@media (max-width: 800px) {
  body {
    flex-direction: column;
    overflow-y: scroll;
    height: auto;
  }

  .empty {
    margin: 10px;
  }
}