#container {
  position: absolute;
  top: 0;
  left: 0;
  width: 100vw;
  height: 100vh;
  margin: 0;
  display: flex;
  justify-content: center;
  align-items: center;
}
#content {
  width: 800px;
  height: 900px;
  border: 5px solid blue;
}
#content {
  width: 500px;
  height: 500px;
  border: 5px solid blue;
  border-radius: 50%;
}
#content {
  width: 500px;
  height: 500px;
  border: 5px solid blue;
  border-radius: 50%;
  overflow: hidden;
}
#content {
  width: 500px;
  height: 500px;
  border: 5px solid blue;
  border-radius: 0%;
  overflow: hidden;
  background-image: 
  background-repeat: no-repeat;
  background-position: center top;
  background-size: cover;