body {
  overflow: hidden;
  margin: 0;
}


container {
    width: 100%;
    height: 100%;
    padding: 0;
    box-sizing: border-box;
    
    text-align: center;
}
div{
  position: absolute;
  top: 50%;
  left: 50%;
  background: tomato;
  height: 100vh;
  max-height: 100vw;
  width: 100vw;
  max-width: 100vh;
  transform: translate(-50%, -50%);
}
#boxdiv {
   
   width: 100vmin;
   height: 100vmin;
   margin: 0 auto;
}