html,body{
    height: 100%;
}
#container{
    width : 100%;
    height: 100%;
/*    border:3px solid red;*/
    display: flex;
    flex-direction: column;
    justify-content: center;
    align-items: center;
}
#box{
/*    border:3px solid green;*/
    width:50%;
    height:60%;
    display: flex;
    flex-direction: column;
    justify-content: center;
}
#box div{
/*    border:3px solid blue;*/
    height: 20%;
/*
    min-height: 300px;
    min-width: 300px;
*/
    display: flex;
    justify-content: center;
    align-items: center;
    font-size: 30px;
}
.red{
    color:red;
}