body{
    display:flex;
    justify-content:center;
    align-items:center;
    min-height:100vh;
    margin:0;
    
}
.navbar{
    background-color:grey;
    position:absolute;
    top:0;
    left:0;
    width:100%;
    display:flex;
    align-items:center;
    justify-content:space-evenly;
    font-family:helvetica;
    
}
.navbar a{
    color:aqua;
    text-decoration:none;
}
.container{
    background-color:hsl(0, 0%, 80%);;
    max-width:450px;
    border-radius:5px;    
}
#display{
    width:100%;
    height:100px;
    background-color:grey;
    overflow:hidden;
    font-size:2rem;
    border:none;
    box-sizing:border-box;
    border-radius:5px;
    color:white;
    text-align:left;
}
.operator{
    background-color: hsl(34, 78%, 51%);
}
.operator:hover{
    background-color: hsl(34, 78%, 70%);
}
.operator:active{
    background-color: hsl(34, 78%, 90%);
}
.keys{
    display:grid;
    grid-template-columns: repeat(4,1fr);
    gap:10px;
    padding:10px;
    
}
button{
    width:100px;
    height:50px;
    border-radius:50px;
    font-size:2em;
    font-weight:bold;
    background-color: hsl(191, 5%, 39%);
    color:white;
    border:none;
    font-family:monospace;
}
button:hover{
    cursor:pointer;
    background-color:hsl(191, 5%, 43%);
}
button:active{
    background-color: hsl(191, 5%, 60%);
}
@media(max-width:768px){
    body{
        display:flex;
        justify-content:center;
        align-items:center;
    }
    .container{
        width:250px;
        height:450px;
        margin:0;
    }
    .keys{
        display:grid;
        grid-template-columns:repeat(4,1fr);
    }
    button{
        width:100%;
        height:100%;
        padding:10px;

    }
    .navbar{
        font-size:small;
    }


}