body{
    margin: 0;
    display:grid;
    justify-content: center;
    align-items: center;
    height: 100vh;
    background-color:rgb(247, 243, 243)
}
#calculator{
    font-family: Arial, Helvetica, sans-serif;
    background-color:rgb(35, 33, 33);
    border-radius: 20px;
    max-width:470px;
    overflow:hidden;
}
#display{
    width: 100%;
    padding: 03px;
    border-color:black ;
    font-size: 80px;
    text-align: center;
    border: none;
    background-color:paleturquoise;
}
#keys{
    display:grid;
grid-template-columns: repeat(4,1fr);
gap: 10px;
padding: 30px;
}
button{
    width: 90px;
    height: 50px;
    border-radius: 50px;
    border: none;
    background-color: black;
    color: white;
    font-size:30px;
    font-weight:bold ;
    cursor: pointer;
}
button:hover{
    background-color: rgb(145, 201, 53);
}
button:active{
    background-color: brown;
}
.operator-btn{
    background-color: orange;
}
.operator-btn:hover{
    background-color: rgb(244, 179, 59);
}
.operator-btn:active{
    background-color: chocolate;
}