body{
    margin: 0;
    display: flex;
    justify-content: center;
    align-items: center;
    height:100vh;
    background-color: hsl(0,0%,95%);
}


#phone{
   font-family: Arial, Helvetica, sans-serif;
   background-color: hsl(0,0%,15%);
   border-radius: 15px;
   max-width:500px;
   overflow: hidden; 
}
#display{
    width:100%;
    padding:20px;
    font-size:5rem;
    text-align: center;
    border:none;
    background-color: hsl(0,0%,20%);
    color:white;
}


#keys{
    display:grid;
    grid-template-columns: repeat(3,1fr);
    gap:10px;
    padding:25px;
}

#keys-2{
    display: flex;
    flex-direction: row;
    justify-content: space-evenly;
}
button{
    width:100px;
    height:100px;
    border:none;
    background-color: hsl(0,0%,30%);
    color:white;
    font-size:3rem;
    font-weight: bold;
    cursor:pointer;
}

button:hover{
    background-color: hsl(0,0%,40%);
}

button:active{
    background-color: hsl(0,0%,50%);
}


#back{
    position: fixed;
    top:0;
    right:0;
}
#back button{
    background-color: black;
    border-radius: 50px;
}

#back a{
    font-size: medium;
    color:white;
    text-align: center;
}