*{
    margin:0;
    padding:0;
    box-sizing:border-box;
    font-family:Arial, sans-serif;
}

body{
    background:#1e1e1e;
    display:flex;
    justify-content:center;
    align-items:center;
    height:100vh;
}

.calculator{
    background:#2d2d2d;
    padding:20px;
    border-radius:15px;
    width:330px;
    box-shadow:0 0 20px rgba(0,0,0,.4);
}

#display{
    width:100%;
    height:60px;
    border:none;
    outline:none;
    font-size:28px;
    text-align:right;
    padding:10px;
    border-radius:10px;
    margin-bottom:15px;
}

.buttons{
    display:grid;
    grid-template-columns:repeat(4,1fr);
    gap:10px;
}

button{
    padding:18px;
    font-size:20px;
    border:none;
    border-radius:10px;
    cursor:pointer;
    background:#444;
    color:white;
    transition:.2s;
}

button:hover{
    background:#666;
}

.clear{
    background:#e63946;
}

.clear:hover{
    background:#ff4d5a;
}

button:last-child{
    background:#2a9d8f;
}

button:last-child:hover{
    background:#38b2a3;
}