body * {
    box-sizing: border-box;
}

body {
    background-color: antiquewhite;
    display: flex;
    justify-content: center;
    align-items: center;
    height: 100vh;
    font-family: Arial, Helvetica, sans-serif;
    flex-direction: column;
}

#calculator {
    border-radius: 10px;
    overflow: hidden;
    box-shadow: 0 0 20px rgba(0,0,0,0.3);
}

#display {
    min-width: 300px;
    font-size: 30px;
    line-height: 50px;
    text-align: right;
    padding: 0 10px;
    background-color: #000000;
    color: #fff;
}

#buttons {
    display: grid;
    grid-template-columns: repeat(4, 1fr);
}

button.double {
    grid-column: span 2;
}

button.operator {
    background-color: coral;
}

button.equal {
    background-color: rgb(8, 134, 151);
}

button.cancel {
    background-color: rgb(255, 5, 5);
}

button {
    border: none;
    height: 50px;
    font-size: 20px;
    /* border: 1px solid #ccc; */
}

button:hover {
    background-color: #999;
    cursor: pointer;
}