* {
    padding: 0;
    margin: 0;
    box-sizing: border-box;
}

body {
    background: url(images/calculator-1180740_1920-min.jpg);
    background-position: center;
    background-size: cover;
    color: #9f0000;
    font-size: 18px;
}

#container {
    background: #f0f0f0;
    width: 800px;
    padding: 100px;
    margin: 80px auto;
    border: 1px solid #9f0000;
}

#container h1 {
    text-align: center;
    margin-bottom: 10px;
}

#container #user-message {
    display: block;
    text-align: center;
    font-weight: bold;
    background: #ffbbbb;
    color: #333;
}

#container select,
#container label {
    display: block;
}

#container label {
    font-weight: bold;
    margin-top: 20px;
}

#calculate {
    display: block;
    background: #9f0000;
    width: 100%;
    height: 50px;
    margin-top: 20px;
    font-size: 24px;
    color: #fff;
}

#calculate:hover {
    background: #710000;
}

#total-tip:before {
    content: "Tip Amount";
    display: block;
    font-size: 25px;
    font-weight: bold;
    text-transform: uppercase;
}

#total-tip {
    display: none;
    font-size: 50px;
    text-align: center;
    margin-top: 40px;
    margin-bottom: 0;
}

#total-tip sup {
    font-size: 20px;
}