styles.css

/* styles css */
:root {
    --cherry: #532827;
    --light-cherry: #6c2726;
    --dark-cherry: #4c2827;
    --black: #000;
    --white: #ddd;
}

body {
    font-family: Georgia, 'Times New Roman', Times, serif;
    background: #333 url("assets/img/cutlery.jpg") center center no-repeat;
    background-size: cover;
    color: var(--cherry);
}

#container {
    width: 400px;
    margin: 40px auto 0px;
    padding: 50px;
    box-sizing: border-box;
    background: url("assets/img/paper-pattern.jpg") top left repeat;
    box-shadow: 0 10px 15px -8px var(--black);
    -webkit-border-radius: 5px;
    -moz-border-radius: 5px;
    border-radius: 5px;
    text-align: center;
}

h1 {
    margin: 0 0 20px;
    padding: 0 0 20px;
    border-bottom: 1px solid var(--white);
}

/* Form */
form {
    text-align: left;
}

form label {
    display: block;
    margin: 25px 0;
    font-family: bold;
    font-size: 17px;
}

form input,
form select {
    padding: 8px;
    margin: 10px 0;
}

form input[type="text"] {
    width: 90px;
}

button {
    background-color: var(--light-cherry);
    color: var(--white);
    border: none;
    border-bottom: 4px solid #222;
    text-transform: uppercase;
    font-size: 18px;
    padding: 20px 30px;
    width: 100%;
}

button:hover {
    background-color: var(--dark-cherry);
    border-bottom-color: var(--black);
}

button:active {
    position: relative;
    top: 1px;
}

/* Total tip */

#total-tip {
    font-size: 50px;
    margin-top: 40px;
}

#total-tip:before {
    content: "Tip amount";
    font-size: 14px;
    font-weight: bold;
    display: block;
    text-transform: uppercase;
}

#total-tip sup {
    font-size: 24px;
    top: -18px;
}

#total-tip small {
    font-size: 14px;
    font-weight: bold;
    display: block;
}