* {
    box-sizing: border-box;
}

body {
    margin: 0;
    font-family: Arial, Helvetica, sans-serif;
    background: #f4f4f4;
    color: #222;
    line-height: 1.6;
}

.shell {
    width: 100%;
    max-width: 900px;
    margin: 0 auto;
    padding: 40px 20px;
}

.card {
    background: white;
    border-radius: 12px;
    padding: 40px;
    box-shadow: 0 4px 18px rgba(0, 0, 0, 0.08);
}

h1 {
    margin-top: 0;
    font-size: 32px;
}

h2 {
    margin-top: 30px;
}

.intro {
    font-size: 18px;
    color: #555;
    margin-bottom: 30px;
}

button {
    background: #111;
    color: white;
    border: none;
    border-radius: 6px;
    padding: 12px 20px;
    font-size: 16px;
    cursor: pointer;
    margin-top: 15px;
}

button:hover {
    background: #333;
}

input,
select,
textarea {
    width: 100%;
    padding: 12px;
    margin: 8px 0 18px;
    border: 1px solid #bbb;
    border-radius: 6px;
    font-size: 16px;
}

label {
    font-weight: bold;
    display: block;
    margin-top: 12px;
}

.option {
    padding: 15px;
    margin: 10px 0;
    border: 1px solid #ddd;
    border-radius: 8px;
    background: #fafafa;
}

.notice {
    background: #f1f1f1;
    padding: 15px;
    border-radius: 8px;
    margin: 20px 0;
}

@media (max-width: 600px) {
    .shell {
        padding: 15px;
    }

    .card {
        padding: 24px;
    }

    h1 {
        font-size: 26px;
    }
}