body {
    background-color: #e6f2ff; /* 柔らかい水色 */
    margin: 0;
    font-family: "Segoe UI", Arial, sans-serif;
    display: flex;
    justify-content: center;
    align-items: center;
    min-height: 100vh; /* 画面中央に配置 */
    text-align: center;
}

.container {
    max-width: 600px;
    padding: 20px;
    background: white;
    border-radius: 12px;
    box-shadow: 0 4px 12px rgba(0,0,0,0.15);
}

h1 {
    font-size: 2.2em;
    margin-bottom: 0.5em;
    color: #003366;
}

h2 {
    font-size: 1.4em;
    margin-bottom: 1em;
    color: #005599;
}

p {
    font-size: 1.1em;
    margin-bottom: 1.5em;
}

em {
    color: red;
    font-weight: bold;
}

a.btn {
    padding: 12px 24px;
    font-size: 1.2em;
    color: white;
    background-color: #007acc;
    border-radius: 8px;
    text-decoration: none;
    transition: background-color 0.3s ease;
}

a.btn:hover {
    background-color: #005fa3;
}

/* スマホ対応 */
@media (max-width: 600px) {
    body {
        padding: 10px;
    }
    .container {
        padding: 15px;
    }
    h1 {
        font-size: 1.8em;
    }
    h2 {
        font-size: 1.2em;
    }
    p {
        font-size: 1em;
    }
    a.btn {
        font-size: 1.1em;
        width: 100%;
    }
}