body {
    font-family: "Zen Maru Gothic", sans-serif;
    font-weight: 700;
    background-color: #ffffff;
    margin: 0;
    color: #963403;
}

header {
    text-align: center;
    padding: 30px;
}

header h1 { margin: 10px 0 0; }

#title {
    text-decoration: none;
    color: #963403;
}

.back-link {
    text-decoration: none;
    color: #963403;
    font-size: 0.9rem;
    opacity: 0.6;
}

#viewer { width: 100%; }

/* --- アップル風：ふわっとアニメーション --- */
.fade-in {
    opacity: 0;
    transform: translateY(40px);
    transition: opacity 1.4s cubic-bezier(0.25, 1, 0.5, 1), 
                transform 1.4s cubic-bezier(0.25, 1, 0.5, 1);
    will-change: opacity, transform;
}

.fade-in.is-visible {
    opacity: 1;
    transform: translateY(0);
}
/* ---------------------------------- */

/* 表紙：最大800pxで中央寄せ */
.cover-section {
    width: 100%;
    max-width: 800px;
    margin: 0 auto 80px;
    text-align: center;
}

.cover-section .ehon-image {
    width: 100%;
    height: auto;
    border-radius: 0;
    display: block;
}

/* 本編ページ：最大600pxで中央寄せ */
.page-section {
    max-width: 600px;
    margin: 80px auto;
    padding: 0 20px;
    text-align: center;
    box-sizing: border-box;
}

/* 絵本画像：装飾なし */
.ehon-image {
    width: 100%;
    height: auto;
    border-radius: 0;
    box-shadow: none;
    display: block;
}

.ehon-text {
    white-space: pre-wrap; 
    margin-top: 30px;
    font-size: 1.4rem;
    line-height: 1.8;
}

/* 広告エリア */
.ad-section {
    width: 100%;
    margin: 80px 0;
    padding: 50px 0;
    background-color: #f5f5f5;
    text-align: center;
    border-top: 1px solid #eee;
    border-bottom: 1px solid #eee;
}

.ad-label {
    font-size: 0.65rem;
    color: #963403;
    opacity: 0.6;
    margin-bottom: 15px;
    letter-spacing: 0.1em;
    text-transform: uppercase;
}

.ad-rectangle {
    width: 300px;
    height: 250px;
    margin: 0 auto;
    background-color: #fff;
    border: 1px solid #ddd;
    display: flex;
    align-items: center;
    justify-content: center;
}

/* ボタン（スマホ対応） */
.nav-section {
    display: flex;
    justify-content: center;
    gap: 15px;
    padding: 60px 15px 120px;
    max-width: 600px;
    margin: 0 auto;
}

.nav-button {
    flex: 1;
    max-width: 200px;
    display: inline-block;
    padding: 18px 10px;
    text-decoration: none;
    font-size: 1.1rem;
    border-radius: 50px;
    text-align: center;
    transition: 0.2s;
    box-sizing: border-box;
}

.nav-button.next { background-color: #963403; color: #fff; }
.nav-button.prev { background-color: #fff; color: #963403; border: 2px solid #963403; }
.nav-button:hover { opacity: 0.8; }

/* フッターデザイン */
footer {
    border-top: 1px solid #eee;
    padding: 60px 20px;
    text-align: center;
    background-color: #fafafa;
}

.footer-nav {
    margin-bottom: 20px;
    display: flex;
    justify-content: center;
    gap: 20px;
}

.footer-nav a {
    color: #963403;
    text-decoration: none;
    font-size: 0.8rem;
    opacity: 0.7;
}

.footer-nav a:hover { opacity: 1; }

.copyright {
    font-size: 0.75rem;
    opacity: 0.5;
    margin: 0;
}