:root {
    --bg: #151515;
    --surface: #202020;
    --surface-hover: #303030;
    --text: #e8e8e8;
    --muted: #a8a8a8;
    --accent: #c9a96e;
    --border: #353535;
}

* {
    box-sizing: border-box;
}

html {
    background: var(--bg);
}

body {
    margin: 0;
    padding: 0;
    background: var(--bg);
    color: var(--text);
    font-family:
        "Meiryo",
        "メイリオ",
        "Yu Gothic",
        "游ゴシック",
        sans-serif;
    font-size: 16px;
    font-weight: 500;
    line-height: 1.8;
}


/* ==============================
   Header
   ============================== */

.site-header {
    width: 100%;
    padding: 24px 16px 16px;
    text-align: center;
}

.site-nav {
    display: flex;
    flex-wrap: wrap;
    justify-content: center;
    align-items: center;
    gap: 0 10px;
    margin: 0;
    padding: 0;
}

.site-nav a {
    color: var(--text);
    text-decoration: none;
    font-weight: 600;
    transition:
        color 0.2s ease,
        opacity 0.2s ease;
}

.site-nav a:hover,
.site-nav a:focus {
    color: var(--accent);
}

.site-nav span {
    color: var(--muted);
}


/* ==============================
   Main
   ============================== */

.page-container {
    width: min(900px, calc(100% - 32px));
    margin: 0 auto;
    padding: 16px 0 48px;
}


/* ==============================
   Page heading
   ============================== */

.page-heading {
    margin: 0 0 32px;
    text-align: center;
}

.page-heading h1 {
    margin: 0;
    padding: 0;
    color: var(--text);
    font-size: clamp(24px, 4vw, 32px);
    font-weight: 700;
    line-height: 1.4;
}


/* ==============================
   Book detail
   ============================== */

.book-detail {
    display: grid;
    grid-template-columns: 220px minmax(0, 1fr);
    gap: 40px;
    align-items: start;
    margin: 0 auto;
    padding: 0;
}


/* ==============================
   Book cover
   ============================== */

.book-cover {
    display: flex;
    justify-content: center;
    align-items: flex-start;
    width: 100%;
}

.book-cover img {
    display: block;
    width: 200px;
    height: auto;
    max-width: 100%;
    object-fit: contain;
}


/* ==============================
   Book information
   ============================== */

.book-information {
    min-width: 0;
}

.book-meta {
    display: grid;
    grid-template-columns: 100px minmax(0, 1fr);
    margin: 0;
    padding: 0;
}

.book-meta dt,
.book-meta dd {
    margin: 0;
    padding: 10px 0;
}

.book-meta dt {
    color: var(--muted);
    font-weight: 700;
}

.book-meta dd {
    color: var(--text);
    min-width: 0;
    overflow-wrap: break-word;
}


/* ==============================
   Review
   ============================== */

.review-section {
    margin: 48px 0 0;
    padding: 0;
}

.review-section:empty {
    display: none;
}

.review-section h2 {
    margin: 0 0 16px;
    padding: 0;
    color: var(--text);
    font-size: 21px;
    font-weight: 700;
    line-height: 1.5;
}

.review-section p {
    margin: 0;
    padding: 0;
    color: var(--text);
}


/* ==============================
   Footer
   ============================== */

.site-footer {
    width: 100%;
    padding: 32px 16px 40px;
    text-align: center;
}

.site-footer .site-nav {
    margin-bottom: 24px;
}

.copyright {
    margin: 8px 0 0;
    color: var(--muted);
    font-size: 13px;
    line-height: 1.7;
}


/* ==============================
   Link focus
   ============================== */

a:focus-visible {
    outline: 2px solid var(--accent);
    outline-offset: 3px;
}


/* ==============================
   Smartphone
   ============================== */

@media (max-width: 700px) {

    .site-header {
        padding: 20px 12px 14px;
    }

    .site-nav {
        gap: 2px 8px;
        font-size: 14px;
    }

    .page-container {
        width: min(100% - 24px, 600px);
        padding: 12px 0 40px;
    }

    .page-heading {
        margin-bottom: 28px;
    }

    .page-heading h1 {
        font-size: 24px;
    }

    .book-detail {
        grid-template-columns: 140px minmax(0, 1fr);
        gap: 24px;
    }

    .book-cover img {
        width: 140px;
    }

    .book-meta {
        grid-template-columns: 78px minmax(0, 1fr);
        font-size: 14px;
    }

    .book-meta dt,
    .book-meta dd {
        padding: 8px 0;
    }

    .review-section {
        margin-top: 40px;
    }

    .review-section h2 {
        font-size: 19px;
    }

    .site-footer {
        padding: 28px 12px 36px;
    }

    .copyright {
        font-size: 12px;
    }
}


/* ==============================
   Small smartphone
   ============================== */

@media (max-width: 480px) {

    .book-detail {
        grid-template-columns: 1fr;
        gap: 24px;
    }

    .book-cover {
        justify-content: center;
    }

    .book-cover img {
        width: 180px;
    }

    .book-information {
        width: 100%;
    }

    .book-meta {
        grid-template-columns: 90px minmax(0, 1fr);
        font-size: 14px;
    }
}


/* ==============================
   Reduced motion
   ============================== */

@media (prefers-reduced-motion: reduce) {

    .site-nav a {
        transition: none;
    }
}