/* ============================================================
   越南文化沉浸课堂 · 典雅古风样式
   配色：墨黑 / 宣纸米黄 / 朱砂红 / 青翠绿 / 鎏金
   字体：Ma Shan Zheng / ZCOOL XiaoWei（书法） · Noto Serif SC（衬线）
   ============================================================ */

:root {
    --ink: #1c1a17;
    --ink-soft: #3a3530;
    --paper: #f3ead3;
    --paper-deep: #e7d9b6;
    --paper-warm: #fbf3dd;
    --vermilion: #a8321e;
    --vermilion-deep: #7a2515;
    --jade: #2f5d4c;
    --jade-soft: #4a7d6a;
    --gold: #b88a3e;
    --gold-soft: #d4ac6a;
    --shadow: rgba(28, 26, 23, 0.18);
    --seal-red: #b03020;
}

* {
    box-sizing: border-box;
    margin: 0;
    padding: 0;
}

html {
    scroll-behavior: smooth;
    scroll-padding-top: 70px;
}

body {
    font-family: "Noto Serif SC", "Songti SC", serif;
    color: var(--ink);
    background-color: var(--paper);
    /* 宣纸纹理 */
    background-image:
        radial-gradient(ellipse at top, rgba(184, 138, 62, 0.08), transparent 60%),
        radial-gradient(ellipse at bottom, rgba(168, 50, 30, 0.04), transparent 60%),
        url("data:image/svg+xml,%3Csvg xmlns='http://www.w3.org/2000/svg' width='200' height='200' viewBox='0 0 200 200'%3E%3Cfilter id='n'%3E%3CfeTurbulence type='fractalNoise' baseFrequency='0.85' numOctaves='2' stitchTiles='stitch'/%3E%3CfeColorMatrix values='0 0 0 0 0.5  0 0 0 0 0.4  0 0 0 0 0.25  0 0 0 0.05 0'/%3E%3C/filter%3E%3Crect width='200' height='200' filter='url(%23n)'/%3E%3C/svg%3E");
    background-attachment: fixed;
    line-height: 1.8;
    overflow-x: hidden;
}

/* ==================== 阅读进度条 ==================== */
.reading-progress {
    position: fixed;
    top: 0;
    left: 0;
    height: 3px;
    width: 0%;
    background: linear-gradient(90deg, var(--vermilion), var(--gold), var(--jade));
    z-index: 1000;
    transition: width 0.15s ease-out;
    box-shadow: 0 0 12px rgba(168, 50, 30, 0.5);
}

/* ==================== 顶部导航 ==================== */
.topnav {
    position: fixed;
    top: 0;
    left: 0;
    right: 0;
    z-index: 100;
    display: flex;
    align-items: center;
    justify-content: space-between;
    padding: 14px 48px;
    background: rgba(243, 234, 211, 0.85);
    backdrop-filter: blur(12px);
    border-bottom: 1px solid rgba(184, 138, 62, 0.25);
    transition: all 0.4s ease;
}

.topnav.scrolled {
    padding: 8px 48px;
    background: rgba(243, 234, 211, 0.95);
    box-shadow: 0 6px 30px var(--shadow);
}

.nav-brand {
    display: flex;
    align-items: center;
    gap: 12px;
}

.nav-seal {
    display: inline-flex;
    align-items: center;
    justify-content: center;
    width: 36px;
    height: 36px;
    background: var(--seal-red);
    color: var(--paper-warm);
    font-family: "Ma Shan Zheng", serif;
    font-size: 22px;
    border-radius: 4px;
    box-shadow: 0 2px 8px rgba(176, 48, 32, 0.5);
    transform: rotate(-3deg);
}

.nav-title {
    font-family: "ZCOOL XiaoWei", serif;
    font-size: 20px;
    color: var(--ink);
    letter-spacing: 2px;
}

.nav-links {
    display: flex;
    list-style: none;
    gap: 32px;
}

.nav-links a {
    position: relative;
    color: var(--ink-soft);
    text-decoration: none;
    font-size: 15px;
    letter-spacing: 1px;
    transition: color 0.3s;
}

.nav-links a::after {
    content: "";
    position: absolute;
    left: 0;
    bottom: -6px;
    width: 0;
    height: 2px;
    background: var(--vermilion);
    transition: width 0.3s ease;
}

.nav-links a:hover {
    color: var(--vermilion);
}

.nav-links a:hover::after {
    width: 100%;
}

.nav-toggle {
    display: none;
    flex-direction: column;
    gap: 5px;
    background: none;
    border: none;
    cursor: pointer;
    padding: 6px;
}

.nav-toggle span {
    width: 24px;
    height: 2px;
    background: var(--ink);
    transition: 0.3s;
}

/* ==================== Hero 序章 ==================== */
.hero {
    position: relative;
    height: 100vh;
    min-height: 640px;
    display: flex;
    align-items: center;
    justify-content: center;
    overflow: hidden;
}

.hero-bg {
    position: absolute;
    inset: 0;
    background-size: cover;
    background-position: center;
    transform: scale(1.05);
    animation: heroZoom 20s ease-in-out infinite alternate;
}

@keyframes heroZoom {
    from { transform: scale(1.05); }
    to { transform: scale(1.18); }
}

.hero-overlay {
    position: absolute;
    inset: 0;
    background:
        radial-gradient(ellipse at center, transparent 0%, rgba(28, 26, 23, 0.5) 100%),
        linear-gradient(180deg, rgba(28, 26, 23, 0.4) 0%, rgba(28, 26, 23, 0.2) 40%, rgba(28, 26, 23, 0.7) 100%);
}

.hero-mist {
    position: absolute;
    inset: 0;
    background:
        radial-gradient(circle at 20% 80%, rgba(243, 234, 211, 0.15) 0%, transparent 40%),
        radial-gradient(circle at 80% 20%, rgba(243, 234, 211, 0.1) 0%, transparent 40%);
    animation: mistFlow 12s ease-in-out infinite alternate;
}

@keyframes mistFlow {
    from { transform: translateX(-30px); opacity: 0.7; }
    to { transform: translateX(30px); opacity: 1; }
}

.hero-content {
    position: relative;
    z-index: 2;
    text-align: center;
    color: var(--paper-warm);
    padding: 0 24px;
}

.hero-vertical {
    position: absolute;
    top: -180px;
    left: 50%;
    transform: translateX(-50%);
    writing-mode: vertical-rl;
    font-family: "Ma Shan Zheng", serif;
    font-size: 22px;
    letter-spacing: 12px;
    color: rgba(251, 243, 221, 0.5);
    opacity: 0;
    animation: fadeInDown 2s ease 0.5s forwards;
}

.hero-title {
    font-family: "Ma Shan Zheng", "ZCOOL XiaoWei", serif;
    font-size: clamp(60px, 9vw, 120px);
    font-weight: 400;
    letter-spacing: 8px;
    margin-bottom: 28px;
    text-shadow: 0 4px 30px rgba(0, 0, 0, 0.6);
}

.title-char {
    display: inline-block;
    opacity: 0;
    transform: translateY(40px) rotateX(-90deg);
    animation: charDrop 0.8s cubic-bezier(0.23, 1, 0.32, 1) forwards;
}

.title-char:nth-child(1) { animation-delay: 0.3s; }
.title-char:nth-child(2) { animation-delay: 0.5s; }
.title-char:nth-child(4) { animation-delay: 0.7s; }
.title-char:nth-child(5) { animation-delay: 0.9s; }
.title-char:nth-child(7) { animation-delay: 1.1s; }
.title-char:nth-child(8) { animation-delay: 1.3s; }

.title-dot {
    display: inline-block;
    color: var(--gold-soft);
    margin: 0 8px;
    opacity: 0;
    animation: fadeIn 0.5s ease 1s forwards;
}

@keyframes charDrop {
    to {
        opacity: 1;
        transform: translateY(0) rotateX(0);
    }
}

@keyframes fadeIn {
    to { opacity: 1; }
}

@keyframes fadeInDown {
    from { opacity: 0; transform: translate(-50%, -20px); }
    to { opacity: 0.5; transform: translate(-50%, 0); }
}

.hero-subtitle {
    font-family: "ZCOOL XiaoWei", serif;
    font-size: 24px;
    letter-spacing: 6px;
    margin-bottom: 16px;
    opacity: 0;
    animation: fadeIn 1.2s ease 1.6s forwards;
}

.hero-poem {
    font-family: "Ma Shan Zheng", serif;
    font-size: 20px;
    color: var(--gold-soft);
    letter-spacing: 4px;
    margin-bottom: 60px;
    opacity: 0;
    animation: fadeIn 1.2s ease 1.9s forwards;
}

.hero-scroll {
    display: inline-flex;
    flex-direction: column;
    align-items: center;
    gap: 14px;
    color: var(--paper-warm);
    text-decoration: none;
    font-family: "ZCOOL XiaoWei", serif;
    font-size: 16px;
    letter-spacing: 4px;
    opacity: 0;
    animation: fadeIn 1s ease 2.2s forwards;
    transition: color 0.3s;
}

.hero-scroll:hover {
    color: var(--gold-soft);
}

.scroll-arrow {
    width: 1px;
    height: 50px;
    background: linear-gradient(180deg, var(--paper-warm), transparent);
    position: relative;
    animation: scrollPulse 2s ease-in-out infinite;
}

.scroll-arrow::after {
    content: "";
    position: absolute;
    bottom: 0;
    left: 50%;
    transform: translateX(-50%) rotate(45deg);
    width: 8px;
    height: 8px;
    border-right: 1px solid var(--paper-warm);
    border-bottom: 1px solid var(--paper-warm);
}

@keyframes scrollPulse {
    0%, 100% { transform: scaleY(1); opacity: 0.6; }
    50% { transform: scaleY(1.2); opacity: 1; }
}

/* ==================== 文化模块通用 ==================== */
.culture-module {
    padding: 120px 48px 100px;
    max-width: 1320px;
    margin: 0 auto;
    position: relative;
}

.module-alt {
    background:
        linear-gradient(180deg, transparent, rgba(184, 138, 62, 0.06) 20%, rgba(184, 138, 62, 0.06) 80%, transparent);
}

.module-header {
    text-align: center;
    margin-bottom: 80px;
    position: relative;
}

.module-index {
    display: inline-flex;
    align-items: center;
    justify-content: center;
    width: 72px;
    height: 72px;
    background: var(--seal-red);
    color: var(--paper-warm);
    font-family: "Ma Shan Zheng", serif;
    font-size: 38px;
    border-radius: 6px;
    margin-bottom: 24px;
    box-shadow: 0 6px 24px rgba(176, 48, 32, 0.4);
    transform: rotate(-4deg);
}

.module-title {
    font-family: "Ma Shan Zheng", serif;
    font-size: clamp(48px, 6vw, 72px);
    font-weight: 400;
    color: var(--ink);
    letter-spacing: 12px;
    margin-bottom: 16px;
    text-shadow: 0 2px 12px rgba(168, 50, 30, 0.15);
}

.module-subtitle {
    font-family: "ZCOOL XiaoWei", serif;
    font-size: 20px;
    color: var(--vermilion-deep);
    letter-spacing: 4px;
    margin-bottom: 24px;
}

.module-divider {
    display: flex;
    align-items: center;
    justify-content: center;
    gap: 16px;
    margin: 0 auto;
    max-width: 360px;
}

.module-divider span {
    flex: 1;
    height: 1px;
    background: linear-gradient(90deg, transparent, var(--gold), transparent);
}

.module-divider .lotus {
    color: var(--vermilion);
    font-size: 20px;
    font-style: normal;
}

.module-layout {
    display: grid;
    grid-template-columns: 1fr;
    gap: 80px;
}

/* ==================== 解析区 ==================== */
.culture-analysis {
    display: grid;
    grid-template-columns: 5fr 6fr;
    gap: 48px;
    align-items: stretch;
}

.analysis-image {
    position: relative;
    background-size: cover;
    background-position: center;
    border-radius: 4px;
    box-shadow: 0 16px 50px var(--shadow);
    min-height: 460px;
    overflow: hidden;
    border: 1px solid rgba(184, 138, 62, 0.3);
}

.analysis-image::after {
    content: "";
    position: absolute;
    inset: 8px;
    border: 1px solid rgba(251, 243, 221, 0.25);
    pointer-events: none;
}

.image-caption {
    position: absolute;
    bottom: 16px;
    left: 16px;
    background: rgba(28, 26, 23, 0.7);
    color: var(--paper-warm);
    padding: 6px 14px;
    font-family: "ZCOOL XiaoWei", serif;
    font-size: 14px;
    letter-spacing: 2px;
    backdrop-filter: blur(4px);
}

.analysis-image-double {
    display: grid;
    grid-template-columns: 1fr 1fr;
    gap: 4px;
    background: var(--ink);
}

.img-half {
    position: relative;
    background-size: cover;
    background-position: center;
    min-height: 460px;
}

.analysis-text {
    display: flex;
    flex-direction: column;
    justify-content: center;
}

.analysis-text h3 {
    font-family: "Ma Shan Zheng", serif;
    font-size: 32px;
    font-weight: 400;
    color: var(--vermilion-deep);
    letter-spacing: 4px;
    margin-bottom: 24px;
    line-height: 1.4;
}

.analysis-text p {
    font-size: 16px;
    line-height: 2;
    color: var(--ink-soft);
    margin-bottom: 16px;
    text-indent: 2em;
    letter-spacing: 0.5px;
}

.emph {
    color: var(--vermilion);
    font-weight: 500;
    border-bottom: 1px dashed rgba(168, 50, 30, 0.4);
    padding: 0 2px;
}

.poem-block {
    margin-top: 28px;
    padding: 28px 32px;
    background: linear-gradient(135deg, var(--paper-warm), var(--paper-deep));
    border-left: 4px solid var(--vermilion);
    border-radius: 2px;
    font-family: "Ma Shan Zheng", "ZCOOL XiaoWei", serif;
    font-size: 22px;
    line-height: 2.2;
    color: var(--ink);
    letter-spacing: 4px;
    text-indent: 0;
    box-shadow: 0 8px 24px var(--shadow);
    position: relative;
}

.poem-block::before {
    content: "“";
    position: absolute;
    top: -10px;
    left: 16px;
    font-size: 60px;
    color: rgba(168, 50, 30, 0.2);
    font-family: serif;
    line-height: 1;
}

.poem-block cite {
    display: block;
    margin-top: 14px;
    font-size: 14px;
    color: var(--ink-soft);
    font-style: normal;
    text-align: right;
    font-family: "Noto Serif SC", serif;
    letter-spacing: 1px;
}

/* ==================== 视频区 ==================== */
.culture-video {
    max-width: 1100px;
    margin: 0 auto;
    width: 100%;
}

.video-frame {
    position: relative;
    background: var(--ink);
    border-radius: 4px;
    overflow: hidden;
    box-shadow: 0 20px 60px var(--shadow);
    border: 1px solid rgba(184, 138, 62, 0.4);
}

.video-frame video {
    display: block;
    width: 100%;
    height: auto;
    aspect-ratio: 16 / 9;
    object-fit: cover;
}

.video-overlay {
    position: absolute;
    inset: 0;
    display: flex;
    flex-direction: column;
    align-items: center;
    justify-content: center;
    gap: 18px;
    background: linear-gradient(180deg, rgba(28, 26, 23, 0.3), rgba(28, 26, 23, 0.5));
    cursor: pointer;
    transition: background 0.4s;
}

.video-overlay:hover {
    background: linear-gradient(180deg, rgba(28, 26, 23, 0.2), rgba(28, 26, 23, 0.4));
}

.video-overlay.playing {
    opacity: 0;
    pointer-events: none;
}

.play-btn {
    width: 84px;
    height: 84px;
    border-radius: 50%;
    background: rgba(251, 243, 221, 0.15);
    border: 2px solid var(--paper-warm);
    cursor: pointer;
    display: flex;
    align-items: center;
    justify-content: center;
    backdrop-filter: blur(8px);
    transition: transform 0.3s, background 0.3s;
    position: relative;
}

.play-btn::before {
    content: "";
    position: absolute;
    inset: -12px;
    border-radius: 50%;
    border: 1px solid rgba(251, 243, 221, 0.4);
    animation: ripple 2s ease-out infinite;
}

@keyframes ripple {
    0% { transform: scale(0.95); opacity: 0.8; }
    100% { transform: scale(1.3); opacity: 0; }
}

.video-overlay:hover .play-btn {
    transform: scale(1.08);
    background: var(--vermilion);
    border-color: var(--vermilion);
}

.play-triangle {
    width: 0;
    height: 0;
    border-left: 22px solid var(--paper-warm);
    border-top: 14px solid transparent;
    border-bottom: 14px solid transparent;
    margin-left: 6px;
}

.video-hint {
    color: var(--paper-warm);
    font-family: "ZCOOL XiaoWei", serif;
    font-size: 16px;
    letter-spacing: 2px;
    text-shadow: 0 2px 8px rgba(0, 0, 0, 0.6);
}

.video-caption {
    padding: 24px 32px;
    background: var(--paper-warm);
    border-top: 1px solid rgba(184, 138, 62, 0.3);
}

.video-caption h4 {
    font-family: "Ma Shan Zheng", serif;
    font-size: 22px;
    font-weight: 400;
    color: var(--vermilion-deep);
    letter-spacing: 3px;
    margin-bottom: 8px;
}

.video-caption p {
    font-size: 14px;
    color: var(--ink-soft);
    line-height: 1.7;
}

/* ==================== 知识测验 ==================== */
.culture-quiz {
    background: linear-gradient(135deg, var(--paper-warm), var(--paper-deep));
    border: 1px solid rgba(184, 138, 62, 0.35);
    border-radius: 4px;
    padding: 40px 48px;
    box-shadow: 0 12px 40px var(--shadow);
    position: relative;
}

.culture-quiz::before {
    content: "";
    position: absolute;
    top: -1px;
    left: 24px;
    right: 24px;
    height: 3px;
    background: linear-gradient(90deg, var(--vermilion), var(--gold), var(--jade));
}

.quiz-header {
    text-align: center;
    margin-bottom: 32px;
}

.quiz-header h3 {
    font-family: "Ma Shan Zheng", serif;
    font-size: 28px;
    font-weight: 400;
    color: var(--ink);
    letter-spacing: 6px;
    margin-bottom: 8px;
}

.quiz-header h3::before,
.quiz-header h3::after {
    content: "◆";
    color: var(--gold);
    font-size: 14px;
    margin: 0 12px;
    vertical-align: middle;
}

.quiz-header p {
    font-size: 14px;
    color: var(--ink-soft);
    letter-spacing: 1px;
}

.quiz-body {
    display: flex;
    flex-direction: column;
    gap: 32px;
}

.quiz-question {
    padding: 24px;
    background: rgba(251, 243, 221, 0.5);
    border-radius: 4px;
    border: 1px solid rgba(184, 138, 62, 0.2);
}

.quiz-question .q-index {
    display: inline-flex;
    align-items: center;
    justify-content: center;
    width: 28px;
    height: 28px;
    background: var(--jade);
    color: var(--paper-warm);
    font-family: "ZCOOL XiaoWei", serif;
    font-size: 16px;
    border-radius: 50%;
    margin-right: 10px;
    vertical-align: middle;
}

.quiz-question .q-text {
    display: inline;
    font-size: 17px;
    color: var(--ink);
    line-height: 1.7;
    vertical-align: middle;
}

.quiz-options {
    display: grid;
    grid-template-columns: 1fr 1fr;
    gap: 12px;
    margin-top: 18px;
}

.quiz-option {
    display: flex;
    align-items: center;
    gap: 12px;
    padding: 14px 18px;
    background: var(--paper-warm);
    border: 1px solid rgba(184, 138, 62, 0.3);
    border-radius: 4px;
    cursor: pointer;
    font-size: 15px;
    color: var(--ink-soft);
    transition: all 0.25s ease;
    text-align: left;
    font-family: inherit;
}

.quiz-option:hover:not(.locked) {
    border-color: var(--vermilion);
    background: rgba(168, 50, 30, 0.05);
    transform: translateY(-2px);
}

.quiz-option .opt-letter {
    display: inline-flex;
    align-items: center;
    justify-content: center;
    width: 26px;
    height: 26px;
    background: var(--paper-deep);
    color: var(--ink);
    border-radius: 50%;
    font-size: 14px;
    font-weight: 600;
    flex-shrink: 0;
    transition: all 0.25s;
}

.quiz-option.correct {
    background: rgba(47, 93, 76, 0.15);
    border-color: var(--jade);
    color: var(--jade);
}

.quiz-option.correct .opt-letter {
    background: var(--jade);
    color: var(--paper-warm);
}

.quiz-option.wrong {
    background: rgba(168, 50, 30, 0.1);
    border-color: var(--vermilion);
    color: var(--vermilion);
    opacity: 0.7;
}

.quiz-option.wrong .opt-letter {
    background: var(--vermilion);
    color: var(--paper-warm);
}

.quiz-option.locked {
    cursor: default;
}

.quiz-feedback {
    margin-top: 14px;
    padding: 12px 16px;
    background: rgba(184, 138, 62, 0.1);
    border-left: 3px solid var(--gold);
    font-size: 14px;
    color: var(--ink-soft);
    line-height: 1.7;
    border-radius: 2px;
    display: none;
}

.quiz-feedback.show {
    display: block;
    animation: fadeIn 0.4s ease;
}

.quiz-feedback.correct {
    background: rgba(47, 93, 76, 0.1);
    border-left-color: var(--jade);
}

.quiz-feedback.wrong {
    background: rgba(168, 50, 30, 0.08);
    border-left-color: var(--vermilion);
}

.quiz-score {
    margin-top: 24px;
    padding: 18px;
    background: var(--ink);
    color: var(--paper-warm);
    text-align: center;
    border-radius: 4px;
    font-family: "Ma Shan Zheng", serif;
    font-size: 20px;
    letter-spacing: 4px;
    display: none;
}

.quiz-score.show {
    display: block;
    animation: fadeIn 0.6s ease;
}

.quiz-score .score-num {
    color: var(--gold-soft);
    font-size: 28px;
}

/* ==================== 结语 ==================== */
.epilogue {
    margin-top: 80px;
    padding: 100px 48px 40px;
    background: linear-gradient(180deg, var(--paper) 0%, var(--ink) 100%);
    text-align: center;
    color: var(--paper-warm);
    position: relative;
}

.epilogue-inner h2 {
    font-family: "Ma Shan Zheng", serif;
    font-size: 48px;
    font-weight: 400;
    color: var(--paper-warm);
    letter-spacing: 12px;
    margin-bottom: 24px;
}

.epilogue-inner .module-divider span {
    background: linear-gradient(90deg, transparent, var(--gold-soft), transparent);
}

.epilogue-inner p {
    font-size: 17px;
    line-height: 2.2;
    color: rgba(251, 243, 221, 0.85);
    letter-spacing: 2px;
    max-width: 720px;
    margin: 24px auto;
}

.epilogue-seal {
    margin-top: 40px;
    font-family: "Ma Shan Zheng", serif;
    font-size: 32px;
    color: var(--gold-soft);
    letter-spacing: 16px;
}

.footer-credit {
    margin-top: 80px;
    padding-top: 24px;
    border-top: 1px solid rgba(251, 243, 221, 0.15);
    font-size: 12px;
    color: rgba(251, 243, 221, 0.5);
    line-height: 1.8;
}

.footer-credit .sources {
    margin-top: 6px;
    font-size: 11px;
    opacity: 0.7;
}

/* ==================== 朗诵浮层 ==================== */
.narration-bar {
    position: fixed;
    bottom: 24px;
    left: 50%;
    transform: translateX(-50%);
    z-index: 200;
    display: flex;
    align-items: center;
    gap: 16px;
    padding: 14px 24px;
    background: var(--ink);
    color: var(--paper-warm);
    border-radius: 50px;
    box-shadow: 0 12px 40px rgba(0, 0, 0, 0.4);
    border: 1px solid rgba(184, 138, 62, 0.4);
    max-width: 90vw;
    animation: narrationIn 0.4s ease;
}

@keyframes narrationIn {
    from { transform: translate(-50%, 30px); opacity: 0; }
    to { transform: translate(-50%, 0); opacity: 1; }
}

.narration-wave {
    display: flex;
    align-items: center;
    gap: 3px;
    height: 24px;
}

.narration-wave span {
    width: 3px;
    height: 100%;
    background: var(--gold-soft);
    border-radius: 2px;
    animation: wave 1s ease-in-out infinite;
}

.narration-wave span:nth-child(2) { animation-delay: 0.1s; }
.narration-wave span:nth-child(3) { animation-delay: 0.2s; }
.narration-wave span:nth-child(4) { animation-delay: 0.3s; }
.narration-wave span:nth-child(5) { animation-delay: 0.4s; }

@keyframes wave {
    0%, 100% { transform: scaleY(0.4); }
    50% { transform: scaleY(1); }
}

.narration-text {
    font-family: "Ma Shan Zheng", serif;
    font-size: 16px;
    letter-spacing: 2px;
    white-space: nowrap;
    overflow: hidden;
    text-overflow: ellipsis;
    max-width: 460px;
}

.narration-stop {
    background: none;
    border: none;
    color: var(--paper-warm);
    font-size: 24px;
    cursor: pointer;
    padding: 0 4px;
    line-height: 1;
    opacity: 0.7;
    transition: opacity 0.2s;
}

.narration-stop:hover {
    opacity: 1;
}

/* ==================== 回到顶部 ==================== */
.back-to-top {
    position: fixed;
    bottom: 24px;
    right: 24px;
    z-index: 200;
    width: 48px;
    height: 48px;
    background: var(--seal-red);
    color: var(--paper-warm);
    border: none;
    border-radius: 4px;
    font-family: "Ma Shan Zheng", serif;
    font-size: 20px;
    cursor: pointer;
    box-shadow: 0 8px 24px rgba(176, 48, 32, 0.4);
    opacity: 0;
    transform: translateY(20px);
    transition: all 0.4s ease;
    pointer-events: none;
}

.back-to-top.show {
    opacity: 1;
    transform: translateY(0);
    pointer-events: auto;
}

.back-to-top:hover {
    background: var(--vermilion-deep);
    transform: translateY(-4px);
}

/* ==================== 滚动渐显 ==================== */
.reveal {
    opacity: 0;
    transform: translateY(40px);
    transition: opacity 1s ease, transform 1s ease;
}

.reveal.visible {
    opacity: 1;
    transform: translateY(0);
}

/* ==================== 响应式 ==================== */
@media (max-width: 960px) {
    .topnav {
        padding: 12px 24px;
    }
    .nav-links {
        position: fixed;
        top: 60px;
        right: 0;
        flex-direction: column;
        background: var(--paper-warm);
        padding: 24px;
        gap: 18px;
        border-left: 1px solid rgba(184, 138, 62, 0.3);
        box-shadow: -8px 0 30px var(--shadow);
        transform: translateX(100%);
        transition: transform 0.4s;
        height: calc(100vh - 60px);
    }
    .nav-links.open {
        transform: translateX(0);
    }
    .nav-toggle {
        display: flex;
    }
    .nav-toggle.active span:nth-child(1) {
        transform: rotate(45deg) translate(5px, 5px);
    }
    .nav-toggle.active span:nth-child(2) {
        opacity: 0;
    }
    .nav-toggle.active span:nth-child(3) {
        transform: rotate(-45deg) translate(7px, -7px);
    }
    .culture-module {
        padding: 80px 24px;
    }
    .culture-analysis {
        grid-template-columns: 1fr;
        gap: 32px;
    }
    .analysis-image,
    .img-half {
        min-height: 320px;
    }
    .quiz-options {
        grid-template-columns: 1fr;
    }
    .culture-quiz {
        padding: 28px 20px;
    }
    .hero-vertical {
        display: none;
    }
    .epilogue {
        padding: 80px 24px 40px;
    }
    .module-title {
        letter-spacing: 6px;
    }
}

@media (max-width: 600px) {
    .nav-title {
        display: none;
    }
    .hero-title {
        letter-spacing: 4px;
    }
    .analysis-text h3 {
        font-size: 24px;
    }
    .poem-block {
        font-size: 18px;
        padding: 20px;
    }
}

/* ==================== 无障碍 ==================== */
@media (prefers-reduced-motion: reduce) {
    *, *::before, *::after {
        animation-duration: 0.01ms !important;
        animation-iteration-count: 1 !important;
        transition-duration: 0.01ms !important;
    }
    .reveal {
        opacity: 1;
        transform: none;
    }
}

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