/* ========================================
   围产期微塑料暴露健康风险科普网页
   苹果官网风格 CSS
   ======================================== */

/* CSS变量 */
:root {
    --bg-primary: #f5f5f7;
    --bg-secondary: #ffffff;
    --bg-dark: #1d1d1f;
    --text-primary: #1d1d1f;
    --text-secondary: #86868b;
    --accent: #0071e3;
    --accent-hover: #0077ed;
    --warning: #ff3b30;
    --success: #34c759;
    --border: #d2d2d7;
    --shadow-sm: 0 2px 8px rgba(0,0,0,0.08);
    --shadow-md: 0 4px 16px rgba(0,0,0,0.12);
    --shadow-lg: 0 8px 32px rgba(0,0,0,0.16);
    --radius-sm: 8px;
    --radius-md: 12px;
    --radius-lg: 18px;
    --radius-xl: 28px;
    --transition: all 0.3s cubic-bezier(0.4, 0, 0.2, 1);
}

/* 重置 */
*, *::before, *::after {
    box-sizing: border-box;
    margin: 0;
    padding: 0;
}

html {
    scroll-behavior: smooth;
    -webkit-font-smoothing: antialiased;
    -moz-osx-font-smoothing: grayscale;
}

body {
    font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", "PingFang SC", "Hiragino Sans GB", "Microsoft YaHei", sans-serif;
    background-color: var(--bg-primary);
    color: var(--text-primary);
    line-height: 1.6;
    overflow-x: hidden;
}

img {
    max-width: 100%;
    height: auto;
    display: block;
}

a {
    color: var(--accent);
    text-decoration: none;
    transition: var(--transition);
}

a:hover {
    color: var(--accent-hover);
}

/* 容器 */
.container {
    max-width: 980px;
    margin: 0 auto;
    padding: 0 24px;
}

@media (min-width: 768px) {
    .container {
        padding: 0 48px;
    }
}

/* ========================================
   导航栏
   ======================================== */
.navbar {
    position: fixed;
    top: 0;
    left: 0;
    right: 0;
    height: 52px;
    background: rgba(255, 255, 255, 0.8);
    backdrop-filter: saturate(180%) blur(20px);
    -webkit-backdrop-filter: saturate(180%) blur(20px);
    border-bottom: 1px solid rgba(0, 0, 0, 0.05);
    z-index: 1000;
    transition: var(--transition);
}

.navbar.scrolled {
    box-shadow: var(--shadow-sm);
}

.nav-container {
    max-width: 1024px;
    height: 100%;
    margin: 0 auto;
    padding: 0 20px;
    display: flex;
    align-items: center;
    justify-content: space-between;
}

.nav-logo {
    display: flex;
    align-items: center;
    gap: 8px;
    color: var(--text-primary);
    font-weight: 600;
    font-size: 15px;
}

.nav-logo svg {
    color: var(--accent);
}

.nav-toggle {
    display: flex;
    flex-direction: column;
    gap: 5px;
    background: none;
    border: none;
    cursor: pointer;
    padding: 8px;
}

.nav-toggle span {
    display: block;
    width: 22px;
    height: 2px;
    background: var(--text-primary);
    transition: var(--transition);
}

.nav-toggle.active span:nth-child(1) {
    transform: translateY(7px) rotate(45deg);
}

.nav-toggle.active span:nth-child(2) {
    opacity: 0;
}

.nav-toggle.active span:nth-child(3) {
    transform: translateY(-7px) rotate(-45deg);
}

.nav-menu {
    position: absolute;
    top: 52px;
    left: 0;
    right: 0;
    background: rgba(255, 255, 255, 0.95);
    backdrop-filter: blur(20px);
    list-style: none;
    padding: 20px;
    transform: translateY(-100%);
    opacity: 0;
    visibility: hidden;
    transition: var(--transition);
}

.nav-menu.active {
    transform: translateY(0);
    opacity: 1;
    visibility: visible;
}

.nav-menu li {
    margin-bottom: 4px;
}

.nav-link {
    display: block;
    padding: 12px 16px;
    color: var(--text-primary);
    font-size: 15px;
    border-radius: var(--radius-sm);
    transition: var(--transition);
}

.nav-link:hover {
    background: rgba(0, 113, 227, 0.08);
    color: var(--accent);
}

@media (min-width: 768px) {
    .nav-toggle {
        display: none;
    }

    .nav-menu {
        position: static;
        display: flex;
        gap: 8px;
        padding: 0;
        transform: none;
        opacity: 1;
        visibility: visible;
        background: transparent;
        backdrop-filter: none;
    }

    .nav-menu li {
        margin-bottom: 0;
    }

    .nav-link {
        padding: 8px 12px;
        font-size: 13px;
    }
}

/* ========================================
   Hero区域
   ======================================== */
.hero {
    min-height: 100vh;
    display: flex;
    flex-direction: column;
    align-items: center;
    justify-content: center;
    text-align: center;
    padding: 100px 24px 60px;
    background: linear-gradient(180deg, #f5f5f7 0%, #ffffff 100%);
    position: relative;
}

.hero-content {
    max-width: 700px;
    animation: fadeInUp 0.8s ease-out;
}

.hero-label {
    font-size: 14px;
    font-weight: 600;
    color: var(--accent);
    text-transform: uppercase;
    letter-spacing: 2px;
    margin-bottom: 16px;
}

.hero-title {
    font-size: clamp(32px, 8vw, 56px);
    font-weight: 700;
    line-height: 1.1;
    margin-bottom: 20px;
    letter-spacing: -0.02em;
}

.gradient-text {
    background: linear-gradient(135deg, #0071e3 0%, #42a5f5 50%, #0071e3 100%);
    -webkit-background-clip: text;
    -webkit-text-fill-color: transparent;
    background-clip: text;
}

.hero-subtitle {
    font-size: clamp(18px, 4vw, 24px);
    color: var(--text-secondary);
    margin-bottom: 40px;
    font-weight: 400;
}

.hero-stats {
    display: flex;
    flex-wrap: wrap;
    justify-content: center;
    gap: 32px;
    margin-bottom: 48px;
}

.stat-item {
    display: flex;
    flex-direction: column;
    align-items: center;
}

.stat-number {
    font-size: clamp(28px, 6vw, 40px);
    font-weight: 700;
    color: var(--text-primary);
    line-height: 1;
}

.stat-label {
    font-size: 13px;
    color: var(--text-secondary);
    margin-top: 4px;
    max-width: 120px;
    text-align: center;
}

.hero-cta {
    display: inline-block;
    padding: 14px 32px;
    background: var(--accent);
    color: white;
    font-size: 16px;
    font-weight: 600;
    border-radius: 980px;
    transition: var(--transition);
    box-shadow: 0 4px 16px rgba(0, 113, 227, 0.3);
}

.hero-cta:hover {
    background: var(--accent-hover);
    transform: scale(1.02);
    color: white;
    box-shadow: 0 6px 20px rgba(0, 113, 227, 0.4);
}

.hero-scroll {
    position: absolute;
    bottom: 32px;
    left: 50%;
    transform: translateX(-50%);
    color: var(--text-secondary);
    animation: bounce 2s infinite;
}

@keyframes bounce {
    0%, 20%, 50%, 80%, 100% {
        transform: translateX(-50%) translateY(0);
    }
    40% {
        transform: translateX(-50%) translateY(-10px);
    }
    60% {
        transform: translateX(-50%) translateY(-5px);
    }
}

@keyframes fadeInUp {
    from {
        opacity: 0;
        transform: translateY(30px);
    }
    to {
        opacity: 1;
        transform: translateY(0);
    }
}

/* ========================================
   通用区块样式
   ======================================== */
.section {
    padding: 80px 0;
}

.section-header {
    text-align: center;
    margin-bottom: 48px;
}

.section-title {
    font-size: clamp(28px, 6vw, 40px);
    font-weight: 700;
    margin-bottom: 12px;
    letter-spacing: -0.02em;
}

.section-subtitle {
    font-size: 18px;
    color: var(--text-secondary);
}

.subsection-title {
    font-size: clamp(22px, 5vw, 28px);
    font-weight: 600;
    margin-bottom: 32px;
    text-align: center;
}

/* ========================================
   什么是微塑料
   ======================================== */
.what-grid {
    display: grid;
    gap: 24px;
}

@media (min-width: 768px) {
    .what-grid {
        grid-template-columns: repeat(2, 1fr);
    }

    .what-card.highlight {
        grid-column: span 2;
    }
}

.what-card {
    background: var(--bg-secondary);
    border-radius: var(--radius-lg);
    padding: 32px;
    box-shadow: var(--shadow-sm);
    transition: var(--transition);
    opacity: 0;
    transform: translateY(20px);
}

.what-card.visible {
    opacity: 1;
    transform: translateY(0);
}

.what-card:hover {
    box-shadow: var(--shadow-md);
    transform: translateY(-4px);
}

.what-icon {
    width: 56px;
    height: 56px;
    background: linear-gradient(135deg, rgba(0, 113, 227, 0.1) 0%, rgba(0, 113, 227, 0.05) 100%);
    border-radius: var(--radius-md);
    display: flex;
    align-items: center;
    justify-content: center;
    margin-bottom: 20px;
}

.what-card h3 {
    font-size: 20px;
    font-weight: 600;
    margin-bottom: 12px;
}

.what-card p {
    color: var(--text-secondary);
    margin-bottom: 16px;
}

.what-list {
    list-style: none;
}

.what-list li {
    padding: 8px 0;
    padding-left: 20px;
    position: relative;
    color: var(--text-secondary);
    font-size: 15px;
}

.what-list li::before {
    content: "";
    position: absolute;
    left: 0;
    top: 16px;
    width: 6px;
    height: 6px;
    background: var(--accent);
    border-radius: 50%;
}

.what-list.warning li::before {
    background: var(--warning);
}

.what-list strong {
    color: var(--text-primary);
}

.plastic-types {
    display: flex;
    flex-wrap: wrap;
    gap: 12px;
    margin-bottom: 16px;
}

.plastic-type {
    display: flex;
    align-items: center;
    gap: 8px;
    padding: 8px 12px;
    background: var(--bg-primary);
    border-radius: var(--radius-sm);
    font-size: 14px;
}

.type-tag {
    padding: 2px 8px;
    border-radius: 4px;
    font-weight: 600;
    font-size: 12px;
    color: white;
}

.type-tag.ps { background: #e53935; }
.type-tag.pe { background: #43a047; }
.type-tag.pp { background: #fb8c00; }
.type-tag.pvc { background: #1e88e5; }
.type-tag.pet { background: #8e24aa; }

.plastic-note {
    font-size: 13px;
    padding: 12px;
    background: rgba(0, 113, 227, 0.05);
    border-radius: var(--radius-sm);
    border-left: 3px solid var(--accent);
}

.what-card.highlight .what-icon {
    background: rgba(255, 59, 48, 0.1);
}

.what-card.highlight h3 {
    color: var(--warning);
}

/* ========================================
   暴露途径
   ======================================== */
.section-exposure {
    background: var(--bg-secondary);
}

.exposure-content {
    display: grid;
    gap: 32px;
}

@media (min-width: 768px) {
    .exposure-content {
        grid-template-columns: 1.2fr 1fr;
        align-items: center;
    }
}

.exposure-image {
    border-radius: var(--radius-lg);
    overflow: hidden;
    box-shadow: var(--shadow-md);
}

.exposure-image img {
    width: 100%;
    transition: transform 0.5s ease;
}

.exposure-image:hover img {
    transform: scale(1.02);
}

.exposure-paths {
    display: flex;
    flex-direction: column;
    gap: 20px;
}

.path-item {
    display: flex;
    align-items: flex-start;
    gap: 16px;
    padding: 20px;
    background: var(--bg-primary);
    border-radius: var(--radius-md);
    transition: var(--transition);
    opacity: 0;
    transform: translateX(20px);
}

.path-item.visible {
    opacity: 1;
    transform: translateX(0);
}

.path-item:hover {
    box-shadow: var(--shadow-sm);
}

.path-icon {
    font-size: 32px;
    flex-shrink: 0;
}

.path-info {
    flex: 1;
}

.path-info h4 {
    font-size: 17px;
    font-weight: 600;
    margin-bottom: 4px;
}

.path-info p {
    font-size: 14px;
    color: var(--text-secondary);
    margin-bottom: 8px;
}

.path-percent {
    display: inline-block;
    padding: 4px 12px;
    background: var(--accent);
    color: white;
    font-size: 13px;
    font-weight: 600;
    border-radius: 980px;
}

/* ========================================
   胎盘屏障
   ======================================== */
.placenta-content {
    display: grid;
    gap: 32px;
}

@media (min-width: 768px) {
    .placenta-content {
        grid-template-columns: 1fr 1fr;
    }
}

.placenta-image {
    border-radius: var(--radius-lg);
    overflow: hidden;
    box-shadow: var(--shadow-md);
}

.placenta-image img {
    width: 100%;
}

.placenta-info {
    display: flex;
    flex-direction: column;
    gap: 20px;
}

.info-box {
    padding: 24px;
    background: var(--bg-secondary);
    border-radius: var(--radius-md);
    box-shadow: var(--shadow-sm);
}

.info-box h4 {
    font-size: 16px;
    font-weight: 600;
    margin-bottom: 16px;
}

.info-box ul {
    list-style: none;
}

.info-box li {
    padding: 8px 0;
    padding-left: 20px;
    position: relative;
    font-size: 15px;
    color: var(--text-secondary);
}

.info-box li::before {
    content: "";
    position: absolute;
    left: 0;
    top: 14px;
    width: 8px;
    height: 8px;
    background: var(--accent);
    border-radius: 2px;
}

.info-box.warning {
    border-left: 4px solid var(--warning);
}

.info-box.warning li::before {
    background: var(--warning);
}

/* ========================================
   健康影响
   ======================================== */
.section-health {
    background: var(--bg-secondary);
}

.health-content {
    display: flex;
    flex-direction: column;
    gap: 48px;
}

.health-image-grid {
    display: grid;
    gap: 24px;
}

@media (min-width: 768px) {
    .health-image-grid {
        grid-template-columns: repeat(2, 1fr);
    }
}

.health-image-item {
    background: var(--bg-primary);
    border-radius: var(--radius-lg);
    overflow: hidden;
    box-shadow: var(--shadow-sm);
    transition: var(--transition);
}

.health-image-item:hover {
    box-shadow: var(--shadow-md);
}

.health-image-item img {
    width: 100%;
}

.image-caption {
    padding: 16px;
    font-size: 14px;
    color: var(--text-secondary);
    text-align: center;
}

.health-effects {
    display: grid;
    gap: 24px;
}

@media (min-width: 768px) {
    .health-effects {
        grid-template-columns: repeat(3, 1fr);
    }
}

.effect-card {
    padding: 28px;
    background: var(--bg-primary);
    border-radius: var(--radius-lg);
    transition: var(--transition);
    opacity: 0;
    transform: translateY(20px);
}

.effect-card.visible {
    opacity: 1;
    transform: translateY(0);
}

.effect-card:hover {
    transform: translateY(-4px);
    box-shadow: var(--shadow-md);
}

.effect-header {
    display: flex;
    align-items: center;
    gap: 12px;
    margin-bottom: 16px;
}

.effect-icon {
    font-size: 28px;
}

.effect-header h4 {
    font-size: 18px;
    font-weight: 600;
}

.effect-list {
    list-style: none;
}

.effect-list li {
    padding: 8px 0;
    font-size: 14px;
    color: var(--text-secondary);
    border-bottom: 1px solid var(--border);
}

.effect-list li:last-child {
    border-bottom: none;
}

.effect-list strong {
    color: var(--text-primary);
}

/* ========================================
   日常生活模块
   ======================================== */
.section-daily {
    background: linear-gradient(180deg, #f5f5f7 0%, #ffffff 100%);
}

/* FAQ折叠面板 */
.faq-section {
    margin-bottom: 64px;
}

.faq-list {
    display: flex;
    flex-direction: column;
    gap: 12px;
}

.faq-item {
    background: var(--bg-secondary);
    border-radius: var(--radius-md);
    overflow: hidden;
    box-shadow: var(--shadow-sm);
}

.faq-question {
    width: 100%;
    display: flex;
    align-items: center;
    justify-content: space-between;
    padding: 20px 24px;
    background: none;
    border: none;
    font-size: 16px;
    font-weight: 600;
    text-align: left;
    cursor: pointer;
    color: var(--text-primary);
    transition: var(--transition);
}

.faq-question:hover {
    background: rgba(0, 113, 227, 0.03);
}

.faq-icon {
    transition: transform 0.3s ease;
    flex-shrink: 0;
    margin-left: 16px;
}

.faq-item.active .faq-icon {
    transform: rotate(180deg);
}

.faq-answer {
    max-height: 0;
    overflow: hidden;
    transition: max-height 0.3s ease, padding 0.3s ease;
}

.faq-item.active .faq-answer {
    max-height: 300px;
    padding: 0 24px 20px;
}

.faq-answer p {
    color: var(--text-secondary);
    font-size: 15px;
    line-height: 1.7;
}

/* 防护建议 */
.protection-section {
    margin-bottom: 64px;
}

.protection-grid {
    display: grid;
    gap: 20px;
}

@media (min-width: 640px) {
    .protection-grid {
        grid-template-columns: repeat(2, 1fr);
    }
}

.protection-card {
    padding: 28px;
    background: var(--bg-secondary);
    border-radius: var(--radius-lg);
    box-shadow: var(--shadow-sm);
    transition: var(--transition);
    opacity: 0;
    transform: translateY(20px);
}

.protection-card.visible {
    opacity: 1;
    transform: translateY(0);
}

.protection-card:hover {
    box-shadow: var(--shadow-md);
}

.protection-icon {
    font-size: 36px;
    margin-bottom: 16px;
}

.protection-card h4 {
    font-size: 18px;
    font-weight: 600;
    margin-bottom: 16px;
}

.protection-card ul {
    list-style: none;
}

.protection-card li {
    padding: 8px 0;
    padding-left: 20px;
    position: relative;
    font-size: 14px;
    color: var(--text-secondary);
}

.protection-card li::before {
    content: "✓";
    position: absolute;
    left: 0;
    color: var(--success);
    font-weight: 700;
}

/* 自查清单 */
.quiz-section {
    margin-bottom: 64px;
}

.quiz-container {
    background: var(--bg-secondary);
    border-radius: var(--radius-lg);
    padding: 32px;
    box-shadow: var(--shadow-sm);
}

.quiz-intro {
    text-align: center;
    color: var(--text-secondary);
    margin-bottom: 24px;
}

.quiz-form {
    display: grid;
    gap: 24px;
    margin-bottom: 32px;
}

@media (min-width: 768px) {
    .quiz-form {
        grid-template-columns: repeat(3, 1fr);
    }
}

.quiz-category h4 {
    font-size: 16px;
    font-weight: 600;
    margin-bottom: 16px;
    color: var(--text-primary);
}

.quiz-item {
    display: flex;
    align-items: flex-start;
    gap: 12px;
    padding: 12px;
    cursor: pointer;
    border-radius: var(--radius-sm);
    transition: var(--transition);
}

.quiz-item:hover {
    background: var(--bg-primary);
}

.quiz-item input[type="checkbox"] {
    width: 20px;
    height: 20px;
    margin-top: 2px;
    accent-color: var(--accent);
    cursor: pointer;
}

.quiz-item span {
    font-size: 14px;
    color: var(--text-secondary);
    flex: 1;
}

.quiz-result {
    text-align: center;
    padding: 32px;
    background: var(--bg-primary);
    border-radius: var(--radius-md);
}

.result-content {
    margin-bottom: 20px;
}

.result-score {
    font-size: 48px;
    font-weight: 700;
    color: var(--accent);
}

.result-label {
    font-size: 24px;
    color: var(--text-secondary);
}

.result-text {
    font-size: 15px;
    color: var(--text-secondary);
    margin-top: 8px;
}

.quiz-btn {
    padding: 14px 40px;
    background: var(--accent);
    color: white;
    font-size: 16px;
    font-weight: 600;
    border: none;
    border-radius: 980px;
    cursor: pointer;
    transition: var(--transition);
}

.quiz-btn:hover {
    background: var(--accent-hover);
    transform: scale(1.02);
}

/* 误区澄清 */
.myths-section {
    margin-bottom: 64px;
}

.myths-grid {
    display: grid;
    gap: 20px;
}

@media (min-width: 768px) {
    .myths-grid {
        grid-template-columns: repeat(2, 1fr);
    }
}

.myth-card {
    background: var(--bg-secondary);
    border-radius: var(--radius-lg);
    overflow: hidden;
    box-shadow: var(--shadow-sm);
    transition: var(--transition);
    opacity: 0;
    transform: translateY(20px);
}

.myth-card.visible {
    opacity: 1;
    transform: translateY(0);
}

.myth-card:hover {
    box-shadow: var(--shadow-md);
}

.myth-header {
    display: flex;
    align-items: flex-start;
    gap: 12px;
    padding: 20px;
    background: rgba(255, 59, 48, 0.05);
}

.myth-icon {
    font-size: 20px;
    flex-shrink: 0;
}

.myth-text {
    font-size: 15px;
    color: var(--text-primary);
    line-height: 1.5;
}

.truth {
    display: flex;
    align-items: flex-start;
    gap: 12px;
    padding: 20px;
}

.truth-icon {
    font-size: 20px;
    flex-shrink: 0;
}

.truth p {
    font-size: 14px;
    color: var(--text-secondary);
    line-height: 1.6;
}

/* 健康生活方式 */
.lifestyle-grid {
    display: grid;
    gap: 20px;
}

@media (min-width: 640px) {
    .lifestyle-grid {
        grid-template-columns: repeat(2, 1fr);
    }
}

@media (min-width: 1024px) {
    .lifestyle-grid {
        grid-template-columns: repeat(3, 1fr);
    }
}

.lifestyle-item {
    text-align: center;
    padding: 32px 24px;
    background: var(--bg-secondary);
    border-radius: var(--radius-lg);
    box-shadow: var(--shadow-sm);
    transition: var(--transition);
    opacity: 0;
    transform: translateY(20px);
}

.lifestyle-item.visible {
    opacity: 1;
    transform: translateY(0);
}

.lifestyle-item:hover {
    transform: translateY(-4px);
    box-shadow: var(--shadow-md);
}

.lifestyle-img {
    font-size: 48px;
    margin-bottom: 16px;
}

.lifestyle-item h4 {
    font-size: 17px;
    font-weight: 600;
    margin-bottom: 8px;
}

.lifestyle-item p {
    font-size: 14px;
    color: var(--text-secondary);
}

/* ========================================
   研究数据
   ======================================== */
.section-research {
    background: var(--bg-secondary);
}

.research-content {
    display: flex;
    flex-direction: column;
    gap: 48px;
}

.research-image {
    border-radius: var(--radius-lg);
    overflow: hidden;
    box-shadow: var(--shadow-md);
}

.research-image img {
    width: 100%;
}

.research-stats {
    display: grid;
    grid-template-columns: repeat(2, 1fr);
    gap: 20px;
}

@media (min-width: 768px) {
    .research-stats {
        grid-template-columns: repeat(4, 1fr);
    }
}

.research-stat-item {
    text-align: center;
    padding: 24px;
    background: var(--bg-primary);
    border-radius: var(--radius-md);
    transition: var(--transition);
}

.research-stat-item:hover {
    transform: translateY(-4px);
    box-shadow: var(--shadow-sm);
}

.stat-icon {
    font-size: 32px;
    display: block;
    margin-bottom: 12px;
}

.stat-value {
    display: block;
    font-size: 28px;
    font-weight: 700;
    color: var(--accent);
}

.stat-desc {
    font-size: 13px;
    color: var(--text-secondary);
}

/* ========================================
   知识图谱
   ======================================== */
.knowledge-content {
    background: var(--bg-secondary);
    border-radius: var(--radius-lg);
    padding: 32px;
    box-shadow: var(--shadow-sm);
}

.knowledge-image {
    border-radius: var(--radius-md);
    overflow: hidden;
}

.knowledge-image img {
    width: 100%;
}

/* ========================================
   参考文献
   ======================================== */
.section-references {
    background: var(--bg-primary);
    padding-bottom: 48px;
}

.references-list {
    background: var(--bg-secondary);
    border-radius: var(--radius-lg);
    padding: 32px;
    box-shadow: var(--shadow-sm);
}

.reference-item {
    padding: 20px 0;
    border-bottom: 1px solid var(--border);
}

.reference-item:last-child {
    border-bottom: none;
}

.reference-number {
    display: inline-block;
    width: 28px;
    height: 28px;
    background: var(--accent);
    color: white;
    font-size: 13px;
    font-weight: 600;
    border-radius: 50%;
    text-align: center;
    line-height: 28px;
    margin-right: 12px;
}

.reference-title {
    font-size: 15px;
    font-weight: 600;
    color: var(--text-primary);
    margin-bottom: 4px;
}

.reference-meta {
    font-size: 13px;
    color: var(--text-secondary);
    margin-left: 40px;
}

.reference-doi {
    font-size: 12px;
    color: var(--accent);
    margin-left: 40px;
    margin-top: 4px;
}

/* ========================================
   页脚
   ======================================== */
.footer {
    background: var(--bg-dark);
    color: white;
    padding: 64px 0 32px;
}

.footer-content {
    display: grid;
    gap: 32px;
    margin-bottom: 48px;
}

@media (min-width: 768px) {
    .footer-content {
        grid-template-columns: 2fr 1fr 1fr;
    }
}

.footer h4 {
    font-size: 14px;
    font-weight: 600;
    margin-bottom: 16px;
    color: white;
}

.footer p, .footer li {
    font-size: 13px;
    color: #a1a1a6;
    line-height: 1.6;
}

.footer-links ul {
    list-style: none;
}

.footer-links li {
    margin-bottom: 8px;
}

.footer-links a {
    color: #a1a1a6;
    transition: var(--transition);
}

.footer-links a:hover {
    color: white;
}

.footer-bottom {
    padding-top: 32px;
    border-top: 1px solid #424245;
    text-align: center;
}

.footer-bottom p {
    margin-bottom: 8px;
}

.copyright {
    font-size: 12px;
    color: #6e6e73;
}

/* ========================================
   动画类
   ======================================== */
.fade-in {
    opacity: 0;
    transform: translateY(20px);
    transition: opacity 0.6s ease, transform 0.6s ease;
}

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

/* ========================================
   响应式调整
   ======================================== */
@media (max-width: 640px) {
    .section {
        padding: 60px 0;
    }

    .hero-stats {
        flex-direction: column;
        gap: 20px;
    }

    .quiz-form {
        grid-template-columns: 1fr;
    }

    .research-stats {
        grid-template-columns: repeat(2, 1fr);
    }
}

/* ========================================
   触摸优化
   ======================================== */
@media (hover: none) {
    .what-card:hover,
    .protection-card:hover,
    .effect-card:hover,
    .myth-card:hover,
    .lifestyle-item:hover,
    .path-item:hover {
        transform: none;
    }
}

/* ========================================
   减少动效偏好
   ======================================== */
@media (prefers-reduced-motion: reduce) {
    *,
    *::before,
    *::after {
        animation-duration: 0.01ms !important;
        animation-iteration-count: 1 !important;
        transition-duration: 0.01ms !important;
        scroll-behavior: auto !important;
    }
}