:root {
    --primary-cool: #4f46e5;
    --secondary-cool: #06b6d4;
    --bg-cool: #f8fafc;
    --surface-cool: #ffffff;
    --text-cool-main: #0f172a;
    --text-cool-muted: #64748b;
    --border-cool: #e2e8f0;
    --footer-bg: #f1f5f9;
    --paper-white: #fdfdfd;
    --shadow-sm: 0 4px 12px rgba(15, 23, 42, 0.04);
    --shadow-md: 0 20px 40px -15px rgba(15, 23, 42, 0.06);
    --shadow-lg: 0 20px 40px -15px rgba(15, 23, 42, 0.3);
    --radius-lg: 24px;
    --radius-md: 16px;
    --radius-sm: 12px;
    --transition: all 0.2s ease;
}

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

body {
    font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, "Helvetica Neue", sans-serif;
    color: var(--text-cool-main);
    background-color: var(--bg-cool);
    line-height: 1.7;
    -webkit-font-smoothing: antialiased;
}

/* ===== 头部导航 ===== */
header {
    border-bottom: 1px solid var(--border-cool);
    position: sticky;
    top: 0;
    background: rgba(255, 255, 255, 0.85);
    backdrop-filter: blur(20px);
    -webkit-backdrop-filter: blur(20px);
    z-index: 100;
}

.nav-container {
    max-width: 1200px;
    margin: 0 auto;
    display: flex;
    justify-content: space-between;
    align-items: center;
    padding: 16px 20px;
}

.logo a {
    display: flex;
    align-items: center;
    gap: 10px;
    font-size: 22px;
    font-weight: 800;
    color: var(--text-cool-main);
    text-decoration: none;
    letter-spacing: -0.5px;
}

.logo svg {
    width: 32px;
    height: 32px;
    fill: none;
    stroke: var(--primary-cool);
    color: var(--primary-cool);
}

.nav-links a {
    color: var(--text-cool-muted);
    text-decoration: none;
    margin-left: 20px;
    font-size: 15px;
    font-weight: 600;
    transition: var(--transition);
    padding: 8px 16px;
    border-radius: 20px;
}

.nav-links a:hover {
    color: var(--primary-cool);
    background: rgba(79, 70, 229, 0.04);
}

.nav-links a.active-cool {
    color: var(--primary-cool);
    background: rgba(79, 70, 229, 0.08);
}

/* ===== 主视觉区 ===== */
.hero-layout-b {
    max-width: 1200px;
    margin: 0 auto;
    padding: 80px 20px 40px;
    text-align: center;
}

.hero-layout-b h1 {
    font-size: 48px;
    color: var(--text-cool-main);
    font-weight: 800;
    letter-spacing: -1px;
    line-height: 1.2;
    margin-bottom: 20px;
}

.hero-layout-b h1 span {
    background: linear-gradient(135deg, var(--primary-cool) 0%, var(--secondary-cool) 80%);
    -webkit-background-clip: text;
    background-clip: text;
    -webkit-text-fill-color: transparent;
}

.hero-layout-b p {
    font-size: 18px;
    color: var(--text-cool-muted);
    max-width: 700px;
    margin: 0 auto 40px;
}

/* ===== 下载与视频网格 ===== */
.grid-action-panel {
    max-width: 1200px;
    margin: 0 auto 60px;
    padding: 0 20px;
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(320px, 1fr));
    gap: 30px;
}

.video-wrapper-cool {
    background: var(--surface-cool);
    border: 1px solid var(--border-cool);
    border-radius: var(--radius-lg);
    padding: 16px;
    box-shadow: var(--shadow-md);
}

.video-container {
    width: 100%;
    aspect-ratio: 16 / 9;
    border-radius: var(--radius-md);
    overflow: hidden;
}

.video-container iframe {
    width: 100%;
    height: 100%;
    border: none;
}

.quick-download-card {
    background: linear-gradient(145deg, #0f172a 0%, #1e293b 100%);
    border-radius: var(--radius-lg);
    padding: 40px 30px;
    color: #ffffff;
    display: flex;
    flex-direction: column;
    justify-content: center;
    box-shadow: var(--shadow-lg);
}

.quick-download-card h3 {
    font-size: 22px;
    font-weight: 700;
    margin-bottom: 12px;
    letter-spacing: -0.5px;
}

.quick-download-card p {
    font-size: 14px;
    color: #94a3b8;
    margin-bottom: 30px;
    line-height: 1.6;
}

.btn-cool-primary {
    display: block;
    background: #ffffff;
    color: #0f172a;
    text-decoration: none;
    text-align: center;
    padding: 14px 20px;
    border-radius: var(--radius-sm);
    font-weight: 700;
    font-size: 15px;
    margin-bottom: 12px;
    transition: var(--transition);
}

.btn-cool-primary:hover {
    background: #f1f5f9;
    transform: translateY(-2px);
    box-shadow: 0 8px 20px rgba(0,0,0,0.15);
}

.btn-cool-secondary {
    display: block;
    background: rgba(255, 255, 255, 0.08);
    color: #ffffff;
    text-decoration: none;
    text-align: center;
    padding: 14px 20px;
    border-radius: var(--radius-sm);
    font-weight: 600;
    font-size: 14px;
    border: 1px solid rgba(255, 255, 255, 0.1);
    transition: var(--transition);
}

.btn-cool-secondary:hover {
    background: rgba(255, 255, 255, 0.15);
    border-color: rgba(255, 255, 255, 0.25);
}

/* ===== 折纸工坊 - 三步折叠法 ===== */
.origami-workshop {
    max-width: 1200px;
    margin: 80px auto;
    padding: 0 20px;
}

.workshop-inner {
    background: var(--surface-cool);
    border: 1px solid var(--border-cool);
    border-radius: var(--radius-lg);
    padding: 50px 40px;
    box-shadow: var(--shadow-sm);
}

.workshop-subtitle {
    font-size: 16px;
    color: var(--text-cool-muted);
    margin-bottom: 40px;
    max-width: 600px;
}

.fold-steps {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(220px, 1fr));
    gap: 30px;
}

.fold-card {
    text-align: center;
    padding: 30px 20px;
    border-radius: var(--radius-md);
    background: var(--bg-cool);
    border: 1px solid transparent;
    transition: var(--transition);
    position: relative;
}

.fold-card:hover {
    border-color: var(--border-cool);
    background: var(--surface-cool);
    box-shadow: var(--shadow-md);
    transform: translateY(-4px);
}

.fold-number {
    font-size: 42px;
    font-weight: 900;
    color: rgba(79, 70, 229, 0.08);
    position: absolute;
    top: 10px;
    right: 20px;
    line-height: 1;
    pointer-events: none;
}

.fold-icon {
    width: 48px;
    height: 48px;
    margin: 0 auto 16px;
    color: var(--primary-cool);
}

.fold-icon svg {
    width: 100%;
    height: 100%;
}

.fold-card h4 {
    font-size: 17px;
    font-weight: 700;
    color: var(--text-cool-main);
    margin-bottom: 8px;
}

.fold-card p {
    font-size: 14px;
    color: var(--text-cool-muted);
    line-height: 1.6;
}

/* ===== 通用面板标题 ===== */
.panel-heading {
    font-size: 28px;
    font-weight: 800;
    color: var(--text-cool-main);
    margin-bottom: 40px;
    letter-spacing: -0.5px;
    display: flex;
    align-items: center;
    gap: 12px;
}

.panel-heading::before {
    content: '';
    width: 6px;
    height: 24px;
    background: var(--primary-cool);
    border-radius: 3px;
    flex-shrink: 0;
}

/* ===== 飞行航迹日志 ===== */
.timeline-section {
    max-width: 1200px;
    margin: 80px auto;
    padding: 0 20px;
}

.timeline-hub {
    position: relative;
    padding-left: 32px;
}

.timeline-hub::before {
    content: '';
    position: absolute;
    left: 6px;
    top: 10px;
    bottom: 10px;
    width: 2px;
    background: linear-gradient(to bottom, var(--primary-cool), var(--secondary-cool), var(--border-cool));
    border-radius: 1px;
}

.timeline-node {
    position: relative;
    margin-bottom: 45px;
}

.timeline-node::before {
    content: '';
    position: absolute;
    left: -32px;
    top: 6px;
    width: 14px;
    height: 14px;
    border-radius: 50%;
    background: var(--surface-cool);
    border: 3px solid var(--primary-cool);
    box-sizing: border-box;
    z-index: 2;
}

.timeline-time {
    font-size: 13px;
    font-weight: 700;
    color: var(--primary-cool);
    margin-bottom: 6px;
    letter-spacing: 0.5px;
    text-transform: uppercase;
}

.timeline-body {
    background: var(--surface-cool);
    border: 1px solid var(--border-cool);
    border-radius: var(--radius-md);
    padding: 24px 30px;
    box-shadow: var(--shadow-sm);
    transition: var(--transition);
}

.timeline-body:hover {
    border-color: var(--primary-cool);
    box-shadow: var(--shadow-md);
}

.timeline-body h4 {
    font-size: 18px;
    color: var(--text-cool-main);
    margin-bottom: 8px;
    font-weight: 700;
}

.timeline-body p {
    font-size: 15px;
    color: var(--text-cool-muted);
}

/* ===== 云端航线看板 ===== */
.matrix-section {
    max-width: 1200px;
    margin: 80px auto;
    padding: 0 20px;
}

.matrix-container {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(320px, 1fr));
    gap: 40px;
    align-items: center;
}

.matrix-info-text h3 {
    font-size: 26px;
    font-weight: 800;
    margin-bottom: 16px;
    letter-spacing: -0.5px;
    line-height: 1.3;
}

.matrix-info-text p {
    font-size: 16px;
    color: var(--text-cool-muted);
    margin-bottom: 24px;
    line-height: 1.7;
}

.matrix-stats-grid {
    display: grid;
    grid-template-columns: 1fr 1fr;
    gap: 20px;
}

.matrix-stat-item {
    background: var(--surface-cool);
    border: 1px solid var(--border-cool);
    padding: 24px;
    border-radius: var(--radius-md);
    transition: var(--transition);
}

.matrix-stat-item:hover {
    border-color: var(--secondary-cool);
    box-shadow: var(--shadow-md);
}

.matrix-stat-item div {
    font-size: 32px;
    font-weight: 800;
    color: var(--primary-cool);
    margin-bottom: 4px;
    letter-spacing: -1px;
    line-height: 1.1;
}

.matrix-stat-item span {
    font-size: 14px;
    font-weight: 600;
    color: var(--text-cool-main);
}

.matrix-stat-item p {
    font-size: 13px;
    color: var(--text-cool-muted);
    margin-top: 4px;
    margin-bottom: 0;
    line-height: 1.4;
}

.image-placeholder-matrix {
    width: 100%;
    min-height: 280px;
    background: linear-gradient(135deg, #f8fafc 0%, #eef2ff 100%);
    border-radius: 20px;
    display: flex;
    flex-direction: column;
    align-items: center;
    justify-content: center;
    color: var(--text-cool-muted);
    font-size: 14px;
    font-weight: 600;
    padding: 40px;
    border: 1px dashed var(--border-cool);
    gap: 16px;
}

.skyway-art {
    width: 100%;
    max-width: 280px;
    height: auto;
    opacity: 0.8;
}

/* ===== 纸飞机进化博物馆 ===== */
.history-sandbox {
    background: var(--surface-cool);
    border-top: 1px solid var(--border-cool);
    border-bottom: 1px solid var(--border-cool);
    padding: 80px 20px;
}

.sandbox-inner {
    max-width: 1200px;
    margin: 0 auto;
}

.sandbox-showcase {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(240px, 1fr));
    gap: 24px;
}

.sandbox-block {
    border-left: 3px solid var(--border-cool);
    padding-left: 20px;
    transition: var(--transition);
    cursor: default;
}

.sandbox-block:hover {
    border-left-color: var(--secondary-cool);
    transform: translateX(4px);
}

.sandbox-block h5 {
    font-size: 16px;
    font-weight: 700;
    color: var(--text-cool-main);
    margin-bottom: 10px;
}

.sandbox-block p {
    font-size: 14px;
    color: var(--text-cool-muted);
    line-height: 1.7;
}

/* ===== 常见折叠问题速查 ===== */
.faq-teaser {
    max-width: 1200px;
    margin: 80px auto;
    padding: 0 20px;
}

.faq-teaser-inner {
    background: var(--surface-cool);
    border: 1px solid var(--border-cool);
    border-radius: var(--radius-lg);
    padding: 50px 40px;
    box-shadow: var(--shadow-sm);
}

.faq-grid-mini {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(280px, 1fr));
    gap: 16px;
    margin-bottom: 30px;
}

.faq-item-mini {
    border: 1px solid var(--border-cool);
    border-radius: var(--radius-sm);
    overflow: hidden;
    transition: var(--transition);
}

.faq-item-mini:hover {
    border-color: var(--primary-cool);
}

.faq-item-mini summary {
    padding: 18px 20px;
    font-weight: 700;
    font-size: 15px;
    color: var(--text-cool-main);
    cursor: pointer;
    list-style: none;
    display: flex;
    justify-content: space-between;
    align-items: center;
    background: var(--bg-cool);
    transition: var(--transition);
}

.faq-item-mini summary::-webkit-details-marker {
    display: none;
}

.faq-item-mini summary::after {
    content: '+';
    font-size: 20px;
    color: var(--primary-cool);
    font-weight: 400;
    transition: transform 0.2s;
}

.faq-item-mini[open] summary::after {
    content: '−';
    transform: rotate(180deg);
}

.faq-item-mini[open] summary {
    background: var(--surface-cool);
    color: var(--primary-cool);
}

.faq-item-mini p {
    padding: 0 20px 18px;
    font-size: 14px;
    color: var(--text-cool-muted);
    line-height: 1.6;
}

.faq-more-link {
    display: inline-flex;
    align-items: center;
    gap: 6px;
    font-weight: 700;
    font-size: 15px;
    color: var(--primary-cool);
    text-decoration: none;
    transition: var(--transition);
}

.faq-more-link:hover {
    gap: 12px;
    color: var(--secondary-cool);
}

/* ===== 页脚 ===== */
.new-footer-cool {
    background-color: var(--footer-bg);
    border-top: 1px solid var(--border-cool);
    padding: 80px 20px 40px;
    color: var(--text-cool-main);
}

.footer-premium-layout {
    max-width: 1200px;
    margin: 0 auto;
    display: grid;
    grid-template-columns: 1fr 1.5fr;
    gap: 60px;
    padding-bottom: 50px;
    border-bottom: 1px solid var(--border-cool);
}

.footer-brand-side h4 {
    font-size: 20px;
    font-weight: 800;
    margin-bottom: 12px;
    color: var(--text-cool-main);
}

.footer-brand-side p {
    font-size: 14px;
    color: var(--text-cool-muted);
    margin-bottom: 24px;
    max-width: 380px;
    line-height: 1.7;
}

.footer-status-tag {
    display: inline-flex;
    align-items: center;
    gap: 8px;
    background: var(--surface-cool);
    border: 1px solid var(--border-cool);
    padding: 6px 14px;
    border-radius: 6px;
    font-size: 12px;
    color: #10b981;
    font-weight: 700;
}

.footer-status-tag::before {
    content: '';
    width: 6px;
    height: 6px;
    background: #10b981;
    border-radius: 50%;
    animation: pulse-dot 2s infinite;
}

@keyframes pulse-dot {
    0%, 100% { opacity: 1; }
    50% { opacity: 0.4; }
}

.footer-links-side {
    display: grid;
    grid-template-columns: repeat(3, 1fr);
    gap: 20px;
}

.footer-nav-col h5 {
    font-size: 14px;
    font-weight: 700;
    text-transform: uppercase;
    color: var(--text-cool-main);
    margin-bottom: 16px;
    letter-spacing: 0.5px;
}

.footer-nav-col ul {
    list-style: none;
}

.footer-nav-col ul li {
    margin-bottom: 10px;
}

.footer-nav-col ul li a {
    font-size: 14px;
    color: var(--text-cool-muted);
    text-decoration: none;
    transition: color 0.15s;
}

.footer-nav-col ul li a:hover {
    color: var(--primary-cool);
}

.footer-bottom-bar {
    max-width: 1200px;
    margin: 40px auto 0;
    display: flex;
    justify-content: space-between;
    align-items: center;
    font-size: 13px;
    color: var(--text-cool-muted);
    flex-wrap: wrap;
    gap: 15px;
}

.github-sha-badge {
    font-family: 'SF Mono', 'Cascadia Code', monospace;
    background: var(--surface-cool);
    padding: 4px 12px;
    border-radius: 4px;
    border: 1px solid var(--border-cool);
    color: var(--text-cool-main);
    font-size: 12px;
}

/* ===== 响应式设计 ===== */
@media (max-width: 992px) {
    .footer-premium-layout {
        grid-template-columns: 1fr;
        gap: 40px;
    }

    .hero-layout-b h1 {
        font-size: 36px;
    }

    .workshop-inner {
        padding: 40px 28px;
    }

    .faq-teaser-inner {
        padding: 40px 28px;
    }
}

@media (max-width: 768px) {
    .footer-links-side {
        grid-template-columns: 1fr;
        gap: 30px;
    }

    .footer-bottom-bar {
        flex-direction: column;
        text-align: center;
    }

    .nav-links {
        display: none;
    }

    .hero-layout-b h1 {
        font-size: 28px;
    }

    .grid-action-panel {
        grid-template-columns: 1fr;
    }

    .matrix-stats-grid {
        grid-template-columns: 1fr;
    }

    .sandbox-showcase {
        grid-template-columns: 1fr;
    }

    .fold-steps {
        grid-template-columns: 1fr;
    }

    .faq-grid-mini {
        grid-template-columns: 1fr;
    }

    .panel-heading {
        font-size: 22px;
    }

    .timeline-body {
        padding: 18px 20px;
    }
}

@media (max-width: 480px) {
    .quick-download-card {
        padding: 28px 20px;
    }

    .hero-layout-b {
        padding: 60px 16px 30px;
    }

    .workshop-inner,
    .faq-teaser-inner {
        padding: 30px 18px;
    }
}

/* ===== 减少动画偏好 ===== */
@media (prefers-reduced-motion: reduce) {
    .fold-card:hover,
    .btn-cool-primary:hover,
    .sandbox-block:hover {
        transform: none;
    }

    .footer-status-tag::before {
        animation: none;
    }

    * {
        transition-duration: 0.01ms !important;
    }
}