/* ============================================
   Dism++ 官方网站 - 主样式表
   ============================================ */

/* --- CSS Reset & Base --- */
*, *::before, *::after {
    margin: 0;
    padding: 0;
    box-sizing: border-box;
}

:root {
    --color-primary: #0078D4;
    --color-primary-dark: #005A9E;
    --color-primary-light: #E8F4FD;
    --color-accent: #FF6B35;
    --color-text: #1A1A1A;
    --color-text-secondary: #555;
    --color-text-muted: #888;
    --color-bg: #FFFFFF;
    --color-bg-alt: #F5F7FA;
    --color-bg-dark: #1E2A3A;
    --color-border: #E5E7EB;
    --color-success: #10B981;
    --font-sans: -apple-system, BlinkMacSystemFont, "Segoe UI", "PingFang SC", "Microsoft YaHei", "Hiragino Sans GB", "Helvetica Neue", Arial, sans-serif;
    --font-mono: "Cascadia Code", "Fira Code", "Consolas", "Monaco", monospace;
    --shadow-sm: 0 1px 3px rgba(0,0,0,0.08);
    --shadow-md: 0 4px 16px rgba(0,0,0,0.1);
    --shadow-lg: 0 12px 40px rgba(0,0,0,0.12);
    --radius: 8px;
    --radius-lg: 12px;
    --max-width: 1200px;
    --nav-height: 64px;
}

html {
    font-size: 16px;
    scroll-behavior: smooth;
    -webkit-font-smoothing: antialiased;
    -moz-osx-font-smoothing: grayscale;
}

body {
    font-family: var(--font-sans);
    color: var(--color-text);
    background: var(--color-bg);
    line-height: 1.7;
    min-height: 100vh;
    display: flex;
    flex-direction: column;
}

a {
    color: var(--color-primary);
    text-decoration: none;
    transition: color 0.2s;
}
a:hover { color: var(--color-primary-dark); }

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

ul { list-style: none; }

/* --- Navigation --- */
.navbar {
    position: sticky;
    top: 0;
    z-index: 1000;
    background: rgba(255,255,255,0.92);
    backdrop-filter: blur(12px);
    -webkit-backdrop-filter: blur(12px);
    border-bottom: 1px solid var(--color-border);
    height: var(--nav-height);
}

.nav-inner {
    max-width: var(--max-width);
    margin: 0 auto;
    padding: 0 24px;
    height: 100%;
    display: flex;
    align-items: center;
    justify-content: space-between;
}

.nav-logo {
    display: flex;
    align-items: center;
    gap: 10px;
    font-size: 1.35rem;
    font-weight: 700;
    color: var(--color-text);
}
.nav-logo .logo-icon {
    width: 38px;
    height: 38px;
    background: linear-gradient(135deg, var(--color-primary), #00B4D8);
    border-radius: 10px;
    display: flex;
    align-items: center;
    justify-content: center;
    color: #fff;
    font-weight: 800;
    font-size: 1.1rem;
}
.nav-logo span { color: var(--color-primary); }

.nav-links {
    display: flex;
    align-items: center;
    gap: 4px;
}
.nav-links a {
    display: block;
    padding: 8px 18px;
    color: var(--color-text-secondary);
    font-size: 0.95rem;
    font-weight: 500;
    border-radius: 6px;
    transition: all 0.2s;
}
.nav-links a:hover,
.nav-links a.active {
    color: var(--color-primary);
    background: var(--color-primary-light);
}
.nav-links a.btn-download-nav {
    color: #fff;
    background: var(--color-primary);
    margin-left: 8px;
    padding: 8px 22px;
    font-weight: 600;
}
.nav-links a.btn-download-nav:hover {
    background: var(--color-primary-dark);
    color: #fff;
}

.mobile-toggle {
    display: none;
    background: none;
    border: none;
    cursor: pointer;
    padding: 6px;
    flex-direction: column;
    gap: 5px;
}
.mobile-toggle span {
    display: block;
    width: 24px;
    height: 2px;
    background: var(--color-text);
    border-radius: 2px;
    transition: all 0.3s;
}

/* --- Hero Section --- */
.hero {
    background: linear-gradient(160deg, #F0F7FF 0%, #E8F4FD 30%, var(--color-bg-alt) 100%);
    padding: 80px 24px 100px;
    text-align: center;
    position: relative;
    overflow: hidden;
}
.hero::before {
    content: '';
    position: absolute;
    top: -200px;
    right: -200px;
    width: 600px;
    height: 600px;
    background: radial-gradient(circle, rgba(0,120,212,0.06) 0%, transparent 70%);
    border-radius: 50%;
}
.hero::after {
    content: '';
    position: absolute;
    bottom: -150px;
    left: -150px;
    width: 500px;
    height: 500px;
    background: radial-gradient(circle, rgba(0,120,212,0.04) 0%, transparent 70%);
    border-radius: 50%;
}

.hero-inner {
    max-width: 1200px;
    margin: 0 auto;
    position: relative;
    z-index: 1;
}

.hero-badge {
    display: inline-block;
    background: var(--color-primary-light);
    color: var(--color-primary);
    padding: 6px 18px;
    border-radius: 20px;
    font-size: 0.85rem;
    font-weight: 600;
    margin-bottom: 24px;
}

.hero h1 {
    font-size: 3rem;
    font-weight: 800;
    color: var(--color-text);
    line-height: 1.3;
    margin-bottom: 20px;
}
.hero h1 .highlight {
    background: linear-gradient(135deg, var(--color-primary), #00B4D8);
    -webkit-background-clip: text;
    -webkit-text-fill-color: transparent;
    background-clip: text;
}

.hero p {
    font-size: 1.15rem;
    color: var(--color-text-secondary);
    max-width: 600px;
    margin: 0 auto 36px;
    line-height: 1.8;
}

.hero-actions {
    display: flex;
    gap: 16px;
    justify-content: center;
    flex-wrap: wrap;
}

.btn {
    display: inline-flex;
    align-items: center;
    gap: 8px;
    padding: 14px 32px;
    font-size: 1rem;
    font-weight: 600;
    border-radius: var(--radius);
    border: none;
    cursor: pointer;
    transition: all 0.25s;
    text-decoration: none;
    font-family: var(--font-sans);
}
.btn-primary {
    background: var(--color-primary);
    color: #fff;
    box-shadow: 0 4px 14px rgba(0,120,212,0.35);
}
.btn-primary:hover {
    background: var(--color-primary-dark);
    color: #fff;
    transform: translateY(-1px);
    box-shadow: 0 6px 20px rgba(0,120,212,0.4);
}
.btn-secondary {
    background: #fff;
    color: var(--color-primary);
    border: 1.5px solid var(--color-primary);
}
.btn-secondary:hover {
    background: var(--color-primary-light);
    color: var(--color-primary-dark);
}

.hero-stats {
    display: flex;
    justify-content: center;
    gap: 60px;
    margin-top: 60px;
}
.hero-stat {
    text-align: center;
}
.hero-stat .number {
    font-size: 2rem;
    font-weight: 800;
    color: var(--color-primary);
}
.hero-stat .label {
    font-size: 0.9rem;
    color: var(--color-text-muted);
    margin-top: 4px;
}

/* --- Section Common --- */
.section {
    padding: 40px 24px;
}
.section-alt {
    background: var(--color-bg-alt);
}

.section-header {
    text-align: center;
    margin-bottom: 56px;
}
.section-header h2 {
    font-size: 2.2rem;
    font-weight: 700;
    color: var(--color-text);
    margin-bottom: 12px;
}
.section-header p {
    font-size: 1.05rem;
    color: var(--color-text-secondary);
    max-width: 560px;
    margin: 0 auto;
}
.section-inner {
    max-width: var(--max-width);
    margin: 0 auto;
}

/* --- Features Grid --- */
.features-grid {
    display: grid;
    grid-template-columns: repeat(3, 1fr);
    gap: 28px;
}

.feature-card {
    background: #fff;
    border: 1px solid var(--color-border);
    border-radius: var(--radius-lg);
    padding: 32px 28px;
    transition: all 0.3s;
    position: relative;
    overflow: hidden;
}
.feature-card:hover {
    transform: translateY(-4px);
    box-shadow: var(--shadow-md);
    border-color: var(--color-primary);
}
.feature-card::before {
    content: '';
    position: absolute;
    top: 0;
    left: 0;
    width: 100%;
    height: 3px;
    background: linear-gradient(90deg, var(--color-primary), #00B4D8);
    opacity: 0;
    transition: opacity 0.3s;
}
.feature-card:hover::before { opacity: 1; }

.feature-icon {
    width: 52px;
    height: 52px;
    border-radius: 12px;
    background: var(--color-primary-light);
    display: flex;
    align-items: center;
    justify-content: center;
    margin-bottom: 18px;
    font-size: 1.5rem;
}

.feature-card h3 {
    font-size: 1.15rem;
    font-weight: 700;
    margin-bottom: 10px;
    color: var(--color-text);
}
.feature-card p {
    font-size: 0.925rem;
    color: var(--color-text-secondary);
    line-height: 1.7;
}

/* --- Highlights --- */
.highlights-list {
    display: grid;
    grid-template-columns: repeat(2, 1fr);
    gap: 24px;
}

.highlight-item {
    display: flex;
    gap: 20px;
    padding: 28px;
    background: #fff;
    border-radius: var(--radius-lg);
    border: 1px solid var(--color-border);
    transition: box-shadow 0.3s;
}
.highlight-item:hover {
    box-shadow: var(--shadow-md);
}

.highlight-num {
    flex-shrink: 0;
    width: 44px;
    height: 44px;
    background: linear-gradient(135deg, var(--color-primary), #00B4D8);
    color: #fff;
    border-radius: 50%;
    display: flex;
    align-items: center;
    justify-content: center;
    font-weight: 800;
    font-size: 1.1rem;
}
.highlight-content h4 {
    font-size: 1.05rem;
    font-weight: 700;
    margin-bottom: 6px;
}
.highlight-content p {
    font-size: 0.9rem;
    color: var(--color-text-secondary);
    line-height: 1.6;
}

/* --- System Requirements --- */
.version-content {
    display: flex;
    gap: 32px;
    align-items: stretch;
    justify-content: center;
    flex-wrap: wrap;
}

.version-screenshot {
    flex: 1.6;
    min-width: 0;
    max-width: 600px;
    border-radius: var(--radius-lg);
    overflow: hidden;
    box-shadow: var(--shadow-md);
    border: 1px solid var(--color-border);
}

.version-screenshot img {
    display: block;
    width: 100%;
    height: 100%;
    object-fit: cover;
}

/* --- About 页面截图 --- */
.about-screenshot {
    max-width: 800px;
    margin: 0 auto 48px;
    border-radius: var(--radius-lg);
    overflow: hidden;
    box-shadow: var(--shadow-lg);
    border: 1px solid var(--color-border);
}
.about-screenshot img {
    display: block;
    width: 100%;
    height: auto;
}

.requirements-table {
    flex: 1;
	width: 100%;
    max-width: 700px;
    margin: 0 auto;
    border-collapse: collapse;
}
.requirements-table th,
.requirements-table td {
    padding: 14px 20px;
    text-align: left;
    border-bottom: 1px solid var(--color-border);
}
.requirements-table th {
    font-weight: 600;
    color: var(--color-text-secondary);
    font-size: 0.9rem;
    width: 100px;
    background: var(--color-bg-alt);
}
.requirements-table td {
    font-size: 0.95rem;
}
.requirements-table tr:last-child th,
.requirements-table tr:last-child td {
    border-bottom: none;
}

/* --- CTA Banner --- */
.cta-banner {
    background: linear-gradient(135deg, var(--color-primary), #005A9E);
    padding: 64px 24px;
    text-align: center;
    color: #fff;
}
.cta-banner h2 {
    font-size: 2rem;
    font-weight: 700;
    margin-bottom: 12px;
}
.cta-banner p {
    font-size: 1.05rem;
    opacity: 0.9;
    margin-bottom: 30px;
}
.cta-banner .btn {
    background: #fff;
    color: var(--color-primary);
    font-weight: 700;
}
.cta-banner .btn:hover {
    background: rgba(255,255,255,0.9);
    transform: translateY(-2px);
    box-shadow: 0 8px 24px rgba(0,0,0,0.2);
}

/* --- Download Page --- */
.download-hero {
    background: linear-gradient(160deg, #F0F7FF 0%, #E8F4FD 50%, var(--color-bg-alt) 100%);
    padding: 40px 24px 40px;
    text-align: center;
}
.download-hero h1 {
    font-size: 2.5rem;
    font-weight: 800;
    margin-bottom: 12px;
}
.download-hero p {
    color: var(--color-text-secondary);
    font-size: 1.05rem;
}

.version-tag {
    display: inline-block;
    background: var(--color-primary);
    color: #fff;
    padding: 6px 16px;
    border-radius: 20px;
    font-size: 0.9rem;
    font-weight: 600;
    margin-bottom: 16px;
}

.download-options {
    display: grid;
    grid-template-columns: repeat(3, 1fr);
    gap: 28px;
    margin-top: 32px;
}

.download-card {
    background: #fff;
    border: 2px solid var(--color-border);
    border-radius: var(--radius-lg);
    padding: 40px 28px;
    text-align: center;
    transition: all 0.3s;
}
.download-card:hover {
    border-color: var(--color-primary);
    box-shadow: var(--shadow-lg);
    transform: translateY(-4px);
}
.download-card.featured {
    border-color: var(--color-primary);
    position: relative;
}
.download-card.featured::before {
    content: '推荐';
    position: absolute;
    top: -12px;
    left: 50%;
    transform: translateX(-50%);
    background: var(--color-accent);
    color: #fff;
    padding: 4px 16px;
    border-radius: 12px;
    font-size: 0.8rem;
    font-weight: 700;
}

.download-icon {
    width: 64px;
    height: 64px;
    margin: 0 auto 20px;
    border-radius: 16px;
    display: flex;
    align-items: center;
    justify-content: center;
    font-size: 1.8rem;
}
.download-icon.quark { background: #E8F5FF; }
.download-icon.baidu { background: #EBF5FF; }
.download-icon.xunlei { background: #F0F8FF; }

.download-card h3 {
    font-size: 1.2rem;
    font-weight: 700;
    margin-bottom: 8px;
}
.download-card .file-info {
    font-size: 0.85rem;
    color: var(--color-text-muted);
    margin-bottom: 24px;
}

.download-card .btn {
    width: 100%;
    justify-content: center;
}

.download-note {
    text-align: center;
    margin-top: 24px;
    padding: 16px 24px;
    background: #FFF8E1;
    border-radius: var(--radius);
    font-size: 0.9rem;
    color: #8B6914;
    border: 1px solid #FFE082;
}

/* --- Instructions --- */
.instructions {
    display: grid;
    grid-template-columns: repeat(3, 1fr);
    gap: 32px;
    counter-reset: step;
}
.instruction-step {
    text-align: center;
    position: relative;
    padding-top: 50px;
}
.instruction-step::before {
    counter-increment: step;
    content: counter(step);
    position: absolute;
    top: 0;
    left: 50%;
    transform: translateX(-50%);
    width: 40px;
    height: 40px;
    background: var(--color-primary);
    color: #fff;
    border-radius: 50%;
    display: flex;
    align-items: center;
    justify-content: center;
    font-weight: 800;
    font-size: 1.1rem;
}
.instruction-step h4 {
    font-size: 1.05rem;
    font-weight: 700;
    margin-bottom: 8px;
}
.instruction-step p {
    font-size: 0.9rem;
    color: var(--color-text-secondary);
    line-height: 1.6;
}

/* --- FAQ --- */
.faq-list {
    max-width: 760px;
    margin: 0 auto;
}
.faq-item {
    border: 1px solid var(--color-border);
    border-radius: var(--radius);
    margin-bottom: 12px;
    overflow: hidden;
    background: #fff;
}
.faq-q {
    padding: 18px 24px;
    font-weight: 600;
    font-size: 0.95rem;
    cursor: pointer;
    display: flex;
    justify-content: space-between;
    align-items: center;
    user-select: none;
    color: var(--color-text);
    transition: background 0.2s;
}
.faq-q:hover { background: var(--color-bg-alt); }
.faq-q .arrow {
    font-size: 0.75rem;
    transition: transform 0.3s;
    color: var(--color-text-muted);
}
.faq-item.open .faq-q .arrow { transform: rotate(180deg); }
.faq-a {
    max-height: 0;
    overflow: hidden;
    transition: max-height 0.35s ease, padding 0.35s ease;
    padding: 0 24px;
    font-size: 0.9rem;
    color: var(--color-text-secondary);
    line-height: 1.7;
}
.faq-item.open .faq-a {
    max-height: 300px;
    padding: 0 24px 20px;
}

/* --- Breadcrumb --- */
.breadcrumb {
    max-width: var(--max-width);
    margin: 0 auto;
    padding: 16px 24px 0;
    font-size: 0.85rem;
    color: var(--color-text-muted);
}
.breadcrumb a { color: var(--color-text-muted); }
.breadcrumb a:hover { color: var(--color-primary); }
.breadcrumb .sep { margin: 0 6px; }

/* --- Footer --- */
.footer {
    background: var(--color-bg-dark);
    color: rgba(255,255,255,0.7);
    padding: 48px 24px 32px;
    margin-top: auto;
}
.footer-inner {
    max-width: var(--max-width);
    margin: 0 auto;
    display: grid;
    grid-template-columns: 2fr 1fr 1fr;
    gap: 40px;
}
.footer-brand h3 {
    color: #fff;
    font-size: 1.2rem;
    margin-bottom: 10px;
}
.footer-brand p {
    font-size: 0.85rem;
    line-height: 1.7;
}
.footer-col h4 {
    color: #fff;
    font-size: 1rem;
    margin-bottom: 14px;
}
.footer-col a {
    display: block;
    color: rgba(255,255,255,0.6);
    font-size: 0.85rem;
    margin-bottom: 8px;
    transition: color 0.2s;
}
.footer-col a:hover { color: #fff; }
.footer-bottom {
    max-width: var(--max-width);
    margin: 32px auto 0;
    padding-top: 20px;
    border-top: 1px solid rgba(255,255,255,0.1);
    text-align: center;
    font-size: 0.8rem;
    color: rgba(255,255,255,0.4);
}

/* --- Responsive --- */
@media (max-width: 1024px) {
    .features-grid { grid-template-columns: repeat(2, 1fr); }
    .download-options { grid-template-columns: 1fr; max-width: 420px; margin-left: auto; margin-right: auto; }
    .instructions { grid-template-columns: 1fr; gap: 24px; }
}

@media (max-width: 900px) {
    .version-content {
        flex-direction: column;
        align-items: center;
        gap: 24px;
    }
    
    .version-screenshot {
        max-width: 100%;
        width: 100%;
    }
    
    .requirements-table {
        max-width: 100%;
    }
}

@media (max-width: 768px) {
    :root { --nav-height: 56px; }

    .mobile-toggle { display: flex; }

    .nav-links {
        position: fixed;
        top: var(--nav-height);
        left: 0;
        right: 0;
        background: #fff;
        flex-direction: column;
        padding: 16px 24px;
        border-bottom: 1px solid var(--color-border);
        box-shadow: var(--shadow-md);
        transform: translateY(-120%);
        transition: transform 0.3s ease;
        z-index: 999;
    }
    .nav-links.open { transform: translateY(0); }
    .nav-links a { padding: 12px 18px; }
    .nav-links a.btn-download-nav { margin-left: 0; }

    .hero { padding: 56px 20px 64px; }
    .hero h1 { font-size: 2rem; }
    .hero p { font-size: 1rem; }
    .hero-stats { gap: 30px; flex-wrap: wrap; }
    .hero-stat .number { font-size: 1.5rem; }

    .section { padding: 48px 20px; }
    .section-header h2 { font-size: 1.6rem; }

    .features-grid { grid-template-columns: 1fr; }
    .highlights-list { grid-template-columns: 1fr; }

    .footer-inner { grid-template-columns: 1fr; gap: 28px; }
    .cta-banner h2 { font-size: 1.5rem; }

    .download-hero h1 { font-size: 1.8rem; }
    .download-options { max-width: 100%; }
}

/* --- Utility --- */
.text-center { text-align: center; }
.mt-20 { margin-top: 20px; }
.mt-40 { margin-top: 40px; }

/* ============================================
   页面通用样式（帮助中心 / 版本说明 / 教程 / 关于）
   ============================================ */

/* --- Page Hero --- */
.page-hero {
    background: linear-gradient(160deg, #F0F7FF 0%, #E8F4FD 50%, var(--color-bg-alt) 100%);
    padding: 56px 24px 40px;
    text-align: center;
}
.page-hero h1 {
    font-size: 2.2rem;
    font-weight: 800;
    margin-bottom: 10px;
}
.page-hero p {
    font-size: 1rem;
    color: var(--color-text-secondary);
    max-width: 560px;
    margin: 0 auto;
}

/* --- Sidebar Layout (帮助中心) --- */
.help-layout {
    display: grid;
    grid-template-columns: 260px 1fr;
    gap: 36px;
    align-items: start;
}

.help-sidebar {
    position: sticky;
    top: calc(var(--nav-height) + 24px);
    background: #fff;
    border: 1px solid var(--color-border);
    border-radius: var(--radius-lg);
    padding: 8px 0;
    overflow: hidden;
}

.help-sidebar-title {
    font-size: 0.8rem;
    font-weight: 700;
    color: var(--color-text-muted);
    text-transform: uppercase;
    letter-spacing: 0.5px;
    padding: 12px 20px 8px;
}

.help-sidebar a {
    display: flex;
    align-items: center;
    gap: 10px;
    padding: 10px 20px;
    font-size: 0.9rem;
    color: var(--color-text-secondary);
    font-weight: 500;
    transition: all 0.15s;
    border-left: 3px solid transparent;
}
.help-sidebar a:hover,
.help-sidebar a.active {
    color: var(--color-primary);
    background: var(--color-primary-light);
    border-left-color: var(--color-primary);
}

.help-content h2 {
    font-size: 1.5rem;
    font-weight: 700;
    margin-bottom: 16px;
    padding-bottom: 10px;
    border-bottom: 2px solid var(--color-border);
}
.help-content h3 {
    font-size: 1.1rem;
    font-weight: 700;
    margin: 28px 0 10px;
    color: var(--color-text);
}
.help-content h3:first-of-type { margin-top: 0; }
.help-content p {
    font-size: 0.95rem;
    color: var(--color-text-secondary);
    line-height: 1.8;
    margin-bottom: 14px;
}
.help-content ul {
    margin: 0 0 16px 20px;
    list-style: disc;
}
.help-content ul li {
    font-size: 0.95rem;
    color: var(--color-text-secondary);
    line-height: 1.8;
    margin-bottom: 4px;
}
.help-content .help-tip {
    background: #EBF8FF;
    border: 1px solid #BEE3F8;
    border-radius: var(--radius);
    padding: 14px 18px;
    margin: 16px 0;
    font-size: 0.9rem;
    color: #2B6CB0;
    line-height: 1.7;
}
.help-content .help-warning {
    background: #FFF5F5;
    border: 1px solid #FED7D7;
    border-radius: var(--radius);
    padding: 14px 18px;
    margin: 16px 0;
    font-size: 0.9rem;
    color: #C53030;
    line-height: 1.7;
}

/* --- Timeline (版本说明) --- */
.timeline {
    position: relative;
    padding-left: 40px;
}
.timeline::before {
    content: '';
    position: absolute;
    left: 15px;
    top: 0;
    bottom: 0;
    width: 2px;
    background: var(--color-border);
}

.timeline-item {
    position: relative;
    margin-bottom: 36px;
    padding-bottom: 0;
}
.timeline-item::before {
    content: '';
    position: absolute;
    left: -33px;
    top: 4px;
    width: 12px;
    height: 12px;
    background: var(--color-primary);
    border-radius: 50%;
    border: 3px solid #fff;
    box-shadow: 0 0 0 2px var(--color-primary);
}
.timeline-item:last-child { margin-bottom: 0; }

.timeline-version {
    display: inline-block;
    background: var(--color-primary);
    color: #fff;
    padding: 4px 14px;
    border-radius: 14px;
    font-size: 0.85rem;
    font-weight: 700;
    margin-bottom: 6px;
}
.timeline-date {
    font-size: 0.85rem;
    color: var(--color-text-muted);
    margin-bottom: 12px;
    display: block;
}
.timeline-body {
    background: #fff;
    border: 1px solid var(--color-border);
    border-radius: var(--radius);
    padding: 20px 24px;
}
.timeline-body h3 {
    font-size: 1rem;
    font-weight: 700;
    margin-bottom: 10px;
}
.timeline-body ul {
    margin-left: 18px;
    list-style: disc;
}
.timeline-body ul li {
    font-size: 0.9rem;
    color: var(--color-text-secondary);
    line-height: 1.7;
    margin-bottom: 3px;
}

/* --- Tutorial Grid (使用教程) --- */
.tutorial-grid {
    display: grid;
    grid-template-columns: repeat(2, 1fr);
    gap: 24px;
}

.tutorial-card {
    background: #fff;
    border: 1px solid var(--color-border);
    border-radius: var(--radius-lg);
    overflow: hidden;
    transition: all 0.3s;
    cursor: pointer;
    display: block;
    color: inherit;
    text-decoration: none;
}
.tutorial-card:hover {
    transform: translateY(-4px);
    box-shadow: var(--shadow-md);
    border-color: var(--color-primary);
}

.tutorial-card-header {
    padding: 24px 24px 0;
}
.tutorial-step-badge {
    display: inline-block;
    background: var(--color-primary-light);
    color: var(--color-primary);
    padding: 4px 12px;
    border-radius: 12px;
    font-size: 0.78rem;
    font-weight: 700;
    margin-bottom: 10px;
}
.tutorial-card-header h3 {
    font-size: 1.1rem;
    font-weight: 700;
    margin-bottom: 6px;
    color: var(--color-text);
}
.tutorial-card-header p {
    font-size: 0.9rem;
    color: var(--color-text-secondary);
    line-height: 1.6;
}

.tutorial-card-body {
    padding: 6px 24px 24px;
    border-top: 1px solid var(--color-border);
    margin-top: 16px;
}
.tutorial-card-body ol {
    margin-left: 18px;
    counter-reset: tut-step;
}
.tutorial-card-body ol li {
    font-size: 0.88rem;
    color: var(--color-text-secondary);
    line-height: 1.7;
    margin-bottom: 4px;
    padding-left: 4px;
}

/* --- About Page --- */
.about-grid {
    display: grid;
    grid-template-columns: repeat(2, 1fr);
    gap: 28px;
}

.about-card {
    background: #fff;
    border: 1px solid var(--color-border);
    border-radius: var(--radius-lg);
    padding: 32px;
    transition: box-shadow 0.3s;
}
.about-card:hover { box-shadow: var(--shadow-md); }

.about-card h3 {
    font-size: 1.15rem;
    font-weight: 700;
    margin-bottom: 12px;
}
.about-card p {
    font-size: 0.92rem;
    color: var(--color-text-secondary);
    line-height: 1.7;
}
.about-card .about-icon {
    font-size: 2rem;
    margin-bottom: 14px;
}

/* --- Back to Top --- */
.back-to-top {
    position: fixed;
    bottom: 32px;
    right: 32px;
    width: 44px;
    height: 44px;
    background: var(--color-primary);
    color: #fff;
    border: none;
    border-radius: 50%;
    cursor: pointer;
    font-size: 1.2rem;
    display: flex;
    align-items: center;
    justify-content: center;
    box-shadow: var(--shadow-md);
    opacity: 0;
    visibility: hidden;
    transition: all 0.3s;
    z-index: 900;
}
.back-to-top.show {
    opacity: 1;
    visibility: visible;
}
.back-to-top:hover {
    background: var(--color-primary-dark);
    transform: translateY(-2px);
}

/* --- Responsive for new pages --- */
@media (max-width: 768px) {
    .help-layout {
        grid-template-columns: 1fr;
    }
    .help-sidebar {
        position: static;
        display: flex;
        flex-wrap: wrap;
        gap: 0;
        padding: 8px;
        border-radius: var(--radius);
    }
    .help-sidebar a {
        font-size: 0.82rem;
        padding: 8px 14px;
        border-left: none;
        border-radius: 6px;
    }
    .help-sidebar-title { display: none; }

    .tutorial-grid { grid-template-columns: 1fr; }
    .about-grid { grid-template-columns: 1fr; }

    .timeline { padding-left: 30px; }
    .timeline-item::before { left: -23px; }

    .page-hero h1 { font-size: 1.7rem; }
}


/* --- Scrollbar --- */
::-webkit-scrollbar { width: 8px; }
::-webkit-scrollbar-track { background: var(--color-bg-alt); }
::-webkit-scrollbar-thumb { background: #C0C4CC; border-radius: 4px; }
::-webkit-scrollbar-thumb:hover { background: #909399; }