/* ===== CSS Variables ===== */
:root {
    --primary: #1565C0;
    --primary-dark: #0D47A1;
    --primary-light: #42A5F5;
    --primary-bg: #E3F2FD;
    --accent: #00C853;
    --accent-dark: #00A844;
    --warning: #FF9800;
    --error: #E53935;
    --info: #039BE5;

    --bg: #FFFFFF;
    --bg-alt: #F5F7FA;
    --bg-dark: #0B1120;
    --surface: #FFFFFF;
    --surface-hover: #F0F4F8;
    --border: #E2E8F0;

    --text: #1A202C;
    --text-secondary: #4A5568;
    --text-muted: #718096;
    --text-on-primary: #FFFFFF;

    --radius: 12px;
    --radius-sm: 8px;
    --radius-lg: 20px;
    --shadow: 0 1px 3px rgba(0,0,0,0.08), 0 4px 12px rgba(0,0,0,0.04);
    --shadow-lg: 0 4px 20px rgba(0,0,0,0.08), 0 8px 32px rgba(0,0,0,0.04);
    --shadow-xl: 0 8px 40px rgba(0,0,0,0.12);

    --font: 'Inter', -apple-system, BlinkMacSystemFont, 'Segoe UI', sans-serif;
    --transition: 0.3s cubic-bezier(0.4, 0, 0.2, 1);
}

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

html {
    scroll-behavior: smooth;
    font-size: 16px;
}

body {
    font-family: var(--font);
    color: var(--text);
    background: var(--bg);
    line-height: 1.7;
    -webkit-font-smoothing: antialiased;
}

img { max-width: 100%; }
a { text-decoration: none; color: inherit; }

/* ===== Container ===== */
.container {
    max-width: 1100px;
    margin: 0 auto;
    padding: 0 1.5rem;
}

/* ===== Navbar ===== */
.navbar {
    position: fixed;
    top: 0;
    left: 0;
    right: 0;
    z-index: 1000;
    background: rgba(255,255,255,0.85);
    backdrop-filter: blur(16px);
    -webkit-backdrop-filter: blur(16px);
    border-bottom: 1px solid transparent;
    transition: var(--transition);
}

.navbar.scrolled {
    border-bottom-color: var(--border);
    box-shadow: 0 1px 8px rgba(0,0,0,0.06);
}

.nav-container {
    max-width: 1100px;
    margin: 0 auto;
    padding: 0 1.5rem;
    display: flex;
    align-items: center;
    justify-content: space-between;
    height: 64px;
}

.nav-logo {
    display: flex;
    align-items: center;
    gap: 0.5rem;
    font-weight: 700;
    font-size: 1.25rem;
    color: var(--primary);
}

.logo-icon {
    font-size: 1.5rem;
}

.nav-menu {
    display: flex;
    list-style: none;
    gap: 0.25rem;
}

.nav-link {
    padding: 0.5rem 0.875rem;
    border-radius: var(--radius-sm);
    font-size: 0.875rem;
    font-weight: 500;
    color: var(--text-secondary);
    transition: var(--transition);
}

.nav-link:hover {
    background: var(--primary-bg);
    color: var(--primary);
}

.nav-toggle {
    display: none;
    flex-direction: column;
    gap: 5px;
    background: none;
    border: none;
    cursor: pointer;
    padding: 4px;
}

.nav-toggle span {
    width: 24px;
    height: 2px;
    background: var(--text);
    border-radius: 2px;
    transition: var(--transition);
}

.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(5px, -5px); }

/* ===== Hero ===== */
.hero {
    position: relative;
    min-height: 85vh;
    display: flex;
    align-items: center;
    justify-content: center;
    text-align: center;
    padding: 6rem 1.5rem 4rem;
    overflow: hidden;
}

.hero-bg {
    position: absolute;
    inset: 0;
    background: linear-gradient(135deg, #E3F2FD 0%, #BBDEFB 30%, #E8F5E9 60%, #FFF3E0 100%);
    z-index: 0;
}

.hero-bg::after {
    content: '';
    position: absolute;
    inset: 0;
    background: radial-gradient(ellipse at 30% 20%, rgba(21, 101, 192, 0.08) 0%, transparent 60%),
                radial-gradient(ellipse at 70% 80%, rgba(0, 200, 83, 0.06) 0%, transparent 60%);
}

.hero-content {
    position: relative;
    z-index: 1;
    max-width: 700px;
}

.hero-badge {
    display: inline-block;
    padding: 0.375rem 1rem;
    border-radius: 50px;
    background: rgba(21, 101, 192, 0.1);
    color: var(--primary);
    font-size: 0.8125rem;
    font-weight: 600;
    margin-bottom: 1.5rem;
    letter-spacing: 0.02em;
}

.hero h1 {
    font-size: clamp(2.5rem, 6vw, 4rem);
    font-weight: 800;
    line-height: 1.1;
    margin-bottom: 1.25rem;
    color: var(--bg-dark);
}

.gradient-text {
    background: linear-gradient(135deg, var(--primary) 0%, var(--primary-light) 50%, var(--accent) 100%);
    -webkit-background-clip: text;
    -webkit-text-fill-color: transparent;
    background-clip: text;
}

.hero-subtitle {
    font-size: 1.125rem;
    color: var(--text-secondary);
    margin-bottom: 2.5rem;
    line-height: 1.8;
}

.hero-actions {
    display: flex;
    gap: 1rem;
    justify-content: center;
    flex-wrap: wrap;
}

/* ===== Buttons ===== */
.btn {
    display: inline-flex;
    align-items: center;
    gap: 0.5rem;
    padding: 0.875rem 2rem;
    border-radius: 50px;
    font-size: 0.9375rem;
    font-weight: 600;
    cursor: pointer;
    transition: var(--transition);
    border: none;
}

.btn-primary {
    background: var(--primary);
    color: var(--text-on-primary);
    box-shadow: 0 4px 14px rgba(21, 101, 192, 0.3);
}

.btn-primary:hover {
    background: var(--primary-dark);
    box-shadow: 0 6px 20px rgba(21, 101, 192, 0.4);
    transform: translateY(-2px);
}

.btn-outline {
    background: transparent;
    color: var(--primary);
    border: 2px solid var(--primary);
}

.btn-outline:hover {
    background: var(--primary);
    color: var(--text-on-primary);
    transform: translateY(-2px);
}

.btn-icon {
    font-size: 0.75rem;
}

/* ===== Download Section ===== */
.section-download {
    background: linear-gradient(135deg, #E8F5E9 0%, #C8E6C9 50%, #E3F2FD 100%);
}

.download-card {
    display: flex;
    align-items: center;
    gap: 1.5rem;
    background: var(--surface);
    border-radius: var(--radius-lg);
    padding: 2rem 2.5rem;
    box-shadow: var(--shadow-lg);
    border: 2px solid rgba(0, 200, 83, 0.2);
    max-width: 700px;
    margin: 0 auto;
}

.download-icon {
    font-size: 3rem;
    flex-shrink: 0;
}

.download-info {
    flex: 1;
}

.download-info h3 {
    font-size: 1.25rem;
    font-weight: 700;
    margin-bottom: 0.25rem;
}

.download-info p {
    font-size: 0.875rem;
    color: var(--text-muted);
}

.btn-download {
    background: linear-gradient(135deg, var(--accent), var(--accent-dark));
    color: white;
    padding: 1rem 2rem;
    font-size: 1rem;
    font-weight: 700;
    box-shadow: 0 4px 14px rgba(0, 200, 83, 0.35);
    flex-shrink: 0;
}

.btn-download:hover {
    transform: translateY(-3px);
    box-shadow: 0 6px 20px rgba(0, 200, 83, 0.45);
}

/* ===== Sections ===== */
.section {
    padding: 5rem 0;
}

.section-alt {
    background: var(--bg-alt);
}

.section-header {
    text-align: center;
    margin-bottom: 3.5rem;
}

.section-badge {
    display: inline-block;
    padding: 0.375rem 1rem;
    border-radius: 50px;
    background: var(--primary-bg);
    color: var(--primary);
    font-size: 0.8125rem;
    font-weight: 600;
    margin-bottom: 1rem;
}

.section-header h2 {
    font-size: 2rem;
    font-weight: 800;
    margin-bottom: 0.75rem;
    color: var(--bg-dark);
}

.section-header p {
    font-size: 1.0625rem;
    color: var(--text-muted);
    max-width: 550px;
    margin: 0 auto;
}

/* ===== Video Wrapper ===== */
.video-wrapper {
    max-width: 800px;
    margin: 0 auto;
    border-radius: var(--radius-lg);
    overflow: hidden;
    box-shadow: var(--shadow-xl);
    aspect-ratio: 16 / 9;
    background: #0B1120;
}

.video-wrapper iframe {
    width: 100%;
    height: 100%;
}

.video-placeholder {
    width: 100%;
    height: 100%;
    display: flex;
    flex-direction: column;
    align-items: center;
    justify-content: center;
    background: linear-gradient(135deg, #1a1a2e, #16213e);
    gap: 0.75rem;
}

.video-placeholder-icon {
    font-size: 3rem;
    opacity: 0.6;
}

.video-placeholder p {
    font-size: 1.125rem;
    font-weight: 500;
    color: rgba(255, 255, 255, 0.5);
    letter-spacing: 0.05em;
}

/* ===== Tutorials Grid ===== */
.tutorials-grid {
    display: grid;
    grid-template-columns: repeat(3, 1fr);
    gap: 2rem;
    align-items: start;
}

.tutorial-card {
    background: var(--surface);
    border-radius: var(--radius-lg);
    padding: 1.75rem 1.5rem 1.5rem;
    box-shadow: var(--shadow-lg);
    border: 1px solid var(--border);
    transition: var(--transition);
    position: relative;
    display: flex;
    flex-direction: column;
    gap: 0.75rem;
}

.tutorial-card:hover {
    transform: translateY(-5px);
    box-shadow: var(--shadow-xl);
    border-color: var(--primary-light);
}

.tutorial-badge {
    width: 42px;
    height: 42px;
    border-radius: 50%;
    background: linear-gradient(135deg, var(--primary), var(--primary-light));
    color: white;
    font-size: 1.125rem;
    font-weight: 800;
    display: flex;
    align-items: center;
    justify-content: center;
    flex-shrink: 0;
    box-shadow: 0 3px 10px rgba(21, 101, 192, 0.35);
}

.tutorial-card h3 {
    font-size: 1.0625rem;
    font-weight: 700;
    color: var(--bg-dark);
    line-height: 1.3;
}

.tutorial-card > p {
    font-size: 0.875rem;
    color: var(--text-muted);
    margin-bottom: 0.25rem;
}

/* YouTube Shorts: portrait aspect ratio 9/16 */
.tutorial-video-wrapper {
    width: 100%;
    aspect-ratio: 9 / 16;
    border-radius: var(--radius);
    overflow: hidden;
    background: #0B1120;
    box-shadow: 0 4px 18px rgba(0,0,0,0.15);
}

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

/* ===== Steps Grid ===== */
.steps-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(220px, 1fr));
    gap: 1.5rem;
    margin-bottom: 2rem;
}

.step-card {
    background: var(--surface);
    border-radius: var(--radius);
    padding: 2rem 1.5rem;
    text-align: center;
    box-shadow: var(--shadow);
    transition: var(--transition);
    border: 1px solid var(--border);
}

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

.step-number {
    width: 48px;
    height: 48px;
    border-radius: 50%;
    background: linear-gradient(135deg, var(--primary), var(--primary-light));
    color: white;
    font-size: 1.25rem;
    font-weight: 700;
    display: flex;
    align-items: center;
    justify-content: center;
    margin: 0 auto 1rem;
}

.step-card h3 {
    font-size: 1.0625rem;
    font-weight: 700;
    margin-bottom: 0.5rem;
}

.step-card p {
    font-size: 0.9375rem;
    color: var(--text-secondary);
}

/* ===== Alert ===== */
.alert {
    display: flex;
    align-items: flex-start;
    gap: 0.75rem;
    padding: 1rem 1.25rem;
    border-radius: var(--radius-sm);
    margin: 1.5rem 0;
}

.alert-warning {
    background: #FFF8E1;
    border-left: 4px solid var(--warning);
}

.alert-icon {
    font-size: 1.25rem;
    flex-shrink: 0;
}

.alert p {
    font-size: 0.9375rem;
    color: var(--text);
}

/* ===== Subsections ===== */
.subsection {
    margin-top: 3rem;
    padding: 2rem;
    background: var(--surface);
    border-radius: var(--radius);
    border: 1px solid var(--border);
}

.subsection h3 {
    font-size: 1.125rem;
    font-weight: 700;
    margin-bottom: 1rem;
}

/* ===== Instruction List ===== */
.instruction-list {
    padding-left: 1.5rem;
}

.instruction-list li {
    margin-bottom: 0.5rem;
    font-size: 0.9375rem;
    color: var(--text-secondary);
}

.instruction-list li strong {
    color: var(--text);
}

/* ===== Check List ===== */
.check-list {
    list-style: none;
    padding: 0;
}

.check-list li {
    padding: 0.375rem 0;
    padding-left: 1.75rem;
    position: relative;
    font-size: 0.9375rem;
    color: var(--text-secondary);
}

.check-list li::before {
    content: '✓';
    position: absolute;
    left: 0;
    color: var(--accent);
    font-weight: 700;
}

/* ===== Feature Cards ===== */
.feature-cards {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(280px, 1fr));
    gap: 1.5rem;
}

.feature-card {
    background: var(--surface);
    border-radius: var(--radius);
    padding: 2rem;
    box-shadow: var(--shadow);
    border: 1px solid var(--border);
    transition: var(--transition);
}

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

.feature-icon {
    font-size: 2rem;
    margin-bottom: 1rem;
}

.feature-card h3 {
    font-size: 1.125rem;
    font-weight: 700;
    margin-bottom: 1rem;
}

.feature-detail {
    margin-top: 1rem;
    font-size: 0.875rem;
    color: var(--text-muted);
    border-top: 1px solid var(--border);
    padding-top: 1rem;
}

/* ===== Sync Flow ===== */
.sync-flow {
    display: flex;
    align-items: center;
    justify-content: center;
    gap: 1rem;
    margin-bottom: 3rem;
    flex-wrap: wrap;
}

.sync-step {
    flex: 1;
    min-width: 200px;
    max-width: 280px;
    background: var(--surface);
    border-radius: var(--radius);
    padding: 2rem 1.5rem;
    text-align: center;
    box-shadow: var(--shadow);
    border: 1px solid var(--border);
    transition: var(--transition);
}

.sync-step:hover {
    transform: translateY(-4px);
    box-shadow: var(--shadow-lg);
}

.sync-icon {
    font-size: 2rem;
    margin-bottom: 0.75rem;
}

.sync-step h4 {
    font-size: 1rem;
    font-weight: 700;
    margin-bottom: 0.5rem;
}

.sync-step p {
    font-size: 0.875rem;
    color: var(--text-secondary);
}

.sync-arrow {
    font-size: 1.5rem;
    color: var(--primary);
    font-weight: 700;
}

/* ===== Info Box ===== */
.info-box {
    background: var(--primary-bg);
    border-radius: var(--radius);
    padding: 2rem;
    border: 1px solid rgba(21, 101, 192, 0.15);
}

.info-box h3 {
    font-size: 1.125rem;
    font-weight: 700;
    margin-bottom: 0.75rem;
    color: var(--primary-dark);
}

.info-box p {
    font-size: 0.9375rem;
    color: var(--text-secondary);
    margin-bottom: 1rem;
}

.info-box code {
    background: rgba(21, 101, 192, 0.1);
    padding: 0.2em 0.5em;
    border-radius: 4px;
    font-size: 0.875rem;
    color: var(--primary-dark);
    font-weight: 600;
}

/* ===== Two Columns ===== */
.two-col {
    display: grid;
    grid-template-columns: 1fr 1fr;
    gap: 1.5rem;
}

.col-card {
    background: var(--surface);
    border-radius: var(--radius);
    padding: 2rem;
    box-shadow: var(--shadow);
    border: 1px solid var(--border);
    transition: var(--transition);
}

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

.col-card h3 {
    font-size: 1.125rem;
    font-weight: 700;
    margin-bottom: 0.75rem;
}

.col-card p {
    font-size: 0.9375rem;
    color: var(--text-secondary);
}

/* ===== Error Cards ===== */
.error-cards {
    display: flex;
    flex-direction: column;
    gap: 1.5rem;
}

.error-card {
    background: var(--surface);
    border-radius: var(--radius);
    overflow: hidden;
    box-shadow: var(--shadow);
    transition: var(--transition);
}

.error-card:hover {
    box-shadow: var(--shadow-lg);
}

.error-header {
    padding: 1.25rem 1.5rem;
    display: flex;
    align-items: center;
    gap: 1rem;
    flex-wrap: wrap;
}

.error-critical .error-header {
    background: linear-gradient(135deg, #FFEBEE, #FCE4EC);
    border-bottom: 2px solid var(--error);
}

.error-warning .error-header {
    background: linear-gradient(135deg, #FFF8E1, #FFF3E0);
    border-bottom: 2px solid var(--warning);
}

.error-info .error-header {
    background: linear-gradient(135deg, #E1F5FE, #E3F2FD);
    border-bottom: 2px solid var(--info);
}

.error-badge {
    display: inline-block;
    padding: 0.25rem 0.75rem;
    border-radius: 50px;
    font-size: 0.75rem;
    font-weight: 700;
    background: var(--error);
    color: white;
    flex-shrink: 0;
}

.error-badge.warning {
    background: var(--warning);
    color: #3E2723;
}

.error-badge.info {
    background: var(--info);
    color: white;
}

.error-header h3 {
    font-size: 0.9375rem;
    font-weight: 600;
    color: var(--text);
}

.error-body {
    padding: 1.5rem;
}

.error-body p {
    font-size: 0.9375rem;
    color: var(--text-secondary);
    margin-bottom: 1rem;
}

.error-body h4 {
    font-size: 0.875rem;
    font-weight: 700;
    margin-bottom: 0.5rem;
    color: var(--text);
}

.error-body ol {
    padding-left: 1.5rem;
    margin-bottom: 1rem;
}

.error-body ol li {
    font-size: 0.9375rem;
    color: var(--text-secondary);
    margin-bottom: 0.375rem;
}

.error-note {
    padding: 0.75rem 1rem;
    border-radius: var(--radius-sm);
    font-size: 0.875rem;
    background: #FFF3E0;
    border-left: 3px solid var(--warning);
    color: var(--text);
}

.error-note.success {
    background: #E8F5E9;
    border-left-color: var(--accent);
}

/* ===== Tips Grid ===== */
.tips-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(200px, 1fr));
    gap: 1.5rem;
    margin-bottom: 3rem;
}

.tip-card {
    background: var(--surface);
    border-radius: var(--radius);
    padding: 1.75rem 1.5rem;
    text-align: center;
    box-shadow: var(--shadow);
    border: 1px solid var(--border);
    transition: var(--transition);
}

.tip-card:hover {
    transform: translateY(-4px);
    box-shadow: var(--shadow-lg);
    border-color: var(--primary-light);
}

.tip-icon {
    font-size: 2rem;
    margin-bottom: 0.75rem;
}

.tip-card h3 {
    font-size: 1rem;
    font-weight: 700;
    margin-bottom: 0.5rem;
}

.tip-card p {
    font-size: 0.875rem;
    color: var(--text-secondary);
}

/* ===== Permissions Table ===== */
.permissions-table {
    background: var(--surface);
    border-radius: var(--radius);
    padding: 2rem;
    box-shadow: var(--shadow);
    border: 1px solid var(--border);
}

.permissions-table h3 {
    font-size: 1.125rem;
    font-weight: 700;
    margin-bottom: 1.25rem;
}

table {
    width: 100%;
    border-collapse: collapse;
}

th, td {
    padding: 0.875rem 1rem;
    text-align: left;
    font-size: 0.9375rem;
}

thead th {
    background: var(--bg-alt);
    font-weight: 600;
    color: var(--text);
    border-bottom: 2px solid var(--border);
}

tbody td {
    border-bottom: 1px solid var(--border);
    color: var(--text-secondary);
}

tbody tr:last-child td {
    border-bottom: none;
}

tbody tr:hover {
    background: var(--surface-hover);
}

/* ===== Privacy ===== */
.privacy-content {
    max-width: 800px;
    margin: 0 auto;
}

.privacy-block {
    margin-bottom: 2.5rem;
}

.privacy-block h3 {
    font-size: 1.125rem;
    font-weight: 700;
    margin-bottom: 0.75rem;
    color: var(--primary-dark);
}

.privacy-block p {
    font-size: 0.9375rem;
    color: var(--text-secondary);
    margin-bottom: 0.75rem;
}

.privacy-block ul {
    padding-left: 1.5rem;
}

.privacy-block ul li {
    font-size: 0.9375rem;
    color: var(--text-secondary);
    margin-bottom: 0.5rem;
}

/* ===== Footer ===== */
.footer {
    background: var(--bg-dark);
    padding: 3rem 0;
    text-align: center;
}

.footer-content {
    display: flex;
    flex-direction: column;
    align-items: center;
    gap: 0.75rem;
}

.footer-brand {
    display: flex;
    align-items: center;
    gap: 0.5rem;
}

.footer-name {
    font-size: 1.125rem;
    font-weight: 700;
    color: white;
}

.footer-version {
    font-size: 0.75rem;
    padding: 0.2rem 0.5rem;
    border-radius: 50px;
    background: rgba(255,255,255,0.1);
    color: rgba(255,255,255,0.7);
}

.footer-text {
    font-size: 0.875rem;
    color: rgba(255,255,255,0.5);
}

.footer-links a {
    font-size: 0.875rem;
    color: rgba(255,255,255,0.5);
    transition: var(--transition);
}

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

/* ===== Back to Top ===== */
.back-to-top {
    position: fixed;
    bottom: 2rem;
    right: 2rem;
    width: 48px;
    height: 48px;
    border-radius: 50%;
    background: var(--primary);
    color: white;
    border: none;
    font-size: 1.25rem;
    cursor: pointer;
    box-shadow: 0 4px 14px rgba(21, 101, 192, 0.3);
    opacity: 0;
    visibility: hidden;
    transform: translateY(10px);
    transition: var(--transition);
    z-index: 999;
}

.back-to-top.visible {
    opacity: 1;
    visibility: visible;
    transform: translateY(0);
}

.back-to-top:hover {
    background: var(--primary-dark);
    transform: translateY(-3px);
}

/* ===== Animations ===== */
.fade-in {
    opacity: 0;
    transform: translateY(24px);
    transition: opacity 0.6s ease, transform 0.6s ease;
}

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

/* Stagger animations */
.step-card:nth-child(2) { transition-delay: 0.1s; }
.step-card:nth-child(3) { transition-delay: 0.2s; }
.step-card:nth-child(4) { transition-delay: 0.3s; }

.feature-card:nth-child(2) { transition-delay: 0.1s; }
.feature-card:nth-child(3) { transition-delay: 0.2s; }

.tip-card:nth-child(2) { transition-delay: 0.05s; }
.tip-card:nth-child(3) { transition-delay: 0.10s; }
.tip-card:nth-child(4) { transition-delay: 0.15s; }
.tip-card:nth-child(5) { transition-delay: 0.20s; }
.tip-card:nth-child(6) { transition-delay: 0.25s; }

.error-card:nth-child(2) { transition-delay: 0.1s; }
.error-card:nth-child(3) { transition-delay: 0.2s; }
.error-card:nth-child(4) { transition-delay: 0.3s; }

/* ===== Responsive ===== */
@media (max-width: 768px) {
    .nav-toggle { display: flex; }

    .nav-menu {
        position: fixed;
        top: 64px;
        left: 0;
        right: 0;
        background: rgba(255,255,255,0.98);
        backdrop-filter: blur(16px);
        flex-direction: column;
        padding: 1rem;
        gap: 0.25rem;
        border-bottom: 1px solid var(--border);
        box-shadow: var(--shadow-lg);
        transform: translateY(-100%);
        opacity: 0;
        visibility: hidden;
        transition: var(--transition);
    }

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

    .nav-link {
        padding: 0.75rem 1rem;
        font-size: 1rem;
    }

    .hero {
        min-height: 75vh;
        padding: 5rem 1.5rem 3rem;
    }

    .hero h1 {
        font-size: 2.25rem;
    }

    .section {
        padding: 3.5rem 0;
    }

    .two-col {
        grid-template-columns: 1fr;
    }

    .sync-flow {
        flex-direction: column;
    }

    .sync-arrow {
        transform: rotate(90deg);
    }

    .sync-step {
        max-width: 100%;
    }

    .download-card {
        flex-direction: column;
        text-align: center;
        padding: 1.5rem;
    }

    .error-header {
        flex-direction: column;
        gap: 0.5rem;
        align-items: flex-start;
    }

    .tutorials-grid {
        grid-template-columns: 1fr;
        max-width: 400px;
        margin-left: auto;
        margin-right: auto;
    }

    .back-to-top {
        bottom: 1rem;
        right: 1rem;
    }
}

@media (max-width: 480px) {
    .hero-actions {
        flex-direction: column;
        align-items: center;
    }

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

    .tips-grid {
        grid-template-columns: 1fr 1fr;
    }

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

    .tutorial-card {
        max-width: 100%;
    }
}