:root {
    --primary: #4f46e5;
    --primary-hover: #4338ca;
    --primary-light: #eeebff;
    --success: #10b981;
    --success-light: #ecfdf5;
    --bg: #f8fafc;
    --surface: #ffffff;
    --text: #0f172a;
    --text-muted: #64748b;
    --border: #e2e8f0;
    --border-hover: #cbd5e1;
    --radius: 16px;
    --radius-sm: 8px;
    --shadow-sm: 0 1px 2px 0 rgba(0, 0, 0, 0.05);
    --shadow: 0 4px 6px -1px rgba(0, 0, 0, 0.1), 0 2px 4px -2px rgba(0, 0, 0, 0.1);
    --shadow-lg: 0 10px 15px -3px rgba(0, 0, 0, 0.1), 0 4px 6px -4px rgba(0, 0, 0, 0.1);
    --font: system-ui, -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, "Helvetica Neue", Arial, sans-serif;
}

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

body {
    font-family: var(--font);
    background-color: var(--bg);
    color: var(--text);
    line-height: 1.6;
    -webkit-font-smoothing: antialiased;
}

.container {
    width: 100%;
    max-width: 1200px;
    margin: 0 auto;
    padding: 0 24px;
}

/* Header */
.site-header {
    position: sticky;
    top: 0;
    z-index: 100;
    background-color: rgba(255, 255, 255, 0.8);
    backdrop-filter: blur(12px);
    -webkit-backdrop-filter: blur(12px);
    border-bottom: 1px solid var(--border);
}

.header-inner {
    display: flex;
    justify-content: space-between;
    align-items: center;
    height: 72px;
}

.logo {
    display: flex;
    align-items: center;
    gap: 8px;
    font-size: 22px;
    font-weight: 800;
    color: var(--text);
    text-decoration: none;
    letter-spacing: -0.5px;
}

.logo-icon {
    display: flex;
    align-items: center;
    justify-content: center;
    width: 32px;
    height: 32px;
    background-color: var(--primary-light);
    border-radius: 8px;
    color: var(--primary);
}

.nav {
    display: flex;
    align-items: center;
    gap: 32px;
}

.nav a {
    font-size: 15px;
    font-weight: 500;
    color: var(--text-muted);
    text-decoration: none;
    transition: color 0.2s ease;
}

.nav a:hover, .nav a.active {
    color: var(--primary);
}

/* Burger Menu */
.burger-btn {
    display: none;
    background: none;
    border: none;
    cursor: pointer;
    padding: 4px;
}

.burger-btn span {
    display: block;
    width: 24px;
    height: 2px;
    background-color: var(--text);
    margin: 5px 0;
    transition: 0.3s;
}

/* Hero Section */
.hero {
    padding: 64px 0 80px;
    text-align: center;
}

.hero h1 {
    font-size: 48px;
    font-weight: 800;
    line-height: 1.2;
    margin-bottom: 16px;
    letter-spacing: -1px;
}

.hero p.lead {
    font-size: 18px;
    color: var(--text-muted);
    max-width: 600px;
    margin: 0 auto 40px;
}

/* Upload Widget */
.upload-wrapper {
    max-width: 580px;
    margin: 0 auto;
}

.upload-card {
    background-color: var(--surface);
    border-radius: var(--radius);
    box-shadow: var(--shadow-lg);
    border: 1px solid var(--border);
    padding: 32px;
    transition: transform 0.2s ease, box-shadow 0.2s ease;
}

.drop-zone {
    border: 2px dashed var(--border);
    border-radius: var(--radius);
    padding: 48px 24px;
    background-color: #fafbfc;
    cursor: pointer;
    transition: all 0.2s ease;
    display: flex;
    flex-direction: column;
    align-items: center;
    justify-content: center;
}

.drop-zone:hover, .drop-zone.dragover {
    border-color: var(--primary);
    background-color: #f5f3ff;
}

.drop-zone-icon {
    width: 64px;
    height: 64px;
    background-color: var(--primary-light);
    color: var(--primary);
    border-radius: 50%;
    display: flex;
    align-items: center;
    justify-content: center;
    margin-bottom: 16px;
}

.drop-zone-text h3 {
    font-size: 18px;
    font-weight: 600;
    margin-bottom: 6px;
}

.drop-zone-text p {
    font-size: 14px;
    color: var(--text-muted);
}

.file-input {
    display: none;
}

/* Upload States */
.upload-state {
    display: none;
}

.progress-container {
    text-align: left;
    margin: 24px 0;
}

.file-info-header {
    display: flex;
    justify-content: space-between;
    margin-bottom: 8px;
    font-size: 14px;
    font-weight: 500;
}

.progress-bar-bg {
    width: 100%;
    height: 8px;
    background-color: var(--border);
    border-radius: 4px;
    overflow: hidden;
}

.progress-bar-fill {
    width: 0%;
    height: 100%;
    background-color: var(--primary);
    transition: width 0.1s linear;
}

.upload-status-text {
    font-size: 13px;
    color: var(--text-muted);
    margin-top: 6px;
}

/* Success State */
.success-container {
    text-align: center;
}

.success-icon {
    width: 56px;
    height: 56px;
    background-color: var(--success-light);
    color: var(--success);
    border-radius: 50%;
    display: flex;
    align-items: center;
    justify-content: center;
    margin: 0 auto 16px;
}

.success-title {
    font-size: 20px;
    font-weight: 700;
    margin-bottom: 6px;
}

.success-desc {
    font-size: 14px;
    color: var(--text-muted);
    margin-bottom: 24px;
}

.link-input-group {
    display: flex;
    gap: 8px;
    margin-bottom: 24px;
}

.link-input {
    flex: 1;
    height: 48px;
    border: 1px solid var(--border);
    border-radius: var(--radius-sm);
    padding: 0 16px;
    font-size: 14px;
    background-color: var(--bg);
    color: var(--text);
    outline: none;
    font-family: monospace;
}

.btn {
    display: inline-flex;
    align-items: center;
    justify-content: center;
    gap: 8px;
    height: 48px;
    padding: 0 24px;
    font-size: 15px;
    font-weight: 600;
    border-radius: var(--radius-sm);
    border: none;
    cursor: pointer;
    transition: all 0.2s ease;
    text-decoration: none;
}

.btn-primary {
    background-color: var(--primary);
    color: white;
}

.btn-primary:hover {
    background-color: var(--primary-hover);
}

.btn-outline {
    background-color: transparent;
    border: 1px solid var(--border);
    color: var(--text);
}

.btn-outline:hover {
    border-color: var(--text-muted);
    background-color: var(--bg);
}

.upload-limits {
    display: flex;
    justify-content: center;
    gap: 24px;
    margin-top: 24px;
}

.limit-item {
    display: flex;
    align-items: center;
    gap: 6px;
    font-size: 13px;
    color: var(--text-muted);
}

/* Recent Uploads */
.recent-section {
    padding: 40px 0 60px;
    display: none;
}

.recent-title {
    font-size: 20px;
    font-weight: 700;
    margin-bottom: 16px;
    text-align: center;
}

.recent-list {
    max-width: 580px;
    margin: 0 auto;
    background: var(--surface);
    border: 1px solid var(--border);
    border-radius: var(--radius);
    padding: 16px;
    display: flex;
    flex-direction: column;
    gap: 12px;
}

.recent-item {
    display: flex;
    align-items: center;
    justify-content: space-between;
    padding: 10px 12px;
    background: var(--bg);
    border-radius: var(--radius-sm);
    font-size: 14px;
}

.recent-file-details {
    display: flex;
    flex-direction: column;
    overflow: hidden;
    padding-right: 8px;
}

.recent-file-name {
    font-weight: 600;
    white-space: nowrap;
    text-overflow: ellipsis;
    overflow: hidden;
}

.recent-file-size {
    font-size: 12px;
    color: var(--text-muted);
}

/* Sections */
.section {
    padding: 80px 0;
    border-top: 1px solid var(--border);
}

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

.section-header {
    text-align: center;
    max-width: 600px;
    margin: 0 auto 56px;
}

.section-header h2 {
    font-size: 32px;
    font-weight: 800;
    margin-bottom: 12px;
}

.section-header p {
    color: var(--text-muted);
    font-size: 16px;
}

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

.grid-4 {
    display: grid;
    grid-template-columns: repeat(4, 1fr);
    gap: 24px;
}

/* Cards */
.card {
    background-color: var(--surface);
    border: 1px solid var(--border);
    border-radius: var(--radius);
    padding: 32px;
    transition: transform 0.2s ease, box-shadow 0.2s ease;
}

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

.card-icon {
    width: 48px;
    height: 48px;
    background-color: var(--primary-light);
    color: var(--primary);
    border-radius: 12px;
    display: flex;
    align-items: center;
    justify-content: center;
    margin-bottom: 24px;
}

.card h3 {
    font-size: 18px;
    font-weight: 700;
    margin-bottom: 12px;
}

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

/* Stats */
.stats-grid {
    display: grid;
    grid-template-columns: repeat(4, 1fr);
    gap: 32px;
    text-align: center;
}

.stat-item strong {
    display: block;
    font-size: 40px;
    font-weight: 800;
    color: var(--primary);
    line-height: 1;
    margin-bottom: 8px;
}

.stat-item span {
    font-size: 14px;
    color: var(--text-muted);
    font-weight: 500;
}

/* FAQ Details */
.faq-list {
    max-width: 800px;
    margin: 0 auto;
    display: flex;
    flex-direction: column;
    gap: 16px;
}

details {
    background-color: var(--surface);
    border: 1px solid var(--border);
    border-radius: var(--radius-sm);
    padding: 16px 24px;
    cursor: pointer;
    transition: all 0.2s ease;
}

details[open] {
    border-color: var(--border-hover);
    box-shadow: var(--shadow-sm);
}

summary {
    font-weight: 600;
    font-size: 16px;
    list-style: none;
    display: flex;
    justify-content: space-between;
    align-items: center;
}

summary::-webkit-details-marker {
    display: none;
}

summary::after {
    content: "+";
    font-size: 20px;
    font-weight: 400;
    color: var(--text-muted);
    transition: transform 0.2s ease;
}

details[open] summary::after {
    transform: rotate(45deg);
}

.faq-content {
    margin-top: 12px;
    padding-top: 12px;
    border-top: 1px solid var(--border);
    color: var(--text-muted);
    font-size: 15px;
    cursor: default;
}

/* Content Pages */
.page-hero {
    padding: 80px 0 48px;
    text-align: center;
    border-bottom: 1px solid var(--border);
    background-color: var(--surface);
}

.page-hero h1 {
    font-size: 40px;
    font-weight: 800;
    letter-spacing: -1px;
    margin-bottom: 12px;
}

.page-hero p {
    font-size: 18px;
    color: var(--text-muted);
}

.content-section {
    padding: 64px 0 96px;
}

.content-grid {
    display: grid;
    grid-template-columns: 280px 1fr;
    gap: 64px;
}

.sidebar-nav {
    position: sticky;
    top: 104px;
    align-self: start;
    display: flex;
    flex-direction: column;
    gap: 8px;
}

.sidebar-link {
    font-size: 14px;
    font-weight: 500;
    color: var(--text-muted);
    text-decoration: none;
    padding: 8px 12px;
    border-radius: 6px;
    transition: all 0.2s ease;
}

.sidebar-link:hover, .sidebar-link.active {
    color: var(--primary);
    background-color: var(--primary-light);
}

.rich-text {
    max-width: 720px;
}

.rich-text h2 {
    font-size: 24px;
    font-weight: 700;
    margin: 40px 0 16px;
}

.rich-text h2:first-child {
    margin-top: 0;
}

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

.rich-text ul {
    margin: 16px 0 24px 20px;
    color: var(--text-muted);
}

.rich-text li {
    margin-bottom: 8px;
}

/* Footer */
.site-footer {
    background-color: var(--surface);
    border-top: 1px solid var(--border);
    padding: 64px 0 32px;
}

.footer-top {
    display: flex;
    justify-content: space-between;
    margin-bottom: 48px;
}

.footer-info {
    max-width: 320px;
}

.footer-info p {
    color: var(--text-muted);
    font-size: 14px;
    margin-top: 12px;
}

.footer-links {
    display: flex;
    gap: 64px;
}

.footer-col h4 {
    font-size: 14px;
    font-weight: 700;
    text-transform: uppercase;
    letter-spacing: 0.5px;
    margin-bottom: 16px;
}

.footer-col ul {
    list-style: none;
    display: flex;
    flex-direction: column;
    gap: 12px;
}

.footer-col a {
    font-size: 14px;
    color: var(--text-muted);
    text-decoration: none;
    transition: color 0.2s ease;
}

.footer-col a:hover {
    color: var(--primary);
}

.footer-bottom {
    display: flex;
    justify-content: space-between;
    align-items: center;
    border-top: 1px solid var(--border);
    padding-top: 32px;
    font-size: 14px;
    color: var(--text-muted);
}

/* Toast */
.toast {
    position: fixed;
    bottom: 24px;
    left: 50%;
    transform: translateX(-50%) translateY(100px);
    background-color: var(--text);
    color: white;
    padding: 12px 24px;
    border-radius: var(--radius-sm);
    font-size: 14px;
    font-weight: 500;
    box-shadow: var(--shadow-lg);
    opacity: 0;
    transition: all 0.3s cubic-bezier(0.16, 1, 0.3, 1);
    z-index: 200;
}

.toast.show {
    transform: translateX(-50%) translateY(0);
    opacity: 1;
}

/* Responsive */
@media (max-width: 1024px) {
    .grid-4, .stats-grid {
        grid-template-columns: repeat(2, 1fr);
    }
}

@media (max-width: 768px) {
    .burger-btn {
        display: block;
    }
    
    .nav {
        display: none;
        position: absolute;
        top: 72px;
        left: 0;
        right: 0;
        background-color: var(--surface);
        flex-direction: column;
        padding: 24px;
        gap: 16px;
        border-bottom: 1px solid var(--border);
        box-shadow: var(--shadow);
    }
    
    .nav.active {
        display: flex;
    }
    
    .grid-3 {
        grid-template-columns: 1fr;
    }
    
    .content-grid {
        grid-template-columns: 1fr;
        gap: 32px;
    }
    
    .sidebar-nav {
        display: none;
    }
    
    .footer-top {
        flex-direction: column;
        gap: 40px;
    }
}

@media (max-width: 480px) {
    .hero h1 {
        font-size: 32px;
    }
    .grid-4, .stats-grid {
        grid-template-columns: 1fr;
    }
    .footer-links {
        flex-direction: column;
        gap: 32px;
    }
}