/* ===== AI Daily v2 - Timeline Design ===== */
:root {
    --bg-primary: #fafafa;
    --bg-secondary: #ffffff;
    --bg-tertiary: #f5f5f7;
    --text-primary: #1a1a2e;
    --text-secondary: #4a5568;
    --text-tertiary: #718096;
    --accent-primary: #6366f1;
    --accent-secondary: #8b5cf6;
    --accent-gradient: linear-gradient(135deg, #6366f1 0%, #8b5cf6 100%);
    --card-bg: #ffffff;
    --card-border: rgba(0, 0, 0, 0.06);
    --card-shadow: 0 1px 3px rgba(0, 0, 0, 0.04), 0 6px 16px rgba(0, 0, 0, 0.04);
    --card-shadow-hover: 0 4px 12px rgba(0, 0, 0, 0.08), 0 16px 32px rgba(0, 0, 0, 0.08);
    --border-color: rgba(0, 0, 0, 0.08);
    --nav-bg: rgba(255, 255, 255, 0.85);
    --radius-sm: 8px;
    --radius-md: 12px;
    --radius-lg: 16px;
    --radius-xl: 24px;
    --transition-fast: 0.15s ease;
    --transition-normal: 0.25s ease;
}

[data-theme="dark"] {
    --bg-primary: #0a0a0f;
    --bg-secondary: #12121a;
    --bg-tertiary: #1a1a2e;
    --text-primary: #f7fafc;
    --text-secondary: #cbd5e0;
    --text-tertiary: #a0aec0;
    --card-bg: #16162a;
    --card-border: rgba(255, 255, 255, 0.06);
    --card-shadow: 0 1px 3px rgba(0, 0, 0, 0.2), 0 6px 16px rgba(0, 0, 0, 0.2);
    --border-color: rgba(255, 255, 255, 0.08);
    --nav-bg: rgba(10, 10, 15, 0.9);
}

*, *::before, *::after { margin: 0; padding: 0; box-sizing: border-box; }
html { scroll-behavior: smooth; }

body {
    font-family: 'Inter', -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, sans-serif;
    background: var(--bg-primary);
    color: var(--text-primary);
    line-height: 1.6;
    min-height: 100vh;
    -webkit-font-smoothing: antialiased;
}

/* Navigation */
.nav {
    position: fixed;
    top: 0;
    left: 0;
    right: 0;
    z-index: 1000;
    background: var(--nav-bg);
    backdrop-filter: blur(20px);
    border-bottom: 1px solid var(--border-color);
}

.nav-content {
    max-width: 1200px;
    margin: 0 auto;
    padding: 0 24px;
    height: 56px;
    display: flex;
    align-items: center;
    justify-content: space-between;
}

.logo {
    display: flex;
    align-items: center;
    gap: 8px;
    font-weight: 700;
    font-size: 1.25rem;
    background: var(--accent-gradient);
    -webkit-background-clip: text;
    -webkit-text-fill-color: transparent;
}

.logo-icon { font-size: 1.4rem; }

.nav-info {
    display: flex;
    align-items: center;
    gap: 16px;
    font-size: 0.85rem;
    color: var(--text-tertiary);
}

.nav-date { font-weight: 500; color: var(--text-secondary); }
.nav-count { opacity: 0.8; }

.theme-toggle {
    width: 36px;
    height: 36px;
    border: 1px solid var(--border-color);
    background: var(--bg-secondary);
    border-radius: var(--radius-sm);
    cursor: pointer;
    display: flex;
    align-items: center;
    justify-content: center;
    font-size: 1.1rem;
    transition: all var(--transition-fast);
}

.theme-toggle:hover { transform: scale(1.05); border-color: var(--accent-primary); }
.icon-sun { display: inline; }
.icon-moon { display: none; }
[data-theme="dark"] .icon-sun { display: none; }
[data-theme="dark"] .icon-moon { display: inline; }

/* Hero */
.hero {
    position: relative;
    padding: 100px 24px 40px;
    text-align: center;
    overflow: hidden;
}

.hero::before {
    content: '';
    position: absolute;
    top: 0;
    left: 50%;
    transform: translateX(-50%);
    width: 100%;
    max-width: 800px;
    height: 100%;
    background: radial-gradient(ellipse at center, rgba(99, 102, 241, 0.1) 0%, transparent 70%);
    pointer-events: none;
}

[data-theme="dark"] .hero::before {
    background: radial-gradient(ellipse at center, rgba(139, 92, 246, 0.15) 0%, transparent 70%);
}

.hero-content { position: relative; z-index: 1; }

.hero-title {
    font-size: clamp(2rem, 6vw, 3.5rem);
    font-weight: 800;
    letter-spacing: -0.03em;
    margin-bottom: 12px;
    background: var(--accent-gradient);
    -webkit-background-clip: text;
    -webkit-text-fill-color: transparent;
}

.hero-subtitle {
    font-size: 1.1rem;
    color: var(--text-secondary);
    font-weight: 400;
    margin-bottom: 8px;
}

.hero-author {
    font-size: 0.9rem;
    color: var(--text-tertiary);
}

/* Filter Bar */
.filter-bar {
    position: sticky;
    top: 56px;
    z-index: 100;
    background: var(--nav-bg);
    backdrop-filter: blur(20px);
    border-bottom: 1px solid var(--border-color);
    padding: 12px 0;
}

.filter-content {
    max-width: 1200px;
    margin: 0 auto;
    padding: 0 16px;
}

.category-tabs {
    display: flex;
    gap: 8px;
    overflow-x: auto;
    padding-bottom: 4px;
    scrollbar-width: none;
    -ms-overflow-style: none;
}

.category-tabs::-webkit-scrollbar { display: none; }

.cat-tab {
    display: flex;
    align-items: center;
    gap: 6px;
    padding: 8px 14px;
    border: 1px solid var(--border-color);
    background: var(--bg-secondary);
    border-radius: 100px;
    font-size: 0.85rem;
    font-weight: 500;
    color: var(--text-secondary);
    cursor: pointer;
    transition: all var(--transition-fast);
    white-space: nowrap;
    flex-shrink: 0;
}

.cat-tab:hover {
    border-color: var(--accent-primary);
    color: var(--accent-primary);
}

.cat-tab.active {
    background: var(--accent-gradient);
    border-color: transparent;
    color: white;
}

.cat-icon { font-size: 1rem; }
.cat-count {
    font-size: 0.75rem;
    background: rgba(255, 255, 255, 0.2);
    padding: 2px 8px;
    border-radius: 100px;
    min-width: 24px;
    text-align: center;
}

.cat-tab:not(.active) .cat-count {
    background: var(--bg-tertiary);
}

/* Main */
.main {
    max-width: 1200px;
    margin: 0 auto;
    padding: 32px 16px 100px;
}

/* Timeline */
.timeline {
    display: flex;
    flex-direction: column;
    gap: 40px;
}

.timeline-group {
    animation: fadeInUp 0.4s ease forwards;
}

.timeline-header {
    display: flex;
    align-items: center;
    gap: 12px;
    margin-bottom: 20px;
    padding-bottom: 12px;
    border-bottom: 2px solid var(--border-color);
}

.timeline-date {
    font-size: 1.25rem;
    font-weight: 700;
    color: var(--text-primary);
}

.timeline-count {
    font-size: 0.85rem;
    color: var(--text-tertiary);
    background: var(--bg-tertiary);
    padding: 4px 12px;
    border-radius: 100px;
}

/* News Grid */
.news-grid {
    display: grid;
    grid-template-columns: repeat(auto-fill, minmax(320px, 1fr));
    gap: 16px;
}

/* News Card - Compact */
.news-card {
    background: var(--card-bg);
    border-radius: var(--radius-lg);
    border: 1px solid var(--card-border);
    transition: all var(--transition-normal);
    cursor: pointer;
    display: flex;
    flex-direction: column;
    overflow: hidden;
}

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

.news-card-icon {
    width: 100%;
    height: 60px;
    display: flex;
    align-items: center;
    justify-content: center;
    font-size: 1.8rem;
    background: var(--accent-gradient);
    flex-shrink: 0;
}

.news-card-content {
    padding: 16px;
    flex: 1;
    display: flex;
    flex-direction: column;
}

.news-card-category {
    display: inline-flex;
    font-size: 0.7rem;
    font-weight: 600;
    padding: 3px 10px;
    border-radius: 100px;
    margin-bottom: 10px;
    width: fit-content;
    background: currentColor;
    background-clip: padding-box;
    position: relative;
}

.news-card-category::before {
    content: '';
    position: absolute;
    inset: 0;
    background: currentColor;
    opacity: 0.12;
    border-radius: inherit;
}

.news-card-title {
    font-size: 0.95rem;
    font-weight: 600;
    line-height: 1.45;
    margin-bottom: 8px;
    display: -webkit-box;
    -webkit-line-clamp: 2;
    -webkit-box-orient: vertical;
    overflow: hidden;
}

.news-card-summary {
    font-size: 0.8rem;
    color: var(--text-secondary);
    line-height: 1.55;
    display: -webkit-box;
    -webkit-line-clamp: 2;
    -webkit-box-orient: vertical;
    overflow: hidden;
    margin-bottom: 12px;
    flex: 1;
}

.news-card-meta {
    display: flex;
    justify-content: space-between;
    align-items: center;
    font-size: 0.7rem;
    color: var(--text-tertiary);
}

.news-source { font-weight: 500; }
.news-time { opacity: 0.7; }

/* Loading */
.loading { text-align: center; padding: 60px 20px; color: var(--text-secondary); }
.loading-spinner {
    width: 40px; height: 40px;
    border: 3px solid var(--border-color);
    border-top-color: var(--accent-primary);
    border-radius: 50%;
    margin: 0 auto 16px;
    animation: spin 0.8s linear infinite;
}
@keyframes spin { to { transform: rotate(360deg); } }

/* Load More */
.load-more { text-align: center; padding: 32px 20px; }
.load-more-btn {
    padding: 12px 32px;
    background: var(--bg-secondary);
    border: 1px solid var(--border-color);
    border-radius: 100px;
    font-size: 0.9rem;
    font-weight: 500;
    color: var(--text-secondary);
    cursor: pointer;
    transition: all var(--transition-fast);
}
.load-more-btn:hover {
    background: var(--accent-gradient);
    border-color: transparent;
    color: white;
    transform: translateY(-2px);
}

.empty-state { text-align: center; padding: 80px 20px; color: var(--text-secondary); }
.empty-icon { font-size: 4rem; margin-bottom: 16px; display: block; }
.empty-hint { font-size: 0.85rem; opacity: 0.7; margin-top: 8px; }

/* Footer */
.footer {
    background: var(--bg-secondary);
    padding: 40px 24px;
    text-align: center;
    border-top: 1px solid var(--border-color);
}
.footer-content p { color: var(--text-secondary); font-size: 0.85rem; }
.footer-links { margin-top: 8px; }
.footer-links a { color: var(--accent-primary); text-decoration: none; font-weight: 500; }
.footer-links a:hover { color: var(--accent-secondary); }

/* Responsive */
@media (max-width: 768px) {
    .hero { padding: 80px 16px 32px; }
    .hero-title { font-size: 1.8rem; }
    .hero-subtitle { font-size: 1rem; }
    .nav-info { display: none; }
    .main { padding: 24px 12px 80px; }
    .timeline { gap: 28px; }
    .news-grid { grid-template-columns: 1fr; gap: 12px; }
    .news-card-icon { height: 48px; font-size: 1.5rem; }
}

/* Animations */
@keyframes fadeInUp {
    from { opacity: 0; transform: translateY(16px); }
    to { opacity: 1; transform: translateY(0); }
}

.news-card { 
    animation: fadeInUp 0.3s ease forwards; 
    opacity: 0; 
}

/* Category-specific colors for icons */
.news-card[data-category="headline"] .news-card-icon { background: linear-gradient(135deg, #ef4444, #f97316); }
.news-card[data-category="llm"] .news-card-icon { background: linear-gradient(135deg, #8b5cf6, #a855f7); }
.news-card[data-category="product"] .news-card-icon { background: linear-gradient(135deg, #06b6d4, #0891b2); }
.news-card[data-category="industry"] .news-card-icon { background: linear-gradient(135deg, #10b981, #059669); }
.news-card[data-category="tech"] .news-card-icon { background: linear-gradient(135deg, #f59e0b, #d97706); }
.news-card[data-category="policy"] .news-card-icon { background: linear-gradient(135deg, #ec4899, #db2777); }
.news-card[data-category="funding"] .news-card-icon { background: linear-gradient(135deg, #14b8a6, #0d9488); }