/* ========================================
   AI Research Daily — Apple/ChatGPT Style
   ======================================== */

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

:root {
  /* Light Theme */
  --bg-primary: #ffffff;
  --bg-secondary: #f5f5f7;
  --bg-tertiary: #fbfbfd;
  --text-primary: #1d1d1f;
  --text-secondary: #6e6e73;
  --text-tertiary: #86868b;
  --accent: #0071e3;
  --accent-hover: #0077ed;
  --accent-soft: rgba(0, 113, 227, 0.08);
  --gradient-1: #667eea;
  --gradient-2: #764ba2;
  --gradient-3: #f093fb;
  --border: rgba(0, 0, 0, 0.08);
  --border-strong: #d2d2d7;
  --shadow-sm: 0 1px 2px rgba(0,0,0,0.04);
  --shadow-md: 0 4px 12px rgba(0,0,0,0.06);
  --shadow-lg: 0 12px 40px rgba(0,0,0,0.08);
  --shadow-xl: 0 24px 60px rgba(0,0,0,0.1);
  --card-bg: #ffffff;
  --card-hover: #fafafa;
  --nav-bg: rgba(255, 255, 255, 0.82);
  --tag-bg: #f0f0f2;
  --tag-text: #6e6e73;
  --code-bg: #f5f5f7;
  --divider: #e8e8ed;
  --hero-gradient: linear-gradient(135deg, #667eea 0%, #764ba2 50%, #f093fb 100%);
  --radius-sm: 8px;
  --radius-md: 16px;
  --radius-lg: 24px;
  --radius-xl: 32px;
  --transition: 0.3s cubic-bezier(0.25, 0.1, 0.25, 1);
  --font-sans: -apple-system, BlinkMacSystemFont, 'SF Pro Display', 'SF Pro Text', 'Helvetica Neue', 'Segoe UI', Roboto, sans-serif;
  --font-serif: 'New York', 'Noto Serif SC', Georgia, serif;
  --font-mono: 'SF Mono', 'Fira Code', 'JetBrains Mono', monospace;
  --container: 1200px;
  --container-narrow: 860px;
}

[data-theme="dark"] {
  --bg-primary: #000000;
  --bg-secondary: #1c1c1e;
  --bg-tertiary: #111111;
  --text-primary: #f5f5f7;
  --text-secondary: #a1a1a6;
  --text-tertiary: #6e6e73;
  --accent: #2997ff;
  --accent-hover: #40a9ff;
  --accent-soft: rgba(41, 151, 255, 0.1);
  --gradient-1: #667eea;
  --gradient-2: #a855f7;
  --gradient-3: #f0abfc;
  --border: rgba(255, 255, 255, 0.08);
  --border-strong: #424245;
  --shadow-sm: 0 1px 2px rgba(0,0,0,0.3);
  --shadow-md: 0 4px 12px rgba(0,0,0,0.4);
  --shadow-lg: 0 12px 40px rgba(0,0,0,0.5);
  --shadow-xl: 0 24px 60px rgba(0,0,0,0.6);
  --card-bg: #1c1c1e;
  --card-hover: #2c2c2e;
  --nav-bg: rgba(0, 0, 0, 0.82);
  --tag-bg: #2c2c2e;
  --tag-text: #a1a1a6;
  --code-bg: #1c1c1e;
  --divider: #38383a;
}

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

body {
  font-family: var(--font-sans);
  background: var(--bg-primary);
  color: var(--text-primary);
  line-height: 1.6;
  transition: background var(--transition), color var(--transition);
  overflow-x: hidden;
}

a {
  color: var(--accent);
  text-decoration: none;
  transition: color var(--transition);
}
a:hover { color: var(--accent-hover); }

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

::selection {
  background: var(--accent);
  color: #fff;
}

/* ===== Layout ===== */
.container {
  max-width: var(--container);
  margin: 0 auto;
  padding: 0 24px;
}

.container--narrow {
  max-width: var(--container-narrow);
}

/* ===== Navigation ===== */
.nav {
  position: fixed;
  top: 0;
  left: 0;
  right: 0;
  z-index: 1000;
  background: var(--nav-bg);
  backdrop-filter: saturate(180%) blur(20px);
  -webkit-backdrop-filter: saturate(180%) blur(20px);
  border-bottom: 0.5px solid var(--border);
  transition: background var(--transition);
}

.nav__inner {
  display: flex;
  align-items: center;
  justify-content: space-between;
  height: 52px;
  max-width: var(--container);
  margin: 0 auto;
  padding: 0 24px;
}

.nav__logo {
  display: flex;
  align-items: center;
  gap: 10px;
  font-size: 17px;
  font-weight: 600;
  color: var(--text-primary);
  letter-spacing: -0.02em;
}

.nav__logo-icon {
  width: 28px;
  height: 28px;
  border-radius: 8px;
  background: var(--hero-gradient);
  display: flex;
  align-items: center;
  justify-content: center;
  font-size: 14px;
  color: #fff;
}

.nav__actions {
  display: flex;
  align-items: center;
  gap: 12px;
}

.nav__link {
  font-size: 14px;
  color: var(--text-secondary);
  padding: 6px 12px;
  border-radius: 980px;
  transition: all var(--transition);
}
.nav__link:hover {
  color: var(--text-primary);
  background: var(--bg-secondary);
}
.nav__link.active {
  color: var(--accent);
  font-weight: 600;
}

.theme-toggle {
  width: 36px;
  height: 36px;
  border-radius: 50%;
  border: none;
  background: var(--tag-bg);
  color: var(--text-secondary);
  cursor: pointer;
  display: flex;
  align-items: center;
  justify-content: center;
  font-size: 16px;
  transition: all var(--transition);
}
.theme-toggle:hover {
  background: var(--bg-secondary);
  color: var(--text-primary);
  transform: rotate(15deg);
}

/* ===== Hero Section ===== */
.hero {
  padding: 140px 24px 80px;
  text-align: center;
  position: relative;
  overflow: hidden;
}

.hero::before {
  content: '';
  position: absolute;
  top: -50%;
  left: -50%;
  width: 200%;
  height: 200%;
  background: radial-gradient(ellipse at 30% 20%, rgba(102,126,234,0.12) 0%, transparent 50%),
              radial-gradient(ellipse at 70% 80%, rgba(118,75,162,0.08) 0%, transparent 50%);
  pointer-events: none;
}

[data-theme="dark"] .hero::before {
  background: radial-gradient(ellipse at 30% 20%, rgba(102,126,234,0.06) 0%, transparent 50%),
              radial-gradient(ellipse at 70% 80%, rgba(168,85,247,0.04) 0%, transparent 50%);
}

.hero__badge {
  display: inline-flex;
  align-items: center;
  gap: 6px;
  padding: 6px 16px;
  border-radius: 980px;
  background: var(--accent-soft);
  color: var(--accent);
  font-size: 13px;
  font-weight: 500;
  margin-bottom: 24px;
  letter-spacing: 0.02em;
}

.hero__badge-dot {
  width: 6px;
  height: 6px;
  border-radius: 50%;
  background: var(--accent);
  animation: pulse 2s infinite;
}

@keyframes pulse {
  0%, 100% { opacity: 1; transform: scale(1); }
  50% { opacity: 0.5; transform: scale(0.8); }
}

.hero__title {
  font-size: clamp(36px, 6vw, 64px);
  font-weight: 700;
  line-height: 1.08;
  letter-spacing: -0.035em;
  margin-bottom: 20px;
  position: relative;
}

.hero__title-gradient {
  background: var(--hero-gradient);
  -webkit-background-clip: text;
  -webkit-text-fill-color: transparent;
  background-clip: text;
}

.hero__subtitle {
  font-size: clamp(17px, 2.2vw, 21px);
  color: var(--text-secondary);
  max-width: 640px;
  margin: 0 auto 40px;
  line-height: 1.5;
  font-weight: 400;
}

.hero__stats {
  display: flex;
  justify-content: center;
  gap: 48px;
  flex-wrap: wrap;
}

.hero__stat {
  text-align: center;
}

.hero__stat-value {
  font-size: 28px;
  font-weight: 700;
  color: var(--text-primary);
  letter-spacing: -0.02em;
}

.hero__stat-label {
  font-size: 13px;
  color: var(--text-tertiary);
  margin-top: 2px;
  text-transform: uppercase;
  letter-spacing: 0.06em;
}

/* ===== Filter Tags ===== */
.filters {
  padding: 0 24px 48px;
  display: flex;
  justify-content: center;
  flex-wrap: wrap;
  gap: 8px;
}

.filter-tag {
  padding: 8px 18px;
  border-radius: 980px;
  border: 1px solid var(--border-strong);
  background: transparent;
  color: var(--text-secondary);
  font-size: 14px;
  font-weight: 500;
  cursor: pointer;
  transition: all var(--transition);
  font-family: var(--font-sans);
}

.filter-tag:hover {
  border-color: var(--accent);
  color: var(--accent);
  background: var(--accent-soft);
}

.filter-tag.active {
  background: var(--text-primary);
  color: var(--bg-primary);
  border-color: var(--text-primary);
}

/* Topic group filters — hierarchical filter bar */
.filters__scroll {
  overflow-x: auto;
  -webkit-overflow-scrolling: touch;
  scrollbar-width: none;
}
.filters__scroll::-webkit-scrollbar { display: none; }

.filters__inner {
  display: inline-flex;
  flex-direction: column;
  gap: 10px;
  min-width: max-content;
  padding: 0 0 4px;
}

.filter-group {
  display: flex;
  align-items: center;
  gap: 6px;
  flex-wrap: nowrap;
}

.filter-group__label {
  font-size: 11px;
  font-weight: 600;
  color: var(--text-tertiary);
  white-space: nowrap;
  min-width: fit-content;
  padding: 0 4px;
  letter-spacing: 0.02em;
}

.filter-group__tags {
  display: flex;
  gap: 6px;
  flex-wrap: nowrap;
}

/* ===== Report Grid ===== */
.reports {
  padding: 0 24px 120px;
}

.reports__grid {
  display: grid;
  grid-template-columns: repeat(auto-fill, minmax(360px, 1fr));
  gap: 24px;
  max-width: var(--container);
  margin: 0 auto;
}

.report-card {
  background: var(--card-bg);
  border-radius: var(--radius-lg);
  border: 1px solid var(--border);
  overflow: hidden;
  transition: all var(--transition);
  cursor: pointer;
  text-decoration: none;
  color: inherit;
  display: flex;
  flex-direction: column;
}

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

.report-card__header {
  position: relative;
  height: 200px;
  overflow: hidden;
}

.report-card__gradient {
  width: 100%;
  height: 100%;
  transition: transform 0.6s ease;
}

.report-card:hover .report-card__gradient {
  transform: scale(1.05);
}

.report-card__date-badge {
  position: absolute;
  top: 16px;
  right: 16px;
  background: rgba(0,0,0,0.3);
  backdrop-filter: blur(10px);
  color: #fff;
  padding: 4px 12px;
  border-radius: 980px;
  font-size: 12px;
  font-weight: 500;
  letter-spacing: 0.02em;
}

.report-card__category-icon {
  position: absolute;
  top: 16px;
  left: 16px;
  width: 40px;
  height: 40px;
  border-radius: 12px;
  background: rgba(255,255,255,0.2);
  backdrop-filter: blur(10px);
  display: flex;
  align-items: center;
  justify-content: center;
  font-size: 20px;
}

.report-card__body {
  padding: 24px;
  flex: 1;
  display: flex;
  flex-direction: column;
}

.report-card__tag {
  display: inline-block;
  padding: 4px 10px;
  border-radius: 980px;
  background: var(--accent-soft);
  color: var(--accent);
  font-size: 12px;
  font-weight: 500;
  margin-bottom: 12px;
  width: fit-content;
}

.report-card__title {
  font-size: 18px;
  font-weight: 600;
  line-height: 1.35;
  letter-spacing: -0.02em;
  margin-bottom: 8px;
  color: var(--text-primary);
  display: -webkit-box;
  -webkit-line-clamp: 2;
  -webkit-box-orient: vertical;
  overflow: hidden;
}

.report-card__en-title {
  font-size: 13px;
  color: var(--text-tertiary);
  margin-bottom: 12px;
  display: -webkit-box;
  -webkit-line-clamp: 1;
  -webkit-box-orient: vertical;
  overflow: hidden;
  font-style: italic;
}

.report-card__excerpt {
  font-size: 14px;
  color: var(--text-secondary);
  line-height: 1.6;
  flex: 1;
  display: -webkit-box;
  -webkit-line-clamp: 3;
  -webkit-box-orient: vertical;
  overflow: hidden;
  margin-bottom: 16px;
}

.report-card__footer {
  display: flex;
  align-items: center;
  justify-content: space-between;
  padding-top: 16px;
  border-top: 1px solid var(--border);
}

.report-card__authors {
  font-size: 12px;
  color: var(--text-tertiary);
  max-width: 70%;
  white-space: nowrap;
  overflow: hidden;
  text-overflow: ellipsis;
}

.report-card__reading-time {
  font-size: 12px;
  color: var(--text-tertiary);
  margin-right: auto;
}

.report-card__read-more {
  font-size: 13px;
  font-weight: 500;
  color: var(--accent);
  display: flex;
  align-items: center;
  gap: 4px;
  transition: gap var(--transition);
}

.report-card:hover .report-card__read-more {
  gap: 8px;
}

/* ===== Venue Badge ===== */
.report-card__venue {
  display: inline-flex;
  align-items: center;
  padding: 2px 8px;
  border-radius: 4px;
  font-size: 11px;
  font-weight: 500;
  margin-right: 8px;
  white-space: nowrap;
  letter-spacing: 0.02em;
}

.report-card__venue--top {
  background: linear-gradient(135deg, #667eea 0%, #764ba2 100%);
  color: white;
  box-shadow: 0 1px 3px rgba(102, 126, 234, 0.3);
}

.report-card__venue--normal {
  background: var(--tag-bg);
  color: var(--tag-text);
}

.report-card__venue--preprint {
  background: var(--tag-bg);
  color: var(--text-tertiary);
  font-style: italic;
}

/* ===== Empty State ===== */
.empty-state {
  text-align: center;
  padding: 80px 24px;
  color: var(--text-secondary);
}

.empty-state__icon {
  font-size: 64px;
  margin-bottom: 24px;
}

.empty-state__title {
  font-size: 24px;
  font-weight: 600;
  color: var(--text-primary);
  margin-bottom: 8px;
}

.empty-state__desc {
  font-size: 16px;
  max-width: 400px;
  margin: 0 auto;
}

/* ===== Report Page ===== */
.report {
  padding-top: 52px;
}

.report__hero {
  padding: 100px 24px 60px;
  text-align: center;
  position: relative;
}

.report__hero::before {
  content: '';
  position: absolute;
  inset: 0;
  background: var(--hero-gradient);
  opacity: 0.04;
}

[data-theme="dark"] .report__hero::before {
  opacity: 0.06;
}

.report__back {
  display: inline-flex;
  align-items: center;
  gap: 6px;
  font-size: 14px;
  color: var(--text-secondary);
  margin-bottom: 32px;
  padding: 8px 16px;
  border-radius: 980px;
  background: var(--tag-bg);
  transition: all var(--transition);
  position: relative;
}
.report__back:hover {
  color: var(--text-primary);
  background: var(--bg-secondary);
  transform: translateX(-2px);
}

.report__category {
  display: inline-flex;
  align-items: center;
  gap: 6px;
  padding: 6px 16px;
  border-radius: 980px;
  background: var(--accent-soft);
  color: var(--accent);
  font-size: 13px;
  font-weight: 500;
  margin-bottom: 24px;
}

.report__title {
  font-size: clamp(28px, 4.5vw, 48px);
  font-weight: 700;
  line-height: 1.12;
  letter-spacing: -0.03em;
  margin-bottom: 12px;
  max-width: 900px;
  margin-left: auto;
  margin-right: auto;
}

.report__en-title {
  font-size: clamp(16px, 2vw, 20px);
  color: var(--text-tertiary);
  font-style: italic;
  margin-bottom: 24px;
  font-weight: 400;
}

.report__meta {
  display: flex;
  align-items: center;
  justify-content: center;
  gap: 24px;
  flex-wrap: wrap;
  color: var(--text-secondary);
  font-size: 14px;
}

.report__meta-item {
  display: flex;
  align-items: center;
  gap: 6px;
}

.report__meta-divider {
  width: 4px;
  height: 4px;
  border-radius: 50%;
  background: var(--text-tertiary);
}

/* Venue in report meta */
.report__meta-item--venue {
  display: inline-flex;
  align-items: center;
  padding: 3px 12px;
  border-radius: 6px;
  font-weight: 500;
  font-size: 13px;
  letter-spacing: 0.02em;
}

.report__meta-item--venue.top {
  background: linear-gradient(135deg, #667eea 0%, #764ba2 100%);
  color: white;
  box-shadow: 0 2px 6px rgba(102, 126, 234, 0.3);
}

.report__meta-item--venue.normal {
  background: var(--tag-bg);
  color: var(--tag-text);
}

.report__meta-item--venue.preprint {
  background: var(--tag-bg);
  color: var(--text-tertiary);
  font-style: italic;
}

/* Report Content */
.report__content {
  max-width: var(--container-narrow);
  margin: 0 auto;
  padding: 40px 24px 120px;
}

.report__toc {
  background: var(--bg-secondary);
  border-radius: var(--radius-md);
  padding: 24px 32px;
  margin-bottom: 48px;
  border: 1px solid var(--border);
}

.report__toc-title {
  font-size: 14px;
  font-weight: 600;
  text-transform: uppercase;
  letter-spacing: 0.08em;
  color: var(--text-tertiary);
  margin-bottom: 12px;
}

.report__toc-list {
  list-style: none;
}

.report__toc-list li {
  margin-bottom: 6px;
}

.report__toc-list a {
  font-size: 15px;
  color: var(--text-secondary);
  transition: color var(--transition);
  display: flex;
  align-items: center;
  gap: 8px;
}

.report__toc-list a::before {
  content: '';
  width: 4px;
  height: 4px;
  border-radius: 50%;
  background: var(--accent);
  opacity: 0;
  transition: opacity var(--transition);
}

.report__toc-list a:hover {
  color: var(--accent);
}

.report__toc-list a:hover::before {
  opacity: 1;
}

/* Content Sections */
.report__section {
  margin-bottom: 48px;
}

.report__section-title {
  font-size: 28px;
  font-weight: 700;
  letter-spacing: -0.02em;
  margin-bottom: 20px;
  padding-bottom: 12px;
  border-bottom: 2px solid var(--border);
  display: flex;
  align-items: center;
  gap: 12px;
}

.report__section-icon {
  font-size: 24px;
}

.report__text {
  font-size: 17px;
  line-height: 1.8;
  color: var(--text-secondary);
  margin-bottom: 16px;
  font-family: var(--font-serif);
}

.report__text strong {
  color: var(--text-primary);
  font-weight: 600;
}

/* Key Points / Callouts */
.report__callout {
  background: var(--accent-soft);
  border-left: 3px solid var(--accent);
  border-radius: 0 var(--radius-sm) var(--radius-sm) 0;
  padding: 20px 24px;
  margin: 24px 0;
}

.report__callout-title {
  font-size: 14px;
  font-weight: 600;
  color: var(--accent);
  text-transform: uppercase;
  letter-spacing: 0.06em;
  margin-bottom: 8px;
}

.report__callout-text {
  font-size: 15px;
  line-height: 1.7;
  color: var(--text-secondary);
}

.report__callout-text strong {
  color: var(--text-primary);
}

/* Lists */
.report__list {
  margin: 16px 0;
  padding-left: 0;
  list-style: none;
}

.report__list li {
  font-size: 16px;
  line-height: 1.7;
  color: var(--text-secondary);
  padding: 6px 0 6px 24px;
  position: relative;
  font-family: var(--font-serif);
}

.report__list li::before {
  content: '';
  position: absolute;
  left: 0;
  top: 14px;
  width: 8px;
  height: 8px;
  border-radius: 50%;
  background: var(--accent);
  opacity: 0.6;
}

/* Figures */
.report__figure {
  margin: 32px 0;
  text-align: center;
}

.report__figure img {
  border-radius: var(--radius-md);
  border: 1px solid var(--border);
  max-width: 100%;
  opacity: 1;
  transition: opacity 0.4s ease;
}

.report__figure img[data-src] {
  opacity: 0;
  min-height: 200px;
  background: var(--bg-secondary);
  animation: shimmer 1.5s infinite;
}

.report__figure img.loaded {
  opacity: 1;
  min-height: auto;
  animation: none;
}

@keyframes shimmer {
  0%, 100% { opacity: 0.3; }
  50% { opacity: 0.6; }
}

.report__figure-caption {
  font-size: 13px;
  color: var(--text-tertiary);
  margin-top: 10px;
  font-style: italic;
}

/* Tables */
.report__table {
  width: 100%;
  border-collapse: collapse;
  margin: 24px 0;
  font-size: 14px;
  line-height: 1.6;
  border: 1px solid var(--border);
  border-radius: var(--radius-sm);
  overflow: hidden;
}

.report__table thead {
  background: var(--bg-secondary);
}

.report__table th {
  padding: 12px 16px;
  text-align: left;
  font-weight: 600;
  font-size: 13px;
  color: var(--text-secondary);
  text-transform: uppercase;
  letter-spacing: 0.04em;
  border-bottom: 2px solid var(--border-strong);
  white-space: nowrap;
}

.report__table td {
  padding: 10px 16px;
  border-bottom: 1px solid var(--border);
  color: var(--text-secondary);
  font-family: var(--font-sans);
}

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

.report__table tbody tr:hover {
  background: var(--accent-soft);
}

.report__table tbody tr.highlight {
  background: var(--accent-soft);
  font-weight: 600;
}

.report__table tbody tr.highlight td {
  color: var(--text-primary);
  font-weight: 600;
}

.report__table td:first-child {
  font-weight: 500;
  color: var(--text-primary);
}

/* Code Blocks */
.report__code {
  background: var(--code-bg);
  border-radius: var(--radius-sm);
  padding: 20px 24px;
  margin: 20px 0;
  overflow-x: auto;
  font-family: var(--font-mono);
  font-size: 14px;
  line-height: 1.6;
  color: var(--text-primary);
  border: 1px solid var(--border);
}

/* Author Info */
.report__authors-box {
  background: var(--bg-secondary);
  border-radius: var(--radius-md);
  padding: 24px;
  margin: 32px 0;
  border: 1px solid var(--border);
}

.report__authors-box h4 {
  font-size: 14px;
  font-weight: 600;
  color: var(--text-tertiary);
  text-transform: uppercase;
  letter-spacing: 0.06em;
  margin-bottom: 12px;
}

.report__author-list {
  display: flex;
  flex-wrap: wrap;
  gap: 8px;
}

.report__author-chip {
  display: inline-flex;
  align-items: center;
  gap: 6px;
  padding: 6px 14px;
  border-radius: 980px;
  background: var(--card-bg);
  border: 1px solid var(--border);
  font-size: 14px;
  color: var(--text-secondary);
}

/* Paper Link */
.report__paper-link {
  display: flex;
  align-items: center;
  gap: 16px;
  padding: 20px 24px;
  background: var(--bg-secondary);
  border-radius: var(--radius-md);
  border: 1px solid var(--border);
  margin: 32px 0;
  transition: all var(--transition);
}

.report__paper-link:hover {
  border-color: var(--accent);
  box-shadow: var(--shadow-md);
}

.report__paper-link-icon {
  width: 48px;
  height: 48px;
  border-radius: var(--radius-sm);
  background: var(--accent-soft);
  display: flex;
  align-items: center;
  justify-content: center;
  font-size: 24px;
  flex-shrink: 0;
}

.report__paper-link-info h4 {
  font-size: 15px;
  font-weight: 600;
  color: var(--text-primary);
  margin-bottom: 2px;
}

.report__paper-link-info p {
  font-size: 13px;
  color: var(--text-tertiary);
}

/* ===== Footer ===== */
.footer {
  border-top: 1px solid var(--border);
  padding: 40px 24px;
  text-align: center;
}

.footer__text {
  font-size: 13px;
  color: var(--text-tertiary);
  line-height: 1.6;
}

.footer__text a {
  color: var(--text-secondary);
}

.footer__powered {
  font-size: 12px;
  color: var(--text-tertiary);
  margin-top: 8px;
  opacity: 0.7;
}

/* ===== Animations ===== */
.fade-in {
  opacity: 0;
  transform: translateY(20px);
  transition: opacity 0.6s ease, transform 0.6s ease;
}

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

.stagger-1 { transition-delay: 0.05s; }
.stagger-2 { transition-delay: 0.1s; }
.stagger-3 { transition-delay: 0.15s; }
.stagger-4 { transition-delay: 0.2s; }
.stagger-5 { transition-delay: 0.25s; }
.stagger-6 { transition-delay: 0.3s; }

/* ===== Gradient Presets ===== */
.gradient-1 { background: linear-gradient(135deg, #667eea, #764ba2); }
.gradient-2 { background: linear-gradient(135deg, #f093fb, #f5576c); }
.gradient-3 { background: linear-gradient(135deg, #4facfe, #00f2fe); }
.gradient-4 { background: linear-gradient(135deg, #43e97b, #38f9d7); }
.gradient-5 { background: linear-gradient(135deg, #fa709a, #fee140); }
.gradient-6 { background: linear-gradient(135deg, #a18cd1, #fbc2eb); }
.gradient-7 { background: linear-gradient(135deg, #fccb90, #d57eeb); }
.gradient-8 { background: linear-gradient(135deg, #89f7fe, #66a6ff); }

/* ===== Responsive ===== */
@media (max-width: 768px) {
  .hero { padding: 120px 20px 60px; }
  .hero__stats { gap: 32px; }
  .reports__grid { grid-template-columns: 1fr; gap: 16px; }
  .report-card__header { height: 160px; }
  .report__meta { flex-direction: column; gap: 8px; }
  .report__meta-divider { display: none; }
  .report__content { padding: 24px 16px 80px; }
  .nav__actions { overflow-x: auto; -webkit-overflow-scrolling: touch; }
  .nav__link { white-space: nowrap; font-size: 13px; }
  .filters { padding: 0 16px 32px; }
  .filter-tag { font-size: 13px; padding: 6px 14px; }
}

@media (max-width: 480px) {
  .hero__title { font-size: 32px; }
  .report__title { font-size: 24px; }
  .report-card__body { padding: 16px; }
  .report-card__title { font-size: 16px; }
}

/* ===== Scrollbar ===== */
::-webkit-scrollbar { width: 8px; }
::-webkit-scrollbar-track { background: transparent; }
::-webkit-scrollbar-thumb {
  background: var(--border-strong);
  border-radius: 4px;
}
::-webkit-scrollbar-thumb:hover {
  background: var(--text-tertiary);
}

/* ===== Prev/Next Navigation ===== */
.report__nav-links {
  display: flex;
  justify-content: space-between;
  gap: 16px;
  margin-top: 48px;
  padding-top: 32px;
  border-top: 1px solid var(--border);
}

.report__nav-link {
  display: flex;
  flex-direction: column;
  gap: 4px;
  padding: 16px 20px;
  border-radius: var(--radius-md);
  background: var(--bg-secondary);
  border: 1px solid var(--border);
  text-decoration: none;
  transition: all var(--transition);
  max-width: 48%;
  min-width: 0;
}

.report__nav-link:hover {
  border-color: var(--accent);
  box-shadow: var(--shadow-md);
  transform: translateY(-2px);
}

.report__nav-link--next {
  text-align: right;
  margin-left: auto;
}

.report__nav-label {
  font-size: 12px;
  color: var(--text-tertiary);
  text-transform: uppercase;
  letter-spacing: 0.06em;
}

.report__nav-title {
  font-size: 14px;
  font-weight: 600;
  color: var(--text-primary);
  white-space: nowrap;
  overflow: hidden;
  text-overflow: ellipsis;
}


/* ===== Sidebar ===== */

/* ===== Footer Link Fix ===== */
.footer__text a{color:var(--accent);font-weight:600;transition:color .2s}
.footer__text a:hover{color:var(--accent-hover)}
.footer__text strong{font-weight:600}

.sidebar-overlay{display:none;position:fixed;inset:0;background:rgba(0,0,0,0.35);backdrop-filter:blur(4px);-webkit-backdrop-filter:blur(4px);z-index:850;opacity:0;transition:opacity .3s ease}
.sidebar-overlay.active{display:block;opacity:1}
.sidebar{position:fixed;top:52px;left:0;bottom:0;width:244px;background:rgba(249,249,251,0.82);backdrop-filter:saturate(180%) blur(20px);-webkit-backdrop-filter:saturate(180%) blur(20px);border-right:0.5px solid var(--border);z-index:900;overflow-y:auto;overflow-x:hidden;display:flex;flex-direction:column;transition:transform .3s ease}
[data-theme="dark"] .sidebar{background:rgba(17,17,17,0.82)}
.sidebar::-webkit-scrollbar{width:0}
.sidebar-logo{padding:16px 16px 12px;display:flex;align-items:center;gap:10px;border-bottom:0.5px solid var(--border);margin-bottom:4px}
.sidebar-logo-icon{width:30px;height:30px;border-radius:8px;background:linear-gradient(135deg,#667eea,#764ba2);display:flex;align-items:center;justify-content:center;color:#fff;font-size:12px;font-weight:700;flex-shrink:0}
.sidebar-logo-text{display:flex;flex-direction:column}
.sidebar-logo-title{font-size:14px;font-weight:600;color:var(--text-primary);letter-spacing:-0.01em}
.sidebar-logo-sub{font-size:10px;color:var(--text-tertiary);letter-spacing:0.02em}
.sidebar-section{margin:0 8px 2px}
.sidebar-section-header{display:flex;align-items:center;justify-content:space-between;width:100%;padding:8px 10px;border:none;background:transparent;cursor:pointer;border-radius:8px;font-family:var(--font-sans);transition:background .15s ease;user-select:none}
.sidebar-section-header:hover{background:var(--accent-soft)}
.sidebar-section-title{font-size:11px;font-weight:600;text-transform:uppercase;letter-spacing:0.06em;color:var(--text-tertiary);display:flex;align-items:center;gap:6px}
.sidebar-chevron{font-size:10px;color:var(--text-tertiary);transition:transform .25s cubic-bezier(0.32,0.72,0,1);flex-shrink:0}
.sidebar-section.collapsed .sidebar-chevron{transform:rotate(-90deg)}
.sidebar-section-body{padding:2px 4px 8px;transition:opacity .2s ease}
.sidebar-section.collapsed .sidebar-section-body{display:none}
.sidebar-link{display:flex;align-items:center;gap:8px;padding:7px 10px;border-radius:6px;font-size:13px;color:var(--text-secondary);transition:all .15s ease;text-decoration:none}
.sidebar-link:hover{background:var(--accent-soft);color:var(--text-primary)}
.sidebar-link-icon{font-size:14px;width:18px;text-align:center;flex-shrink:0}
.sidebar-focus-card{display:block;padding:14px 12px;border-radius:10px;background:linear-gradient(135deg,rgba(102,126,234,0.1),rgba(118,75,162,0.07));border:1px solid rgba(102,126,234,0.15);text-decoration:none;color:inherit;transition:all .25s cubic-bezier(0.32,0.72,0,1)}
.sidebar-focus-card:hover{transform:translateY(-1px);box-shadow:0 4px 16px rgba(102,126,234,0.12);border-color:rgba(102,126,234,0.3);color:inherit}
.sidebar-focus-card-title{font-size:13px;font-weight:600;color:var(--text-primary);margin-bottom:3px}
.sidebar-focus-card-desc{font-size:11px;color:var(--text-tertiary);line-height:1.3}
.sidebar-focus-card-arrow{font-size:11px;color:var(--accent);margin-top:6px;font-weight:500}
.sidebar-stats{margin-top:auto;padding:12px 16px;border-top:0.5px solid var(--border);display:flex;justify-content:space-between}
.sidebar-stat{text-align:center}
.sidebar-stat-val{font-size:16px;font-weight:700;color:var(--text-primary);letter-spacing:-0.02em}
.sidebar-stat-label{font-size:9px;color:var(--text-tertiary);text-transform:uppercase;letter-spacing:0.04em;margin-top:1px}
.sidebar-stats-item{text-align:center;padding:12px 8px;background:var(--bg-secondary);border-radius:8px}
.sidebar-link-count{display:inline-block;min-width:20px;padding:2px 6px;border-radius:10px;background:var(--bg-secondary);color:var(--text-secondary);font-size:11px;font-weight:500;text-align:center;line-height:1.4}
.nav-left{display:flex;align-items:center;gap:10px}
.nav__hamburger{display:none;width:32px;height:32px;border:none;background:transparent;cursor:pointer;padding:5px;flex-direction:column;justify-content:center;align-items:center;gap:4px;border-radius:6px}
.nav__hamburger span{display:block;width:18px;height:1.5px;background:var(--text-primary);border-radius:1px;transition:all .25s ease}
.nav__hamburger.active span:nth-child(1){transform:rotate(45deg) translate(3px,3px)}
.nav__hamburger.active span:nth-child(2){opacity:0}
.nav__hamburger.active span:nth-child(3){transform:rotate(-45deg) translate(3px,-3px)}
.page-with-sidebar{display:flex;min-height:calc(100vh - 52px)}
.main-content{flex:1;margin-left:244px;min-height:100vh;padding-top:52px}
.main-content .hero{padding-top:40px}
.main-content .reports{padding-left:32px;padding-right:32px}
.view-all-link{text-align:center;padding:16px 32px 60px}
.view-all-link a{display:inline-flex;align-items:center;gap:6px;font-size:14px;font-weight:500;color:var(--accent);padding:10px 24px;border-radius:980px;border:1px solid var(--accent);transition:all .2s ease}
.view-all-link a:hover{background:var(--accent);color:#fff}
.breadcrumb{display:inline-flex;align-items:center;gap:6px;font-size:13px;color:var(--text-tertiary);margin-bottom:8px}
.breadcrumb a{color:var(--accent)}
.phase-cards{max-width:800px;margin:0 auto;padding:0 24px 60px;display:grid;gap:20px}
.phase-card{display:block;background:var(--card-bg);border:1px solid var(--border);border-radius:16px;padding:28px;text-decoration:none;color:inherit;transition:all .3s cubic-bezier(0.25,0.1,0.25,1);position:relative;overflow:hidden}
.phase-card::before{content:'';position:absolute;top:0;left:0;right:0;height:4px;background:linear-gradient(135deg,#667eea,#764ba2,#f093fb)}
.phase-card:hover{transform:translateY(-3px);box-shadow:var(--shadow-lg);color:inherit}
.phase-card-header{display:flex;align-items:center;gap:12px;margin-bottom:16px}
.phase-card-icon{font-size:24px}
.phase-card-tag{font-size:11px;font-weight:600;text-transform:uppercase;letter-spacing:0.06em;color:var(--accent);background:var(--accent-soft);padding:4px 10px;border-radius:6px}
.phase-card-lock{position:absolute;top:14px;right:14px;font-size:12px;opacity:0.5}
.phase-card-title{font-size:18px;font-weight:700;color:var(--text-primary);margin-bottom:6px;letter-spacing:-0.02em}
.phase-card-desc{font-size:13px;color:var(--text-secondary);line-height:1.5;margin-bottom:14px}
.phase-card-topics{display:flex;flex-wrap:wrap;gap:6px;margin-bottom:16px}
.phase-card-topics span{font-size:11px;padding:4px 10px;border-radius:100px;background:var(--tag-bg);color:var(--tag-text)}
.phase-card-foot{display:flex;justify-content:space-between;align-items:center;padding-top:14px;border-top:0.5px solid var(--border);font-size:12px;color:var(--text-tertiary)}
.phase-card-foot-arrow{color:var(--accent);font-weight:500}
.litreview-cards{max-width:900px;margin:0 auto;padding:0 24px 60px;display:grid;gap:24px}
.litreview-card{display:block;background:var(--card-bg);border:1px solid var(--border);border-radius:20px;padding:0;text-decoration:none;color:inherit;transition:all .35s cubic-bezier(0.25,0.1,0.25,1);position:relative;overflow:hidden}
.litreview-card:hover{transform:translateY(-4px);box-shadow:var(--shadow-lg);color:inherit}
.litreview-card__gradient{height:6px;width:100%;border-radius:20px 20px 0 0}
.litreview-card__gradient--1{background:linear-gradient(135deg,#667eea,#764ba2,#f093fb)}
.litreview-card__gradient--2{background:linear-gradient(135deg,#f093fb,#f5576c,#ff9a9e)}
.litreview-card__gradient--3{background:linear-gradient(135deg,#43e97b,#38f9d7,#667eea)}
.litreview-card__header{display:flex;align-items:center;gap:14px;padding:24px 28px 0}
.litreview-card__icon{font-size:32px;line-height:1}
.litreview-card__tag{font-size:11px;font-weight:700;text-transform:uppercase;letter-spacing:0.08em;color:var(--accent);background:var(--accent-soft);padding:5px 12px;border-radius:8px}
.litreview-card__title{font-size:20px;font-weight:700;color:var(--text-primary);margin:14px 28px 8px;letter-spacing:-0.02em;line-height:1.3}
.litreview-card__desc{font-size:14px;color:var(--text-secondary);line-height:1.6;margin:0 28px 16px}
.litreview-card__topics{display:flex;flex-direction:column;gap:10px;padding:0 28px 18px}
.litreview-card__topic-group{display:flex;flex-direction:column;gap:4px}
.litreview-card__topic-group-label{font-size:10px;font-weight:700;color:var(--text-tertiary);letter-spacing:0.04em;text-transform:uppercase}
.litreview-card__topic-group-items{display:flex;flex-wrap:wrap;gap:4px}
.litreview-card__topic{font-size:11px;padding:4px 10px;border-radius:100px;background:var(--tag-bg);color:var(--tag-text);white-space:nowrap}
.litreview-card__footer{display:flex;justify-content:space-between;align-items:center;padding:16px 28px;border-top:0.5px solid var(--border);font-size:13px;color:var(--text-tertiary)}
.litreview-card__stat{display:flex;flex-direction:column;align-items:center;gap:2px}
.litreview-card__stat-value{font-size:16px;font-weight:700;color:var(--text-primary)}
.litreview-card__stat-label{font-size:11px;color:var(--text-tertiary)}
.litreview-card__enter{color:var(--accent);font-weight:600;font-size:13px;transition:transform .2s}
.litreview-card:hover .litreview-card__enter{transform:translateX(4px)}
.empty-state{text-align:center;padding:80px 24px;color:var(--text-tertiary)}
.empty-state-icon{font-size:48px;margin-bottom:16px;opacity:0.5}
.empty-state h3{font-size:18px;font-weight:600;color:var(--text-secondary);margin-bottom:8px}
.empty-state p{font-size:14px;color:var(--text-tertiary);line-height:1.6}

@media(max-width:768px){
  .sidebar{transform:translateX(-100%);width:280px;top:0;z-index:950;box-shadow:var(--shadow-xl)}
  .sidebar.open{transform:translateX(0)}
  .sidebar-overlay{display:block}
  .page-with-sidebar{display:block}
  .main-content{margin-left:0}
  .main-content .reports{padding-left:16px;padding-right:16px}
  .nav__hamburger{display:flex}
}

/* ===== Additional Breakpoints ===== */
@media (max-width: 1024px) {
  .reports__grid { grid-template-columns: repeat(auto-fill, minmax(300px, 1fr)); }
  .main-content .reports { padding-left: 24px; padding-right: 24px; }
  .hero__stats { gap: 32px; }
}

/* ===== Skip to Content ===== */
.skip-to-content {
  position: absolute;
  left: -9999px;
  z-index: 999;
  padding: 8px 16px;
  background: var(--accent);
  color: #fff;
  border-radius: 4px;
  font-size: 14px;
  text-decoration: none;
}
.skip-to-content:focus {
  left: 16px;
  top: 8px;
}

/* ===== Focus styles for better accessibility ===== */
a:focus-visible,
button:focus-visible {
  outline: 2px solid var(--accent);
  outline-offset: 2px;
}

/* ===== Reduce motion for users who prefer it ===== */
@media (prefers-reduced-motion: reduce) {
  *, *::before, *::after {
    animation: none !important;
    transition: none !important;
  }
}

/* ===== Print ===== */
@media print {
  .nav, .footer, .theme-toggle, .filters, .sidebar, .sidebar-overlay { display: none; }
  body { background: #fff; color: #000; }
  .report-card { break-inside: avoid; }
}