/* HF Data Library — hfdatalibrary.com
   Academic data platform for high-frequency finance research
   Author: Ahmed Elkassabgi, University of Central Arkansas */

:root {
  --navy: #1a2332;
  --navy-light: #243044;
  --blue: #2563eb;
  --blue-light: #3b82f6;
  --blue-pale: #eff6ff;
  --gold: #d4a843;
  --gold-light: #f0d78c;
  --gray-50: #f9fafb;
  --gray-100: #f3f4f6;
  --gray-200: #e5e7eb;
  --gray-300: #d1d5db;
  --gray-400: #9ca3af;
  --gray-500: #6b7280;
  --gray-600: #4b5563;
  --gray-700: #374151;
  --gray-800: #1f2937;
  --gray-900: #111827;
  --green: #059669;
  --red: #dc2626;
  --font-serif: "Georgia", "Times New Roman", serif;
  --font-sans: "Inter", -apple-system, BlinkMacSystemFont, "Segoe UI", sans-serif;
  --font-mono: "JetBrains Mono", "Fira Code", "Consolas", monospace;
  --max-width: 1200px;
  --shadow-sm: 0 1px 2px rgba(0,0,0,0.05);
  --shadow: 0 1px 3px rgba(0,0,0,0.1), 0 1px 2px rgba(0,0,0,0.06);
  --shadow-md: 0 4px 6px rgba(0,0,0,0.07), 0 2px 4px rgba(0,0,0,0.06);
  --shadow-lg: 0 10px 15px rgba(0,0,0,0.1), 0 4px 6px rgba(0,0,0,0.05);
  --radius: 8px;
  --radius-lg: 12px;
}

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

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

body {
  font-family: var(--font-sans);
  color: var(--gray-800);
  line-height: 1.7;
  background: #fff;
  -webkit-font-smoothing: antialiased;
}

/* ── Typography ── */
h1, h2, h3, h4, h5, h6 {
  font-family: var(--font-serif);
  color: var(--navy);
  line-height: 1.3;
  font-weight: 700;
}
h1 { font-size: 2.5rem; }
h2 { font-size: 1.875rem; margin-bottom: 1rem; }
h3 { font-size: 1.375rem; margin-bottom: 0.75rem; }
h4 { font-size: 1.125rem; margin-bottom: 0.5rem; }

p { margin-bottom: 1rem; }
a { color: var(--blue); text-decoration: none; transition: color 0.15s; }
a:hover { color: var(--blue-light); }

code {
  font-family: var(--font-mono);
  font-size: 0.875em;
  background: var(--gray-100);
  padding: 0.15em 0.4em;
  border-radius: 4px;
}
pre {
  background: var(--navy);
  color: #e2e8f0;
  padding: 1.25rem 1.5rem;
  border-radius: var(--radius);
  overflow-x: auto;
  font-size: 0.875rem;
  line-height: 1.6;
  margin-bottom: 1.5rem;
}
pre code { background: none; padding: 0; color: inherit; }

/* ── Layout ── */
.container { max-width: var(--max-width); margin: 0 auto; padding: 0 1.5rem; }
.section { padding: 5rem 0; }
.section-alt { background: var(--gray-50); }

/* ── Status Bar ── */
.status-bar {
  background: var(--gray-50);
  border-bottom: 1px solid var(--gray-200);
  font-size: 0.8rem;
  color: var(--gray-500);
  height: 32px;
  line-height: 32px;
}

/* ── Navigation ── */
.navbar {
  background: var(--navy);
  position: sticky;
  top: 0;
  z-index: 100;
  box-shadow: 0 2px 8px rgba(0,0,0,0.15);
}
.navbar .container {
  display: flex;
  align-items: center;
  justify-content: space-between;
  height: 64px;
}
.navbar-brand {
  display: flex;
  align-items: center;
  gap: 0.75rem;
  color: #fff;
  font-family: var(--font-serif);
  font-size: 1.25rem;
  font-weight: 700;
  text-decoration: none;
}
.navbar-brand span { color: var(--gold); }
.nav-links { display: flex; gap: 0.25rem; list-style: none; }
.nav-links a {
  color: rgba(255,255,255,0.8);
  padding: 0.5rem 0.875rem;
  border-radius: 6px;
  font-size: 0.9rem;
  font-weight: 500;
  transition: all 0.15s;
}
.nav-links a:hover, .nav-links a.active {
  color: #fff;
  background: rgba(255,255,255,0.1);
}
.nav-toggle { display: none; background: none; border: none; color: #fff; font-size: 1.5rem; cursor: pointer; }

/* ── Hero ── */
.hero {
  background: linear-gradient(135deg, var(--navy) 0%, var(--navy-light) 100%);
  color: #fff;
  padding: 6rem 0 5rem;
  text-align: center;
}
.hero h1 {
  color: #fff;
  font-size: 3rem;
  margin-bottom: 0.5rem;
}
.hero h1 span { color: var(--gold); }
.hero .subtitle {
  font-size: 1.25rem;
  color: rgba(255,255,255,0.75);
  max-width: 700px;
  margin: 0 auto 2.5rem;
  font-weight: 400;
}

/* ── Stats bar ── */
.stats-bar {
  display: grid;
  grid-template-columns: repeat(4, 1fr);
  gap: 1.5rem;
  max-width: 900px;
  margin: 0 auto 3rem;
}
.stat-item {
  text-align: center;
}
.stat-number {
  font-family: var(--font-mono);
  font-size: 2rem;
  font-weight: 700;
  color: var(--gold);
  display: block;
}
.stat-label {
  font-size: 0.85rem;
  color: rgba(255,255,255,0.6);
  text-transform: uppercase;
  letter-spacing: 0.05em;
}

/* ── Buttons ── */
.btn {
  display: inline-flex;
  align-items: center;
  gap: 0.5rem;
  padding: 0.75rem 1.75rem;
  border-radius: var(--radius);
  font-weight: 600;
  font-size: 0.95rem;
  cursor: pointer;
  border: none;
  transition: all 0.2s;
  text-decoration: none;
}
.btn-primary { background: var(--blue); color: #fff; }
.btn-primary:hover { background: var(--blue-light); color: #fff; transform: translateY(-1px); box-shadow: var(--shadow-md); }
.btn-outline { background: transparent; color: #fff; border: 2px solid rgba(255,255,255,0.3); }
.btn-outline:hover { border-color: #fff; color: #fff; }
.btn-gold { background: var(--gold); color: var(--navy); }
.btn-gold:hover { background: var(--gold-light); color: var(--navy); }
.btn-group { display: flex; gap: 1rem; justify-content: center; flex-wrap: wrap; }

/* ── Cards ── */
.card {
  background: #fff;
  border: 1px solid var(--gray-200);
  border-radius: var(--radius-lg);
  padding: 2rem;
  transition: all 0.2s;
}
.card:hover { box-shadow: var(--shadow-md); border-color: var(--gray-300); }
.card-icon {
  width: 48px;
  height: 48px;
  background: var(--blue-pale);
  border-radius: 10px;
  display: flex;
  align-items: center;
  justify-content: center;
  font-size: 1.5rem;
  margin-bottom: 1rem;
}
.card h3 { font-family: var(--font-sans); font-size: 1.125rem; }
.card p { color: var(--gray-600); font-size: 0.95rem; margin-bottom: 0; }

.grid-2 { display: grid; grid-template-columns: repeat(2, 1fr); gap: 1.5rem; }
.grid-3 { display: grid; grid-template-columns: repeat(3, 1fr); gap: 1.5rem; }
.grid-4 { display: grid; grid-template-columns: repeat(4, 1fr); gap: 1.5rem; }

/* ── Data versions ── */
.version-card {
  border-left: 4px solid var(--blue);
  padding-left: 1.5rem;
}
.version-card.raw { border-color: var(--gray-400); }
.version-card.clean { border-color: var(--blue); }
.version-card.filled { border-color: var(--green); }
.version-card.academic { border-color: var(--gold); }
.version-tag {
  display: inline-block;
  font-size: 0.75rem;
  font-weight: 700;
  text-transform: uppercase;
  letter-spacing: 0.05em;
  padding: 0.2em 0.6em;
  border-radius: 4px;
  margin-bottom: 0.5rem;
}
.version-tag.raw { background: var(--gray-100); color: var(--gray-600); }
.version-tag.clean { background: var(--blue-pale); color: var(--blue); }
.version-tag.filled { background: #ecfdf5; color: var(--green); }
.version-tag.academic { background: #fef9ee; color: #92600a; }

/* ── Tables ── */
.table-wrap { overflow-x: auto; margin-bottom: 1.5rem; }
table {
  width: 100%;
  border-collapse: collapse;
  font-size: 0.9rem;
}
thead th {
  text-align: left;
  padding: 0.75rem 1rem;
  border-bottom: 2px solid var(--gray-300);
  font-weight: 600;
  color: var(--gray-700);
  white-space: nowrap;
}
tbody td {
  padding: 0.625rem 1rem;
  border-bottom: 1px solid var(--gray-200);
}
tbody tr:hover { background: var(--gray-50); }
td.mono { font-family: var(--font-mono); font-size: 0.85rem; }

/* ── Citation block ── */
.citation-block {
  background: var(--gray-50);
  border: 1px solid var(--gray-200);
  border-radius: var(--radius);
  padding: 1.25rem 1.5rem;
  position: relative;
  font-size: 0.9rem;
  margin-bottom: 1rem;
}
.citation-block .copy-btn {
  position: absolute;
  top: 0.75rem;
  right: 0.75rem;
  background: var(--blue);
  color: #fff;
  border: none;
  padding: 0.35rem 0.75rem;
  border-radius: 4px;
  font-size: 0.8rem;
  cursor: pointer;
}
.citation-block .copy-btn:hover { background: var(--blue-light); }

/* ── Tabs ── */
.tab-nav { display: flex; gap: 0; border-bottom: 2px solid var(--gray-200); margin-bottom: 1.5rem; }
.tab-nav button {
  background: none;
  border: none;
  padding: 0.75rem 1.25rem;
  font-size: 0.9rem;
  font-weight: 500;
  color: var(--gray-500);
  cursor: pointer;
  border-bottom: 2px solid transparent;
  margin-bottom: -2px;
  transition: all 0.15s;
}
.tab-nav button:hover { color: var(--gray-700); }
.tab-nav button.active { color: var(--blue); border-bottom-color: var(--blue); }
.tab-content { display: none; }
.tab-content.active { display: block; }

/* ── Feature highlight ── */
.feature-row {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: 4rem;
  align-items: center;
  margin-bottom: 4rem;
}
.feature-row.reverse { direction: rtl; }
.feature-row.reverse > * { direction: ltr; }
.feature-text h2 { margin-bottom: 0.75rem; }
.feature-text p { color: var(--gray-600); }
.feature-visual {
  background: var(--gray-50);
  border: 1px solid var(--gray-200);
  border-radius: var(--radius-lg);
  padding: 2rem;
}

/* ── Comparison table ── */
.comparison-check { color: var(--green); font-weight: 700; }
.comparison-x { color: var(--gray-300); }
.comparison-highlight { background: var(--blue-pale) !important; }

/* ── Footer ── */
.footer {
  background: var(--navy);
  color: rgba(255,255,255,0.7);
  padding: 3rem 0 2rem;
  font-size: 0.9rem;
}
.footer-grid {
  display: grid;
  grid-template-columns: 2fr 1fr 1fr 1fr;
  gap: 2rem;
  margin-bottom: 2rem;
}
.footer h4 { color: #fff; font-family: var(--font-sans); margin-bottom: 0.75rem; }
.footer a { color: rgba(255,255,255,0.7); }
.footer a:hover { color: #fff; }
.footer ul { list-style: none; }
.footer li { margin-bottom: 0.4rem; }
.footer-bottom {
  border-top: 1px solid rgba(255,255,255,0.1);
  padding-top: 1.5rem;
  display: flex;
  justify-content: space-between;
  align-items: center;
}
.footer-bottom .orcid { font-family: var(--font-mono); font-size: 0.8rem; }

/* ── Responsive ── */
@media (max-width: 768px) {
  .hero h1 { font-size: 2rem; }
  .stats-bar { grid-template-columns: repeat(2, 1fr); gap: 1rem; }
  .stat-number { font-size: 1.5rem; }
  .grid-2, .grid-3, .grid-4 { grid-template-columns: 1fr; }
  .feature-row, .feature-row.reverse { grid-template-columns: 1fr; gap: 2rem; direction: ltr; }
  .footer-grid { grid-template-columns: 1fr 1fr; }
  .nav-links { display: none; }
  .nav-links.open {
    display: flex;
    flex-direction: column;
    position: absolute;
    top: 64px;
    left: 0;
    right: 0;
    background: var(--navy);
    padding: 1rem;
    box-shadow: var(--shadow-lg);
  }
  .nav-toggle { display: block; }
  .footer-bottom { flex-direction: column; gap: 0.5rem; text-align: center; }
}