/* ═══════════════════════════════════════════════════════════════════
   Helios GCS — Website Styles
   Dark theme: #0D1117 bg, #58A6FF accent
   ═══════════════════════════════════════════════════════════════════ */

:root {
  --bg: #0D1117;
  --surface: #161B22;
  --surface-light: #21262D;
  --surface-dim: #010409;
  --border: #30363D;
  --border-light: #3D444D;
  --text-primary: #E6EDF3;
  --text-secondary: #8B949E;
  --text-tertiary: #6E7681;
  --accent: #58A6FF;
  --accent-dim: #1F6FEB;
  --success: #3FB950;
  --warning: #D29922;
  --danger: #F85149;
  --font-sans: -apple-system, BlinkMacSystemFont, 'Segoe UI', Helvetica, Arial, sans-serif;
  --font-mono: 'SF Mono', SFMono-Regular, Consolas, 'Liberation Mono', Menlo, monospace;
  --max-width: 1200px;
  --sidebar-width: 240px;
  --toc-width: 200px;
}

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

body {
  font-family: var(--font-sans);
  background: var(--bg);
  color: var(--text-primary);
  font-size: 16px;
  line-height: 1.65;
  -webkit-font-smoothing: antialiased;
}

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

/* ─── Navigation ─────────────────────────────────────────────────── */

.nav {
  position: fixed;
  top: 0; left: 0; right: 0;
  height: 56px;
  background: rgba(1, 4, 9, 0.85);
  border-bottom: 1px solid var(--border);
  z-index: 100;
  backdrop-filter: blur(12px);
  -webkit-backdrop-filter: blur(12px);
}

.nav-inner {
  max-width: 1600px;
  margin: 0 auto;
  height: 100%;
  display: flex;
  align-items: center;
  padding: 0 24px;
  gap: 28px;
}

.nav-brand {
  display: flex;
  align-items: center;
  gap: 10px;
  font-weight: 700;
  font-size: 18px;
  color: var(--text-primary);
  letter-spacing: -0.02em;
  margin-right: 4px;
}

.nav-brand img { width: 32px; height: 32px; }
.nav-brand:hover { text-decoration: none; }

.nav-links {
  display: flex;
  align-items: center;
  gap: 20px;
  list-style: none;
  flex: 1;
  justify-content: center;
}

.nav-links li {
  display: flex;
  align-items: center;
}

.nav-links a {
  color: var(--text-secondary);
  font-size: 14px;
  font-weight: 500;
  transition: color 0.15s;
}

.nav-links a:hover, .nav-links a.active {
  color: var(--text-primary);
  text-decoration: none;
}

/* Download dropdown */
.nav-download {
  position: relative;
  display: flex;
  align-items: center;
}

.nav-download-btn {
  display: inline-flex;
  align-items: center;
  gap: 5px;
  color: var(--text-secondary);
  font-size: 14px;
  font-weight: 500;
  cursor: pointer;
  background: none;
  border: none;
  padding: 0;
  margin: 0;
  font-family: inherit;
  line-height: 1;
  transition: color 0.15s;
}

.nav-download-btn:hover { color: var(--text-primary); }

.nav-download-btn svg {
  width: 12px;
  height: 12px;
  fill: currentColor;
  transition: transform 0.15s;
}

.nav-download-menu {
  display: none;
  position: absolute;
  top: 100%;
  left: 50%;
  transform: translateX(-50%);
  padding-top: 8px;
  min-width: 180px;
}

.nav-download-menu-inner {
  background: var(--surface);
  border: 1px solid var(--border);
  border-radius: 8px;
  padding: 6px;
  box-shadow: 0 8px 24px rgba(0, 0, 0, 0.4);
}

.nav-download:hover .nav-download-menu { display: block; }
.nav-download:hover .nav-download-btn svg { transform: rotate(180deg); }

.nav-download-menu a {
  display: flex;
  align-items: center;
  gap: 8px;
  padding: 8px 12px;
  border-radius: 6px;
  font-size: 13px;
  color: var(--text-secondary);
}

.nav-download-menu a:hover {
  background: var(--surface-light);
  color: var(--text-primary);
  text-decoration: none;
}

.nav-download-menu a svg { width: 16px; height: 16px; fill: none; stroke: currentColor; stroke-width: 1.5; }

.nav-right {
  margin-left: auto;
  display: flex;
  align-items: center;
  gap: 16px;
}

.nav-github {
  color: var(--text-secondary);
  display: flex;
  align-items: center;
}

.nav-github:hover { color: var(--text-primary); text-decoration: none; }
.nav-github svg { width: 22px; height: 22px; fill: currentColor; }

/* ─── Splash Screen ─────────────────────────────────────────────── */

.splash {
  position: fixed;
  inset: 0;
  background: var(--bg);
  z-index: 9999;
  display: flex;
  align-items: center;
  justify-content: center;
}

.splash-inner {
  display: flex;
  flex-direction: column;
  align-items: center;
}

.splash-text {
  margin-top: 32px;
  text-align: center;
  opacity: 0;
}

.splash-title {
  color: var(--accent);
  font-size: 28px;
  font-weight: 300;
  letter-spacing: 14px;
  text-indent: 14px;
}

.splash-sub {
  color: rgba(88, 166, 255, 0.45);
  font-size: 10px;
  font-weight: 400;
  letter-spacing: 4px;
  text-indent: 4px;
  margin-top: 6px;
}

body.splash-active { overflow: hidden; }

/* ─── Hero ───────────────────────────────────────────────────────── */

.hero {
  padding: 160px 24px 80px;
  text-align: center;
  position: relative;
  overflow: hidden;
}

.hero::before {
  content: '';
  position: absolute;
  top: 40px; left: 50%;
  transform: translateX(-50%);
  width: 800px; height: 500px;
  background: radial-gradient(ellipse at center, rgba(88, 166, 255, 0.08) 0%, transparent 70%);
  pointer-events: none;
}

.hero-logo { width: 64px; height: 64px; margin-bottom: 20px; opacity: 0.9; }
.hero-logo-lg { width: 96px; height: 96px; margin-bottom: 28px; }

.hero h1 {
  font-size: 56px;
  font-weight: 700;
  line-height: 1.1;
  margin-bottom: 12px;
  letter-spacing: -0.03em;
}

.hero h1 span { color: var(--accent); font-weight: 400; }

.hero-subtitle {
  font-size: 18px;
  color: var(--accent);
  opacity: 0.6;
  font-weight: 500;
  letter-spacing: 0.04em;
  margin-bottom: 20px;
}

.hero-tagline {
  font-size: 19px;
  color: var(--text-tertiary);
  max-width: 560px;
  margin: 0 auto 40px;
  line-height: 1.65;
}

.hero-actions {
  display: flex;
  justify-content: center;
  gap: 12px;
  flex-wrap: wrap;
  margin-bottom: 36px;
}

.hero-meta {
  display: flex;
  justify-content: center;
  align-items: center;
  gap: 14px;
  font-family: var(--font-mono);
  font-size: 13px;
  color: var(--text-tertiary);
}

.hero-meta .dot {
  width: 3px; height: 3px;
  border-radius: 50%;
  background: var(--border-light);
  display: inline-block;
}

.btn {
  display: inline-flex;
  align-items: center;
  gap: 8px;
  padding: 11px 22px;
  border-radius: 6px;
  font-size: 15px;
  font-weight: 600;
  border: none;
  cursor: pointer;
  transition: all 0.15s;
}

.btn-primary { background: var(--accent-dim); color: var(--text-primary); }
.btn-primary:hover { background: var(--accent); color: var(--bg); text-decoration: none; }
.btn-secondary { background: transparent; color: var(--text-secondary); border: 1px solid var(--border); }
.btn-secondary:hover { border-color: var(--border-light); color: var(--text-primary); text-decoration: none; }

/* ─── Download / Install Section ─────────────────────────────────── */

.download-section {
  max-width: var(--max-width);
  margin: 0 auto;
  padding: 48px 24px;
}

.download-tabs {
  display: flex;
  gap: 0;
  border-bottom: 1px solid var(--border);
  margin-bottom: 28px;
}

.download-tab {
  padding: 10px 20px;
  font-size: 14px;
  font-weight: 500;
  color: var(--text-tertiary);
  cursor: pointer;
  border-bottom: 2px solid transparent;
  margin-bottom: -1px;
  background: none;
  border-top: none;
  border-left: none;
  border-right: none;
  font-family: inherit;
  transition: color 0.15s;
}

.download-tab:hover { color: var(--text-secondary); }
.download-tab.active { color: var(--accent); border-bottom-color: var(--accent); }

.download-panel { display: none; }
.download-panel.active { display: block; }

.download-panel h3 {
  font-size: 18px;
  font-weight: 600;
  margin-bottom: 12px;
}

.download-panel p {
  color: var(--text-secondary);
  margin-bottom: 16px;
  font-size: 15px;
  line-height: 1.6;
}

.download-panel pre {
  background: var(--surface);
  border: 1px solid var(--border);
  border-radius: 8px;
  padding: 16px 20px;
  font-family: var(--font-mono);
  font-size: 14px;
  line-height: 1.6;
  color: var(--text-primary);
  overflow-x: auto;
  margin-bottom: 16px;
}

.download-panel .download-comment { color: var(--text-tertiary); }

.download-btn {
  display: inline-flex;
  align-items: center;
  gap: 8px;
  padding: 12px 24px;
  background: var(--accent-dim);
  color: var(--text-primary);
  border-radius: 8px;
  font-size: 15px;
  font-weight: 600;
  transition: background 0.15s;
}

.download-btn:hover { background: var(--accent); color: var(--bg); text-decoration: none; }

.download-btn svg { width: 18px; height: 18px; fill: none; stroke: currentColor; stroke-width: 1.5; }

/* ─── Features Grid ──────────────────────────────────────────────── */

.section {
  max-width: var(--max-width);
  margin: 0 auto;
  padding: 56px 24px;
}

.section-title {
  font-size: 22px;
  font-weight: 600;
  margin-bottom: 28px;
  color: var(--text-secondary);
}

.features-grid {
  display: grid;
  grid-template-columns: repeat(3, 1fr);
  gap: 1px;
  background: var(--border);
  border: 1px solid var(--border);
  border-radius: 12px;
  overflow: hidden;
}

.feature-card {
  display: block;
  background: var(--surface);
  padding: 28px;
  transition: background 0.15s;
  color: inherit;
}

.feature-card:hover { background: var(--surface-light); text-decoration: none; }

.feature-header {
  display: flex;
  align-items: center;
  gap: 10px;
  margin-bottom: 10px;
}

.feature-svg { color: var(--accent); flex-shrink: 0; }

.feature-card h3 { font-size: 15px; font-weight: 600; color: var(--text-primary); }

.feature-card p {
  font-size: 14px;
  color: var(--text-tertiary);
  line-height: 1.55;
  margin: 0;
}

/* ─── Why Helios ────────────────────────────────────────────────── */

.why-intro {
  font-size: 17px;
  color: var(--text-secondary);
  max-width: 640px;
  line-height: 1.65;
  margin-bottom: 32px;
}

.why-grid {
  display: grid;
  grid-template-columns: repeat(2, 1fr);
  gap: 20px;
}

.why-card {
  background: var(--surface);
  border: 1px solid var(--border);
  border-radius: 10px;
  padding: 28px;
}

.why-icon {
  color: var(--accent);
  margin-bottom: 14px;
}

.why-card h3 {
  font-size: 16px;
  font-weight: 600;
  margin-bottom: 8px;
  color: var(--text-primary);
}

.why-card p {
  font-size: 14px;
  color: var(--text-tertiary);
  line-height: 1.6;
  margin: 0;
}

@media (max-width: 768px) {
  .why-grid { grid-template-columns: 1fr; }
}

/* ─── Compatibility ──────────────────────────────────────────────── */

.compat-section { padding-top: 0; }

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

.compat-grid h4 {
  font-size: 12px;
  font-weight: 700;
  text-transform: uppercase;
  letter-spacing: 0.08em;
  color: var(--text-tertiary);
  margin-bottom: 14px;
}

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

.compat-list li {
  display: flex;
  align-items: center;
  gap: 10px;
  font-size: 14px;
  color: var(--text-secondary);
  padding: 5px 0;
}

.compat-dot { width: 6px; height: 6px; border-radius: 50%; flex-shrink: 0; }
.compat-dot.green { background: var(--success); }
.compat-dot.amber { background: var(--warning); }

.compat-tag {
  font-family: var(--font-mono);
  font-size: 11px;
  color: var(--text-tertiary);
  background: var(--surface-light);
  padding: 2px 7px;
  border-radius: 3px;
  margin-left: auto;
}

.compat-note {
  font-size: 12px;
  color: var(--text-tertiary);
  font-style: italic;
  margin-left: auto;
}

/* ─── Footer ─────────────────────────────────────────────────────── */

.footer {
  padding: 32px 24px;
  border-top: 1px solid var(--border);
  text-align: center;
  color: var(--text-tertiary);
  font-size: 13px;
}

.footer a { color: var(--text-tertiary); }
.footer a:hover { color: var(--text-secondary); }

/* ─── Docs Layout ────────────────────────────────────────────────── */

.docs-layout {
  display: flex;
  max-width: 1600px;
  margin: 56px auto 0;
  min-height: calc(100vh - 56px);
}

.docs-sidebar {
  width: var(--sidebar-width);
  min-width: var(--sidebar-width);
  border-right: 1px solid var(--border);
  padding: 24px 16px;
  position: sticky;
  top: 56px;
  height: calc(100vh - 56px);
  overflow-y: auto;
}

.docs-sidebar h4 {
  font-size: 11px;
  font-weight: 700;
  text-transform: uppercase;
  letter-spacing: 0.08em;
  color: var(--text-tertiary);
  margin: 20px 0 8px;
  padding: 0 8px;
}

.docs-sidebar h4:first-child { margin-top: 0; }

.docs-sidebar a {
  display: block;
  padding: 6px 8px;
  border-radius: 6px;
  font-size: 14px;
  color: var(--text-secondary);
  transition: all 0.1s;
}

.docs-sidebar a:hover {
  background: var(--surface-light);
  color: var(--text-primary);
  text-decoration: none;
}

.docs-sidebar a.active {
  background: rgba(88, 166, 255, 0.1);
  color: var(--accent);
}

.docs-content {
  flex: 1;
  padding: 40px 56px 80px;
  max-width: 900px;
  min-width: 0;
}

/* ─── Right TOC ──────────────────────────────────────────────────── */

.docs-toc {
  width: var(--toc-width);
  min-width: var(--toc-width);
  padding: 24px 16px;
  position: sticky;
  top: 56px;
  height: calc(100vh - 56px);
  overflow-y: auto;
  border-left: 1px solid var(--border);
}

.docs-toc h4 {
  font-size: 11px;
  font-weight: 700;
  text-transform: uppercase;
  letter-spacing: 0.08em;
  color: var(--text-tertiary);
  margin: 0 0 10px;
  padding: 0 6px;
}

.docs-toc a {
  display: block;
  padding: 3px 6px;
  border-radius: 4px;
  font-size: 13px;
  color: var(--text-tertiary);
  line-height: 1.45;
  transition: color 0.1s;
  border-left: 2px solid transparent;
  margin-left: -2px;
}

.docs-toc a:hover { color: var(--text-secondary); text-decoration: none; }
.docs-toc a.active { color: var(--accent); border-left-color: var(--accent); }
.docs-toc a.toc-h3 { padding-left: 16px; font-size: 12px; }

/* ─── Markdown Content ───────────────────────────────────────────── */

.docs-content h1 {
  font-size: 32px;
  font-weight: 700;
  margin-bottom: 8px;
  padding-bottom: 12px;
  border-bottom: 1px solid var(--border);
}

.docs-content h2 {
  font-size: 24px;
  font-weight: 600;
  margin-top: 48px;
  margin-bottom: 16px;
  padding-bottom: 8px;
  border-bottom: 1px solid var(--border);
}

.docs-content h3 {
  font-size: 18px;
  font-weight: 600;
  margin-top: 32px;
  margin-bottom: 12px;
}

.docs-content p {
  margin-bottom: 16px;
  color: var(--text-secondary);
  font-size: 15px;
}

.docs-content ul, .docs-content ol {
  margin-bottom: 16px;
  padding-left: 24px;
}

.docs-content li {
  margin-bottom: 6px;
  color: var(--text-secondary);
  font-size: 15px;
}

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

.docs-content code {
  font-family: var(--font-mono);
  font-size: 0.88em;
  background: var(--surface-light);
  padding: 2px 6px;
  border-radius: 4px;
  border: 1px solid var(--border);
}

.docs-content pre {
  background: var(--surface);
  border: 1px solid var(--border);
  border-radius: 8px;
  padding: 16px 20px;
  overflow-x: auto;
  margin-bottom: 20px;
}

.docs-content pre code {
  background: none;
  border: none;
  padding: 0;
  font-size: 14px;
  line-height: 1.55;
}

.docs-content table {
  width: 100%;
  border-collapse: collapse;
  margin-bottom: 20px;
  font-size: 14px;
}

.docs-content th {
  text-align: left;
  padding: 10px 12px;
  border-bottom: 2px solid var(--border);
  color: var(--text-secondary);
  font-weight: 600;
  font-size: 13px;
}

.docs-content td {
  padding: 8px 12px;
  border-bottom: 1px solid var(--border);
  font-size: 14px;
}

.docs-content hr {
  border: none;
  border-top: 1px solid var(--border);
  margin: 32px 0;
}

.docs-content blockquote {
  border-left: 3px solid var(--accent);
  padding: 12px 16px;
  margin: 16px 0;
  background: rgba(88, 166, 255, 0.05);
  border-radius: 0 8px 8px 0;
}

.docs-content blockquote p { margin: 0; color: var(--text-secondary); }

/* ─── Mobile ─────────────────────────────────────────────────────── */

.menu-toggle {
  display: none;
  background: none;
  border: none;
  color: var(--text-primary);
  font-size: 24px;
  cursor: pointer;
  padding: 4px;
}

@media (max-width: 1024px) {
  .docs-toc { display: none; }
}

@media (max-width: 768px) {
  .hero { padding: 120px 24px 50px; }
  .hero h1 { font-size: 36px; }
  .hero-logo-lg { width: 72px; height: 72px; margin-bottom: 20px; }
  .hero-subtitle { font-size: 15px; margin-bottom: 14px; }
  .hero-tagline { font-size: 16px; }
  .features-grid { grid-template-columns: 1fr; }
  .compat-grid { grid-template-columns: 1fr; gap: 24px; }
  .download-tabs { overflow-x: auto; }
  .hero-meta { flex-wrap: wrap; gap: 8px; }

  .menu-toggle { display: block; }

  .nav-links {
    display: none;
    position: fixed;
    top: 56px;
    left: 0;
    right: 0;
    background: rgba(1, 4, 9, 0.97);
    backdrop-filter: blur(12px);
    -webkit-backdrop-filter: blur(12px);
    border-bottom: 1px solid var(--border);
    flex-direction: column;
    align-items: center;
    padding: 12px 24px 16px;
    gap: 4px;
    z-index: 99;
  }

  .nav-links.open {
    display: flex;
  }

  .nav-links li {
    width: 100%;
    text-align: center;
  }

  .nav-links a,
  .nav-links .nav-download-btn {
    font-size: 16px;
    padding: 10px 0;
    display: block;
    width: 100%;
    text-align: center;
  }

  .nav-download {
    width: 100%;
    flex-direction: column;
    align-items: center;
  }
  .nav-download-menu {
    position: static;
    transform: none;
    padding-top: 8px;
    display: none;
    width: 100%;
    min-width: 0;
  }
  .nav-download:hover .nav-download-menu,
  .nav-download.open .nav-download-menu {
    display: block;
  }
  .nav-download-menu-inner {
    border: none;
    box-shadow: none;
    background: transparent;
    padding: 0;
  }
  .nav-download-menu a {
    justify-content: center;
    padding: 8px 12px;
  }

  .docs-sidebar {
    position: fixed;
    left: -280px;
    top: 56px;
    height: calc(100vh - 56px);
    background: var(--bg);
    z-index: 99;
    transition: left 0.25s;
    border-right: 1px solid var(--border);
  }

  .docs-sidebar.open { left: 0; }
  .docs-content { padding: 24px 16px 60px; }
}