:root {
  --bg: #f5f5f5;
  --surface: #ffffff;
  --surface-soft: #eaeaea;
  --text: #111111;
  --muted: #444444;
  --line: #d6d6d6;
  --button: #111111;
  --button-text: #ffffff;
  --accent: #2d6cdf;
  --accent-hover: #1f54b0;
  --nav-bg: #e7e7e7;
  --nav-hover: #d6d6d6;
  --shadow: rgba(0, 0, 0, 0.08);
}

:root[data-theme="dark"] {
  --bg: #0d1117;
  --surface: #161b22;
  --surface-soft: #21262d;
  --text: #f0f3f6;
  --muted: #b7c0cc;
  --line: #30363d;
  --button: #f0f3f6;
  --button-text: #0d1117;
  --accent: #58a6ff;
  --accent-hover: #79b8ff;
  --nav-bg: #21262d;
  --nav-hover: #30363d;
  --shadow: rgba(0, 0, 0, 0.35);
}

* { box-sizing: border-box; }

body {
  margin: 0;
  padding: 0;
  background: var(--bg);
  color: var(--text);
  font-family: Arial, sans-serif;
  line-height: 1.6;
  transition: background 0.2s ease, color 0.2s ease;
}

main {
  max-width: 1000px;
  margin: auto;
  padding: 32px 20px 48px;
}

h1, h2, h3 { line-height: 1.2; }

h1 {
  font-size: clamp(2rem, 5vw, 2.75rem);
  margin-bottom: 0.5rem;
}

h2 {
  margin-top: 3rem;
  border-bottom: 2px solid var(--line);
  padding-bottom: 0.5rem;
}

a { color: var(--accent); }

code, pre {
  background: var(--surface-soft);
  padding: 2px 6px;
  border-radius: 4px;
}

pre {
  padding: 16px;
  overflow-x: auto;
}

.topnav {
  margin-bottom: 2rem;
  display: flex;
  gap: 0.65rem;
  flex-wrap: wrap;
  align-items: center;
}

.topnav a,
.theme-toggle {
  text-decoration: none;
  color: var(--text);
  background: var(--nav-bg);
  border: 1px solid var(--line);
  padding: 8px 12px;
  border-radius: 999px;
  font-size: 0.95rem;
}

.topnav a:hover,
.theme-toggle:hover { background: var(--nav-hover); }

.topnav a[aria-current="page"] {
  background: var(--text);
  color: var(--bg);
}

.theme-toggle {
  cursor: pointer;
  margin-left: auto;
  font-family: inherit;
}

.hero {
  text-align: center;
  margin-bottom: 3rem;
  padding: 2rem;
  background: var(--surface);
  border: 1px solid var(--line);
  border-radius: 20px;
  box-shadow: 0 12px 30px var(--shadow);
}

.eyebrow {
  color: var(--muted);
  text-transform: uppercase;
  letter-spacing: 0.12em;
  font-size: 0.78rem;
  margin: 0 0 0.75rem;
}

.button-row {
  display: flex;
  justify-content: center;
  gap: 0.75rem;
  flex-wrap: wrap;
  margin-top: 1rem;
}

.repo-link,
.notebook-link {
  display: inline-block;
  padding: 12px 18px;
  color: var(--button-text);
  text-decoration: none;
  border-radius: 10px;
  transition: transform 0.2s ease, opacity 0.2s ease, background 0.2s ease;
}

.repo-link { background: var(--button); }

.notebook-link {
  background: var(--accent);
  color: #ffffff;
}

.repo-link:hover,
.notebook-link:hover {
  opacity: 0.9;
  transform: translateY(-1px);
}

.notebook-link:hover { background: var(--accent-hover); }

.figure { margin: 3rem 0; }

.figure img {
  width: 100%;
  border-radius: 14px;
  border: 1px solid var(--line);
  background: var(--surface);
  box-shadow: 0 10px 24px var(--shadow);
}

.caption {
  margin-top: 0.75rem;
  color: var(--muted);
  font-size: 0.95rem;
}

table {
  width: 100%;
  border-collapse: collapse;
  margin: 2rem 0;
  background: var(--surface);
  box-shadow: 0 8px 18px var(--shadow);
}

th, td {
  border: 1px solid var(--line);
  padding: 12px;
  text-align: left;
}

th { background: var(--surface-soft); }

footer {
  margin-top: 5rem;
  padding-top: 2rem;
  border-top: 2px solid var(--line);
  color: var(--muted);
  font-size: 0.9rem;
}

@media (max-width: 700px) {
  main { padding: 20px 14px 36px; }
  .theme-toggle { margin-left: 0; }
  .hero { padding: 1.25rem; }
}