:root {
  --bg: #ffffff;
  --text: #1a1a1a;
  --muted: #666666;
  --accent: #004de6;
  --border: #e5e7eb;
  --max-width: 1200px;
}

* {
  box-sizing: border-box;
}

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

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

.site-header {
  border-bottom: 1px solid var(--border);
  display: flex;
  justify-content: space-between;
  align-items: center;
  padding: 0.8rem 1rem;
}

.brand-wordmark {
  height: 24px;
}

.top-nav {
  display: flex;
  gap: 1rem;
}

.layout {
  max-width: var(--max-width);
  margin: 0 auto;
  display: grid;
  grid-template-columns: 260px 1fr;
  gap: 2rem;
  padding: 1rem;
}

.sidebar {
  border-right: 1px solid var(--border);
  padding-right: 1rem;
}

.sidebar ul {
  list-style: none;
  margin: 0;
  padding: 0;
}

.sidebar li {
  margin: 0.3rem 0;
}

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

.prev-next {
  margin-top: 2rem;
  padding-top: 1rem;
  border-top: 1px solid var(--border);
  display: flex;
  justify-content: space-between;
  gap: 1rem;
}

.site-footer {
  border-top: 1px solid var(--border);
  padding: 1rem;
  color: var(--muted);
  font-size: 0.95rem;
}

body[data-path="index"] .sidebar a[href="/index.html"],
body[data-path="concept"] .sidebar a[href="/concept.html"],
body[data-path="build-it/index"] .sidebar a[href="/build-it/index.html"],
body[data-path="build-it/bom"] .sidebar a[href="/build-it/bom.html"],
body[data-path="play-it/index"] .sidebar a[href="/play-it/index.html"],
body[data-path="teach-with-it/index"] .sidebar a[href="/teach-with-it/index.html"],
body[data-path="downloads"] .sidebar a[href="/downloads.html"],
body[data-path="contribute"] .sidebar a[href="/contribute.html"],
body[data-path="contributors"] .sidebar a[href="/contributors.html"] {
  font-weight: bold;
  text-decoration: underline;
}

@media (max-width: 900px) {
  .layout {
    grid-template-columns: 1fr;
  }

  .sidebar {
    border-right: 0;
    border-bottom: 1px solid var(--border);
    padding-bottom: 1rem;
  }
}

@media print {
  .site-header,
  .sidebar,
  .prev-next,
  .site-footer {
    display: none;
  }

  .layout {
    display: block;
    padding: 0;
  }
}