:root {
  --bg: #050816;
  --bg-alt: #0b1022;
  --accent: #4f46e5;
  --accent-soft: #1d253f;
  --text: #e5e7eb;
  --muted: #9ca3af;
  --border: #1f2937;
  --radius: 10px;
  --shadow: 0 18px 45px rgba(0, 0, 0, 0.6);
  --font-sans: system-ui, -apple-system, BlinkMacSystemFont, "Segoe UI", sans-serif;
}

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

body {
  margin: 0;
  font-family: var(--font-sans);
  background: radial-gradient(circle at top, #111827 0, var(--bg) 45%, #020617 100%);
  color: var(--text);
}

/* Layout */

.container {
  width: min(1100px, 100% - 2.5rem);
  margin: 0 auto;
}

.site-header {
  padding: 1.5rem 0 1rem;
  border-bottom: 1px solid rgba(31, 41, 55, 0.7);
  backdrop-filter: blur(12px);
  background: linear-gradient(to bottom, rgba(15, 23, 42, 0.95), transparent);
}

.site-header h1 {
  margin: 0;
  letter-spacing: 0.08em;
  text-transform: uppercase;
  font-weight: 700;
  font-size: 1.35rem;
}

.tagline,
.breadcrumb {
  margin: 0.3rem 0 0;
  color: var(--muted);
  font-size: 0.9rem;
}

.breadcrumb a {
  color: var(--muted);
  text-decoration: none;
}

.breadcrumb a:hover {
  color: var(--text);
}

/* Contents page */

.contents {
  padding: 1.75rem 0 2.5rem;
}

.contents h2 {
  margin-bottom: 1rem;
  font-size: 1.3rem;
}

.module-card {
  background: radial-gradient(circle at top left, #111827 0, #020617 52%, #000 100%);
  border-radius: var(--radius);
  padding: 1.25rem 1.4rem;
  margin-bottom: 1rem;
  border: 1px solid rgba(55, 65, 81, 0.8);
  box-shadow: var(--shadow);
}

.module-card h3 {
  margin: 0 0 0.6rem;
  font-size: 1.05rem;
  letter-spacing: 0.04em;
}

.empty {
  color: var(--muted);
  font-size: 0.85rem;
}

.topic-list {
  list-style: none;
  padding: 0;
  margin: 0.2rem 0 0;
}

.topic-list li {
  margin: 0.15rem 0;
}

.topic-list a {
  display: inline-flex;
  align-items: center;
  gap: 0.4rem;
  padding: 0.25rem 0.4rem;
  border-radius: 999px;
  text-decoration: none;
  color: var(--text);
  font-size: 0.9rem;
  background: transparent;
  transition: background 0.18s ease, transform 0.18s ease, color 0.18s ease;
}

.topic-list a::before {
  content: "\2022";
  color: var(--accent);
  font-size: 0.9rem;
}

.topic-list a:hover {
  background: var(--accent-soft);
  transform: translateY(-1px);
}

/* Note view */

.note-container {
  display: grid;
  grid-template-columns: minmax(0, 220px) minmax(0, 1fr);
  gap: 1.5rem;
  padding: 1.75rem 0 3rem;
}

.note-sidebar {
  background: linear-gradient(145deg, #020617, #020617, #111827);
  border-radius: var(--radius);
  border: 1px solid rgba(55, 65, 81, 0.9);
  box-shadow: var(--shadow);
  padding: 1rem 1.1rem;
  font-size: 0.9rem;
}

.note-sidebar h3 {
  margin-top: 0.5rem;
  margin-bottom: 0.4rem;
  font-size: 0.95rem;
  text-transform: uppercase;
  letter-spacing: 0.06em;
  color: var(--muted);
}

.note-sidebar ul {
  list-style: none;
  margin: 0.2rem 0 0;
  padding: 0;
}

.note-sidebar li {
  margin: 0.15rem 0;
}

.back-link {
  display: inline-block;
  margin-bottom: 0.6rem;
  font-size: 0.85rem;
  color: var(--muted);
  text-decoration: none;
}

.back-link:hover {
  color: var(--text);
}

.note-content {
  background: radial-gradient(circle at top left, #020617 0, #020617 45%, #020617 100%);
  border-radius: var(--radius);
  border: 1px solid rgba(55, 65, 81, 0.9);
  box-shadow: var(--shadow);
  padding: 1.4rem 1.6rem;
  overflow-x: auto;
}

/* Basic markdown styling */

.markdown-body h1,
.markdown-body h2,
.markdown-body h3,
.markdown-body h4 {
  margin-top: 1.1rem;
  margin-bottom: 0.5rem;
}

.markdown-body h1 { font-size: 1.5rem; }
.markdown-body h2 { font-size: 1.35rem; }
.markdown-body h3 { font-size: 1.15rem; }

.markdown-body p {
  line-height: 1.6;
  margin: 0.4rem 0;
}

.markdown-body a {
  color: var(--accent);
  text-decoration: none;
}

.markdown-body a:hover {
  text-decoration: underline;
}

.markdown-body code {
  font-family: ui-monospace, SFMono-Regular, Menlo, Monaco, Consolas, "Liberation Mono", "Courier New", monospace;
  font-size: 0.85em;
  background: rgba(15, 23, 42, 0.9);
  border-radius: 4px;
  padding: 0.08rem 0.25rem;
}

.markdown-body pre code {
  padding: 0;
  background: transparent;
}

.markdown-body pre {
  background: #020617;
  border-radius: 6px;
  padding: 0.75rem 0.9rem;
  overflow-x: auto;
  border: 1px solid rgba(55, 65, 81, 0.9);
}

/* Responsive */

@media (max-width: 800px) {
  .note-container {
    grid-template-columns: minmax(0, 1fr);
  }

  .note-sidebar {
    order: -1;
  }
}