:root {
  --bg: #ffffff;
  --bg-soft: #f8fafc;
  --surface: #f1f5f9;
  --line: #e2e8f0;
  --ink: #0f172a;
  --muted: #64748b;
  --accent: #2563eb;
  --accent-hover: #1d4ed8;
  --green: #16a34a;
  --green-bg: #f0fdf4;
  --green-border: #bbf7d0;
  --yellow-bg: #fefce8;
  --yellow-border: #fde68a;
  --red-bg: #fef2f2;
  --red-border: #fecaca;
  --code-bg: #f8fafc;
  --radius: 8px;
}

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

html {
  scroll-behavior: smooth;
}

body {
  font-family: "Inter", -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, sans-serif;
  color: var(--ink);
  background: var(--bg);
  line-height: 1.6;
  -webkit-font-smoothing: antialiased;
}

a {
  color: var(--accent);
  text-decoration: none;
  transition: color 150ms ease;
}

a:hover {
  color: var(--accent-hover);
  text-decoration: underline;
}

code {
  background: var(--code-bg);
  border: 1px solid var(--line);
  border-radius: 4px;
  padding: 0.15em 0.35em;
  font-size: 0.88em;
  font-family: "JetBrains Mono", "Fira Code", monospace;
  color: #be185d;
}

pre {
  background: var(--bg-soft);
  border: 1px solid var(--line);
  border-radius: var(--radius);
  padding: 1rem 1.2rem;
  overflow-x: auto;
  font-size: 0.85rem;
  line-height: 1.65;
  margin: 0.75rem 0;
}

pre code {
  background: none;
  border: none;
  padding: 0;
  color: var(--ink);
  font-size: inherit;
}

h1, h2, h3, h4 {
  font-weight: 600;
  line-height: 1.25;
  color: var(--ink);
}

h1 {
  font-size: 2rem;
}

h2 {
  font-size: 1.5rem;
  margin-top: 2.5rem;
  margin-bottom: 0.75rem;
}

h3 {
  font-size: 1.15rem;
  margin-top: 1.5rem;
  margin-bottom: 0.5rem;
}

p {
  margin-bottom: 0.75rem;
  max-width: 65ch;
}

ul {
  padding-left: 1.5rem;
  margin-bottom: 0.75rem;
}

li {
  margin-bottom: 0.3rem;
}

/* Header */
.site-header {
  position: sticky;
  top: 0;
  z-index: 10;
  display: flex;
  align-items: center;
  justify-content: space-between;
  padding: 0.75rem 2rem;
  background: rgba(255, 255, 255, 0.9);
  backdrop-filter: blur(8px);
  border-bottom: 1px solid var(--line);
}

.header-brand {
  display: flex;
  align-items: center;
  gap: 0.6rem;
  text-decoration: none;
  color: var(--ink);
  font-weight: 700;
  font-size: 1rem;
}

.header-brand svg {
  width: 28px;
  height: 28px;
  flex-shrink: 0;
}

.header-nav {
  display: flex;
  align-items: center;
  gap: 1.5rem;
}

.header-nav a {
  color: var(--muted);
  font-size: 0.88rem;
  font-weight: 500;
  text-decoration: none;
  transition: color 150ms ease;
}

.header-nav a:hover {
  color: var(--ink);
  text-decoration: none;
}

.header-nav a.active {
  color: var(--ink);
  font-weight: 600;
}

/* Hero */
.hero {
  text-align: center;
  padding: 5rem 2rem 4rem;
  max-width: 720px;
  margin: 0 auto;
}

.hero h1 {
  font-size: 2.75rem;
  font-weight: 700;
  margin-bottom: 1rem;
  letter-spacing: -0.02em;
}

.hero .lead {
  font-size: 1.1rem;
  color: var(--muted);
  margin-bottom: 2rem;
  max-width: 540px;
  margin-left: auto;
  margin-right: auto;
}

.hero-actions {
  display: flex;
  justify-content: center;
  gap: 0.75rem;
  flex-wrap: wrap;
}

.btn {
  display: inline-flex;
  align-items: center;
  gap: 0.4rem;
  padding: 0.6rem 1.2rem;
  border-radius: var(--radius);
  font-size: 0.9rem;
  font-weight: 600;
  text-decoration: none;
  transition: background 150ms ease, color 150ms ease;
  cursor: pointer;
}

.btn-primary {
  background: var(--ink);
  color: #fff;
  border: 1px solid var(--ink);
}

.btn-primary:hover {
  background: #1e293b;
  color: #fff;
  text-decoration: none;
}

.btn-outline {
  background: transparent;
  color: var(--ink);
  border: 1px solid var(--line);
}

.btn-outline:hover {
  background: var(--bg-soft);
  color: var(--ink);
  text-decoration: none;
}

/* Main content */
main {
  max-width: 780px;
  margin: 0 auto;
  padding: 0 2rem 4rem;
}

/* Section */
.section {
  margin-bottom: 3rem;
}

.section h2 {
  margin-top: 0;
  padding-bottom: 0.5rem;
  border-bottom: 1px solid var(--line);
}

/* Cards */
.card-grid {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: 1rem;
}

.card {
  padding: 1.25rem;
  border: 1px solid var(--line);
  border-radius: var(--radius);
  background: var(--bg);
  transition: border-color 200ms ease;
}

.card:hover {
  border-color: #94a3b8;
}

.card h3 {
  margin: 0 0 0.4rem;
  font-size: 1rem;
}

.card p {
  margin: 0;
  color: var(--muted);
  font-size: 0.9rem;
}

/* Callout */
.callout {
  border-radius: var(--radius);
  padding: 0.8rem 1rem;
  margin: 1rem 0;
  font-size: 0.9rem;
  display: flex;
  gap: 0.6rem;
  align-items: flex-start;
  line-height: 1.5;
}

.callout-info {
  background: #eff6ff;
  border: 1px solid #bfdbfe;
  color: #1e40af;
}

.callout-warn {
  background: var(--yellow-bg);
  border: 1px solid var(--yellow-border);
  color: #92400e;
}

.callout-icon {
  flex-shrink: 0;
  margin-top: 0.1rem;
}

/* Table */
.table-wrap {
  overflow-x: auto;
  margin: 1rem 0;
}

table {
  width: 100%;
  border-collapse: collapse;
  font-size: 0.9rem;
}

th, td {
  text-align: left;
  padding: 0.6rem 0.8rem;
  border-bottom: 1px solid var(--line);
}

th {
  font-weight: 600;
  font-size: 0.82rem;
  text-transform: uppercase;
  letter-spacing: 0.04em;
  color: var(--muted);
  background: var(--bg-soft);
}

tr:last-child td {
  border-bottom: none;
}

/* Badges */
.badge {
  display: inline-block;
  padding: 0.2rem 0.55rem;
  border-radius: 4px;
  font-size: 0.75rem;
  font-weight: 600;
  line-height: 1.4;
}

.badge-done {
  background: var(--green-bg);
  border: 1px solid var(--green-border);
  color: var(--green);
}

.badge-wip {
  background: #eff6ff;
  border: 1px solid #bfdbfe;
  color: #2563eb;
}

.badge-exp {
  background: var(--yellow-bg);
  border: 1px solid var(--yellow-border);
  color: #a16207;
}

/* Footer */
footer {
  border-top: 1px solid var(--line);
  padding: 1.5rem 2rem;
  text-align: center;
  color: var(--muted);
  font-size: 0.85rem;
}

footer a {
  color: var(--muted);
  font-weight: 500;
}

footer a:hover {
  color: var(--ink);
}

/* Responsive */
@media (max-width: 640px) {
  .site-header {
    padding: 0.75rem 1rem;
  }

  .header-nav {
    gap: 1rem;
  }

  .header-nav a {
    font-size: 0.82rem;
  }

  .hero {
    padding: 3rem 1rem 2.5rem;
  }

  .hero h1 {
    font-size: 2rem;
  }

  main {
    padding: 0 1rem 3rem;
  }

  .card-grid {
    grid-template-columns: 1fr;
  }

  .hero-actions {
    flex-direction: column;
    align-items: stretch;
  }

  .btn {
    justify-content: center;
  }
}