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

:root {
  --color-bg: #fff;
  --color-text: #1a1a1a;
  --color-muted: #555;
  --color-border: #e0e0e0;
  --color-accent: #2563eb;
  --color-accent-hover: #1d4ed8;
  --color-surface: #f8f9fa;
  --font-sans: system-ui, -apple-system, "Segoe UI", Roboto, sans-serif;
  --font-mono: ui-monospace, "Cascadia Code", "Source Code Pro", Menlo, monospace;
  --max-width: 52rem;
}

html {
  font-family: var(--font-sans);
  font-size: 16px;
  line-height: 1.6;
  color: var(--color-text);
  background: var(--color-bg);
}

header {
  border-bottom: 1px solid var(--color-border);
}

nav {
  max-width: var(--max-width);
  margin: 0 auto;
  padding: 0.75rem 1.5rem;
  display: flex;
  align-items: center;
  justify-content: space-between;
}

.nav-brand {
  font-weight: 700;
  font-size: 1.125rem;
  color: var(--color-text);
  text-decoration: none;
}

.nav-right {
  display: flex;
  align-items: center;
  gap: 0.75rem;
}

.nav-link {
  font-size: 0.875rem;
  color: var(--color-accent);
  text-decoration: none;
}

.nav-link:hover {
  text-decoration: underline;
}

main {
  max-width: var(--max-width);
  margin: 0 auto;
  padding: 2rem 1.5rem;
}

h1 {
  font-size: 1.75rem;
  font-weight: 700;
  margin-bottom: 0.25rem;
}

h2 {
  font-size: 1.375rem;
  font-weight: 600;
  margin-bottom: 0.75rem;
}

h3 {
  font-size: 1.125rem;
  font-weight: 600;
  margin-bottom: 0.5rem;
}

p {
  margin-bottom: 1rem;
}

.subtitle {
  color: var(--color-muted);
  margin-bottom: 2rem;
}

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

code {
  font-family: var(--font-mono);
  font-size: 0.875em;
  background: var(--color-surface);
  padding: 0.125rem 0.375rem;
  border-radius: 0.25rem;
}

.docs-section {
  margin-bottom: 2.5rem;
}

.steps {
  padding-left: 1.5rem;
  margin-bottom: 1rem;
}

.steps li {
  margin-bottom: 0.5rem;
}

.package-list {
  list-style: none;
  display: flex;
  flex-wrap: wrap;
  gap: 0.5rem;
  margin-bottom: 1rem;
}

.package-list li code {
  display: inline-block;
}

.topic-group {
  margin-bottom: 1.5rem;
}

.exercise-table {
  width: 100%;
  border-collapse: collapse;
  margin-bottom: 0.5rem;
  font-size: 0.9375rem;
}

.exercise-table th,
.exercise-table td {
  padding: 0.5rem 0.75rem;
  text-align: left;
  border-bottom: 1px solid var(--color-border);
}

.exercise-table th {
  font-weight: 600;
  font-size: 0.8125rem;
  text-transform: uppercase;
  letter-spacing: 0.025em;
  color: var(--color-muted);
  background: var(--color-surface);
}

.score-col {
  width: 4rem;
  text-align: center;
}

ul {
  padding-left: 1.5rem;
  margin-bottom: 1rem;
}

ol {
  padding-left: 1.5rem;
  margin-bottom: 1rem;
}