:root {
  --bg: #fdfdfd;
  --card: #ffffff;
  --ink: #222;
  --rule: #e0e0e0;
  --accent: #1e88e5;
  --accent-bg: #eef8ff;
}

body {
  font-family: system-ui, -apple-system, Segoe UI, Roboto, Helvetica, Arial;
  margin: 0;
  background: var(--bg);
  color: var(--ink);
  line-height: 1.65;
}

header {
  background: var(--card);
  border-bottom: 1px solid var(--rule);
  padding: 1rem 1.5rem;
  display: flex;
  align-items: center;
  justify-content: space-between;
}

.brand {
  display: flex;
  align-items: center;
  gap: 0.75rem;
  font-weight: 700;
  font-size: 1.2rem;
}

.brand__logo {
  width: 36px;
  height: 36px;
  border-radius: 8px;
  background: linear-gradient(135deg, var(--accent), #7fc4ff);
}

nav a {
  text-decoration: none;
  color: var(--accent);
  font-weight: 500;
  margin-left: 1rem;
}

main {
  max-width: 860px;
  margin: 2rem auto;
  padding: 0 1rem;
}

h1 {
  font-size: 2rem;
  margin-bottom: 1rem;
}

h2 {
  font-size: 1.3rem;
  margin-top: 1.5rem;
  color: #333;
}

p {
  margin: 0.6rem 0 1rem;
}

ul {
  margin: 0.5rem 0 1rem 1.25rem;
  padding: 0;
}

li {
  margin-bottom: 0.6rem;
}

.article-list {
  list-style: none;
  padding: 0;
}

.article-list li {
  background: var(--card);
  border: 1px solid var(--rule);
  border-radius: 10px;
  padding: 1rem;
  margin-bottom: 1rem;
  transition: box-shadow 0.2s;
}

.article-list li:hover {
  box-shadow: 0 2px 8px rgba(0,0,0,.08);
}

.article-list a {
  color: var(--accent);
  text-decoration: none;
  font-weight: 600;
}

.highlight {
  background: var(--accent-bg);
  border-left: 4px solid var(--accent);
  padding: 1rem;
  border-radius: 8px;
  font-weight: 600;
}

footer {
  border-top: 1px solid var(--rule);
  text-align: center;
  padding: 1rem;
  color: #777;
  margin-top: 3rem;
  font-size: 0.9rem;
}
.sample-toc {
  background: var(--card);
  border: 1px solid var(--rule);
  border-radius: 12px;
  padding: 1rem 1.25rem;
  margin: 1.5rem 0 2rem;
}

.sample-toc h3 {
  margin-top: 0;
  font-size: 1.1rem;
  color: var(--accent);
}

.sample-toc ol {
  margin: .5rem 0 0;
  padding-left: 1.25rem;
}

.sample-toc li {
  margin: .4rem 0;
}

.sample-toc a {
  text-decoration: none;
  color: var(--ink);
}

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