/* ========================= */
/* Global Styles */
/* ========================= */
body {
  font-family: system-ui, -apple-system, Roboto, Arial, sans-serif;
  font-size: 16px;
  line-height: 1.55;
  color: #333;
  background-color: #fafafa;
  margin: 0;
  padding: 0;
}

a {
  text-decoration: none;
  color: #0d47a1;
}

a:hover {
  text-decoration: underline;
}

/* ========================= */
/* Navigation */
/* ========================= */
.main-nav {
  display: flex;
  justify-content: center;
  border-bottom: 1px solid #eee;
  padding: 10px 0;
  background-color: white;
  position: sticky;
  top: 0;
  z-index: 10;
}

.main-nav ul {
  list-style: none;
  display: flex;
  gap: 25px;
  margin: 0;
  padding: 0;
}

.main-nav a {
  padding: 5px 10px;
  border-radius: 5px;
  font-weight: 500;
}

.main-nav a.active {
  background-color: #e7f0ff;
  color: #0d47a1;
  font-weight: 600;
}

/* ========================= */
/* Table of Contents */
/* ========================= */
.toc {
  text-align: center;
  margin: 15px 0;
}

.toc ul {
  list-style: none;
  display: flex;
  flex-wrap: wrap;
  gap: 15px;
  justify-content: center;
  padding: 0;
  margin: 0;
}

.toc a {
  color: #0d47a1;
}

.toc a:hover {
  text-decoration: underline;
}

/* ========================= */
/* Page Header */
/* ========================= */
.page-header {
  text-align: center;
  padding: 20px 10px;
}

/* ========================= */
/* Sections */
/* ========================= */
main#content {
  max-width: 900px;
  margin: 0 auto;
  padding: 20px;
}

.explain-section {
  padding: 30px 0;
  border-bottom: 1px solid #eee;
}

.explain-section h2 {
  font-size: 1.8rem;
  color: #0d47a1;
  margin-top: 0;
}

.explain-section h3 {
  font-size: 1.3rem;
  color: #1a237e;
}

/* Smooth scrolling anchor offset */
.explain-section::before {
  content: "";
  display: block;
  height: 80px; /* match nav height */
  margin-top: -80px;
  visibility: hidden;
}

/* ========================= */
/* Notes & Code Blocks */
/* ========================= */
.note {
  background-color: #e3f2fd;
  padding: 10px 15px;
  border-left: 4px solid #0d47a1;
  margin: 15px 0;
}

.code {
  background-color: #f6f8fa;
  font-family: monospace;
  padding: 8px;
  border-radius: 4px;
  display: block;
  margin: 10px 0;
}

/* ========================= */
/* Footer */
/* ========================= */
.page-footer {
  text-align: center;
  padding: 20px;
  font-size: 0.9rem;
  color: #666;
  border-top: 1px solid #eee;
}