* {
  box-sizing: border-box;
}

html {
  scroll-behavior: smooth;
}

body {
  margin: 0;
  font-family: "Segoe UI", Arial, sans-serif;
  line-height: 1.7;
  color: #2b2b3a;
  background: #f4f6fb;
}

/* ---------- Navbar ---------- */
#navbar {
  position: fixed;
  top: 0;
  left: 0;
  width: 250px;
  height: 100vh;
  overflow-y: auto;
  background: #2f3b6e;
  color: #ffffff;
  padding: 24px 0;
}

#navbar header {
  font-size: 1.3rem;
  font-weight: bold;
  padding: 0 24px 16px;
  border-bottom: 1px solid rgba(255, 255, 255, 0.25);
}

#navbar ul {
  list-style: none;
  margin: 0;
  padding: 12px 0;
}

.nav-link {
  display: block;
  padding: 10px 24px;
  color: #dfe5ff;
  text-decoration: none;
  border-left: 4px solid transparent;
}

.nav-link:hover,
.nav-link:focus {
  background: rgba(255, 255, 255, 0.12);
  border-left-color: #ffc94d;
  color: #ffffff;
}

/* ---------- Main content ---------- */
#main-doc {
  margin-left: 250px;
  padding: 40px 48px 60px;
  max-width: 900px;
}

.page-title {
  margin-bottom: 32px;
  padding-bottom: 16px;
  border-bottom: 4px solid #ffc94d;
}

.page-title h1 {
  margin: 0;
  font-size: 2.2rem;
  color: #2f3b6e;
}

.subtitle {
  margin: 6px 0 0;
  color: #5b6180;
  font-style: italic;
}

.main-section {
  background: #ffffff;
  padding: 24px 28px;
  margin-bottom: 28px;
  border-radius: 10px;
  box-shadow: 0 2px 8px rgba(0, 0, 0, 0.08);
  scroll-margin-top: 20px;
}

.main-section header h2 {
  margin: 0 0 12px;
  font-size: 1.6rem;
  color: #2f3b6e;
}

.main-section h3 {
  margin: 20px 0 6px;
  color: #3d4a8a;
  font-size: 1.15rem;
}

p {
  margin: 0 0 14px;
}

ul, ol {
  margin: 0 0 14px;
  padding-left: 26px;
}

li {
  margin-bottom: 6px;
}

code {
  background: #eef1ff;
  color: #b5303f;
  padding: 2px 6px;
  border-radius: 4px;
  font-family: Consolas, "Courier New", monospace;
  font-size: 0.95em;
}

/* ---------- Helpful boxes ---------- */
.tip {
  background: #fff7de;
  border-left: 5px solid #ffc94d;
  padding: 12px 16px;
  border-radius: 6px;
  margin-top: 12px;
}

.example {
  background: #e9f6ee;
  border-left: 5px solid #3fa66b;
  padding: 12px 16px 2px;
  border-radius: 6px;
}

/* ---------- Mobile ---------- */
@media (max-width: 800px) {
  #navbar {
    position: static;
    width: 100%;
    height: auto;
  }

  #main-doc {
    margin-left: 0;
    padding: 24px 16px 40px;
  }
}