:root {
  --bg: #f4f6ff;
  --surface: #ffffff;
  --primary: #2f5dff;
  --primary-soft: #e8eeff;
  --text: #172031;
  --muted: #5a647d;
  --border: #dfe4f5;
  --shadow: rgba(34, 64, 168, 0.12);
}

* {
  box-sizing: border-box;
}

html {
  scroll-behavior: smooth;
}

body {
  margin: 0;
  min-height: 100vh;
  font-family: Inter, system-ui, -apple-system, BlinkMacSystemFont, "Segoe UI", sans-serif;
  background: var(--bg);
  color: var(--text);
  line-height: 1.6;
}

img {
  max-width: 100%;
}

.container {
  width: min(1120px, 100% - 2rem);
  margin: 0 auto;
}

.topbar {
  background: white;
  border-bottom: 1px solid #e8ecf7;
  position: sticky;
  top: 0;
  z-index: 10;
}

.nav-container {
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 1rem;
  padding: 1rem 0;
}

.brand {
  color: var(--text);
  text-decoration: none;
  font-size: 1.1rem;
  font-weight: 700;
}

.site-nav {
  display: flex;
  flex-wrap: wrap;
  gap: 1rem;
}

.site-nav a {
  color: var(--muted);
  text-decoration: none;
  font-size: 0.95rem;
  transition: color 0.2s ease;
}

.site-nav a:hover,
.site-nav a.active {
  color: var(--primary);
}

.site-nav a.nav-cta {
  background: var(--primary);
  color: #ffffff;
  padding: 0.35rem 0.85rem;
  border-radius: 999px;
  font-weight: 600;
  font-size: 0.85rem;
  transition: background-color 0.18s ease, transform 0.18s ease;
}

.site-nav a.nav-cta:hover {
  background: #1d46e6;
  color: #ffffff;
  transform: translateY(-1px);
}

/* ---------- Progress tracker (shared across pages) ---------- */
.progress-badge {
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 0.5rem;
  background: var(--primary-soft);
  color: var(--primary);
  padding: 0.55rem 0.75rem;
  border-radius: 8px;
  font-size: 0.85rem;
  font-weight: 600;
  margin-bottom: 0.5rem;
}
.progress-badge .bar {
  flex: 1;
  height: 6px;
  background: #ffffff;
  border-radius: 999px;
  overflow: hidden;
}
.progress-badge .bar > i {
  display: block;
  height: 100%;
  width: 0%;
  background: var(--primary);
  transition: width 0.25s ease;
}
.progress-tag {
  display: inline-flex;
  align-items: center;
  gap: 0.45rem;
  padding: 0.3rem 0.7rem;
  border-radius: 999px;
  background: var(--primary-soft);
  color: var(--primary);
  font-size: 0.82rem;
  font-weight: 600;
  cursor: pointer;
  user-select: none;
  margin: 0 0 0.6rem;
  transition: background-color 0.18s ease;
}
.progress-tag input { accent-color: var(--primary); cursor: pointer; }
.progress-tag.done { background: #d6f5e1; color: #1f7a3c; }
.part-banner {
  display: inline-block;
  padding: 0.3rem 0.8rem;
  border-radius: 999px;
  background: #172031;
  color: #ffffff;
  font-size: 0.78rem;
  letter-spacing: 0.08em;
  text-transform: uppercase;
  margin-bottom: 0.6rem;
}
.part-banner.b { background: var(--primary); }

.home-hero {
  background: linear-gradient(135deg, #4f61ff 0%, #75b6ff 100%);
  color: white;
  padding: 4rem 0 3rem;
}

.hero-inner {
  display: grid;
  grid-template-columns: 1.5fr 1fr;
  gap: 2rem;
  align-items: center;
}

.eyebrow {
  display: inline-block;
  text-transform: uppercase;
  letter-spacing: 0.15em;
  font-size: 0.8rem;
  margin-bottom: 1rem;
  color: rgba(255, 255, 255, 0.85);
}

.home-hero h1 {
  margin-top: 0;
  font-size: clamp(2.5rem, 4vw, 3.75rem);
  line-height: 1.05;
}

.home-hero p {
  max-width: 720px;
  margin: 1.5rem 0 2rem;
  font-size: 1.05rem;
  color: rgba(255, 255, 255, 0.92);
}

.button-row {
  display: flex;
  gap: 1rem;
  flex-wrap: wrap;
}

.primary-btn,
.link-btn,
.secondary-btn {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  padding: 0.95rem 1.6rem;
  border-radius: 999px;
  text-decoration: none;
  font-weight: 700;
}

.primary-btn {
  background: white;
  color: #243063;
}

.secondary-btn {
  background: rgba(255, 255, 255, 0.18);
  color: white;
  border: 1px solid rgba(255, 255, 255, 0.32);
}

.section {
  padding: 2.4rem 0;
  scroll-margin-top: 6rem;
}

.section h2 {
  margin-bottom: 1.25rem;
  font-size: clamp(2rem, 3vw, 2.5rem);
}

.section h3 {
  margin: 1.4rem 0 0.7rem;
}

.cards-grid,
.grid,
.resource-cards {
  display: grid;
  gap: 1.5rem;
  grid-template-columns: repeat(auto-fit, minmax(240px, 1fr));
}

article {
  background: var(--surface);
  border: 1px solid var(--border);
  border-radius: 1.25rem;
  padding: 1.75rem;
  box-shadow: 0 18px 40px var(--shadow);
}

article h3,
article h4 {
  margin-top: 0;
}

.article-meta,
.guide-summary ul,
.text-grid ul {
  margin: 0;
  padding-left: 1.25rem;
}

.link-btn {
  margin-top: 1rem;
  background: var(--primary);
  color: white;
}

.page-header {
  padding: 3rem 0 2rem;
}

.page-header h1 {
  margin: 0 0 0.75rem;
  font-size: clamp(2.5rem, 4vw, 3.5rem);
}

.text-grid {
  display: grid;
  gap: 1.75rem;
  grid-template-columns: repeat(auto-fit, minmax(300px, 1fr));
}

footer.site-footer {
  background: white;
  padding: 2rem 0;
  border-top: 1px solid #e8ecf7;
}

.code-block {
  display: block;
  background: #0d1117;
  color: #f8fafc;
  border: 1px solid #273244;
  border-radius: 10px;
  padding: 1rem 1.15rem;
  overflow-x: auto;
  font-family: ui-monospace, SFMono-Regular, Menlo, Monaco, Consolas, "Liberation Mono", "Courier New", monospace;
  margin: 1rem 0;
  box-shadow: inset 0 1px 0 rgba(255, 255, 255, 0.05);
}

.code-block pre {
  margin: 0;
  font-size: 0.93rem;
  line-height: 1.6;
  white-space: pre-wrap;
  word-break: break-word;
}

.page-grid {
  display: grid;
  grid-template-columns: 280px minmax(0, 1fr);
  gap: 2rem;
}

.page-sidebar {
  position: sticky;
  top: 5rem;
  align-self: start;
  display: flex;
  flex-direction: column;
  gap: 0.35rem;
  padding: 1rem;
  background: rgba(255, 255, 255, 0.72);
  border: 1px solid var(--border);
  border-radius: 10px;
  backdrop-filter: blur(10px);
  max-height: calc(100vh - 6.5rem);
  overflow-y: auto;
  scrollbar-width: thin;
}

.page-sidebar h3 {
  margin: 0 0 0.35rem;
  font-size: 1rem;
  text-transform: uppercase;
  letter-spacing: 0.12em;
  color: var(--primary);
}

.sidebar-link {
  display: block;
  color: var(--muted);
  text-decoration: none;
  padding: 0.55rem 0.75rem;
  border-radius: 8px;
  transition: background-color 0.2s ease, color 0.2s ease;
}

.sidebar-link:hover,
.sidebar-link:focus,
.sidebar-link.active {
  color: var(--primary);
  background: var(--primary-soft);
}

.practice-group {
  border-top: 1px solid var(--border);
  padding-top: 1.5rem;
  margin-top: 1.5rem;
}

.practice-heading {
  display: flex;
  flex-wrap: wrap;
  align-items: center;
  gap: 0.9rem;
  margin-bottom: 0.6rem;
}

.practice-heading h2 {
  margin: 0;
}

.practice-open-btn {
  display: inline-flex;
  align-items: center;
  gap: 0.45rem;
  padding: 0.45rem 0.95rem;
  border-radius: 999px;
  background: var(--primary);
  color: #ffffff;
  text-decoration: none;
  font-size: 0.85rem;
  font-weight: 600;
  letter-spacing: 0.01em;
  box-shadow: 0 6px 18px rgba(47, 93, 255, 0.28);
  transition: transform 0.18s ease, box-shadow 0.18s ease, background-color 0.18s ease;
}

.practice-open-btn:hover,
.practice-open-btn:focus-visible {
  background: #1d46e6;
  transform: translateY(-1px);
  box-shadow: 0 10px 22px rgba(47, 93, 255, 0.36);
  outline: none;
}

.practice-open-btn::after {
  content: "↗";
  font-size: 0.95rem;
  line-height: 1;
}

.note-card {
  background: var(--surface);
  border: 1px solid var(--border);
  border-radius: 10px;
  padding: 1rem 1.15rem;
  margin: 1rem 0;
}

.page-sidebar::-webkit-scrollbar {
  width: 8px;
}

.page-sidebar::-webkit-scrollbar-thumb {
  background: #cdd6ef;
  border-radius: 999px;
}

@media (max-width: 980px) {
  .page-grid {
    grid-template-columns: 1fr;
  }

  .page-sidebar {
    position: static;
  }
}

@media (max-width: 850px) {
  .hero-inner,
  .text-grid {
    grid-template-columns: 1fr;
  }

  .site-nav {
    justify-content: center;
  }
}