:root {
  --pb-bg: #060b16;
  --pb-bg2: #0a1124;
  --pb-panel: #0f1733;
  --pb-panel-soft: #0c132b;
  --pb-text: #eef3ff;
  --pb-muted: #9fb0e3;
  --pb-line: rgba(120, 140, 255, 0.15);
  --pb-accent: #7ee0ff;
  --pb-accent2: #8a6cff;
  --pb-accent3: #36ffc9;
  --pb-radius: 20px;
  --pb-max: 1260px;
  --pb-glow: 0 0 30px rgba(126, 224, 255, 0.35);
}

* { box-sizing: border-box; }
html { scroll-behavior: smooth; }

body {
  margin: 0;
  font-family: Outfit, Inter, system-ui, sans-serif;
  color: var(--pb-text);
  line-height: 1.7;
  background:
    radial-gradient(circle at 20% 10%, rgba(126, 224, 255, 0.12), transparent 40%),
    radial-gradient(circle at 80% 0%, rgba(138, 108, 255, 0.18), transparent 40%),
    linear-gradient(180deg, var(--pb-bg) 0%, #02050d 100%);
}

body::before {
  content: "";
  position: fixed;
  inset: 0;
  background:
    linear-gradient(rgba(255, 255, 255, 0.03) 1px, transparent 1px),
    linear-gradient(90deg, rgba(255, 255, 255, 0.03) 1px, transparent 1px);
  background-size: 60px 60px;
  pointer-events: none;
  opacity: 0.35;
}

a { color: inherit; text-decoration: none; }

.layout {
  display: grid;
  grid-template-columns: 300px minmax(0, 1fr);
  min-height: 100vh;
}

.sidebar {
  position: sticky;
  top: 0;
  height: 100vh;
  padding: 28px 20px;
  border-right: 1px solid var(--pb-line);
  background: rgba(5, 8, 20, 0.85);
  backdrop-filter: blur(14px);
  overflow: auto;
}

.brand {
  padding: 18px;
  border: 1px solid var(--pb-line);
  border-radius: 18px;
  background: linear-gradient(145deg, rgba(255, 255, 255, 0.04), rgba(255, 255, 255, 0.01));
  box-shadow: 0 20px 60px rgba(0, 0, 0, 0.5);
  margin-bottom: 20px;
}

.brand h1 { margin: 0; font-size: 1.2rem; }
.brand p { margin: 10px 0 0; color: var(--pb-muted); font-size: 0.92rem; }

.back-link {
  display: inline-flex;
  align-items: center;
  gap: 0.5rem;
  margin-bottom: 16px;
  color: var(--pb-accent);
  font-size: 0.9rem;
  font-weight: 600;
}
.back-link:hover { text-decoration: underline; }

.lang-switch {
  display: inline-flex;
  padding: 0.25rem;
  border-radius: 999px;
  background: rgba(255, 255, 255, 0.06);
  border: 1px solid var(--pb-line);
  gap: 0.15rem;
  margin-bottom: 16px;
}

.lang-option {
  padding: 0.4rem 0.85rem;
  border: none;
  border-radius: 999px;
  background: transparent;
  color: var(--pb-muted);
  font-size: 0.8rem;
  font-weight: 600;
  cursor: pointer;
  transition: color 0.18s ease, background 0.18s ease;
}

.lang-option:hover { color: var(--pb-text); }

.lang-option.is-active {
  background: rgba(126, 224, 255, 0.18);
  color: var(--pb-accent);
}

.nav { display: grid; gap: 6px; margin-top: 10px; }

.nav a {
  padding: 10px 12px;
  border-radius: 12px;
  color: var(--pb-muted);
  border: 1px solid transparent;
  transition: 0.2s ease;
  font-size: 0.94rem;
}

.nav a:hover {
  color: white;
  border-color: var(--pb-line);
  background: rgba(126, 224, 255, 0.08);
  box-shadow: 0 0 18px rgba(126, 224, 255, 0.15);
}

.sidebar-footer {
  margin-top: 22px;
  padding: 14px;
  border-radius: 16px;
  background: rgba(255, 255, 255, 0.03);
  border: 1px solid var(--pb-line);
  color: var(--pb-muted);
  font-size: 0.9rem;
}

.content { min-width: 0; padding: 36px; }
.container { width: 100%; max-width: var(--pb-max); margin: 0 auto; }

.hero {
  position: relative;
  overflow: hidden;
  border-radius: 28px;
  padding: 48px;
  border: 1px solid var(--pb-line);
  background:
    linear-gradient(145deg, rgba(126, 224, 255, 0.12), rgba(138, 108, 255, 0.12)),
    rgba(255, 255, 255, 0.03);
  box-shadow: 0 30px 80px rgba(0, 0, 0, 0.6);
  margin-bottom: 32px;
}

.hero::before {
  content: "";
  position: absolute;
  width: 420px;
  height: 420px;
  border-radius: 50%;
  background: radial-gradient(circle, rgba(126, 224, 255, 0.25), transparent 70%);
  right: -120px;
  top: -120px;
  filter: blur(10px);
}

.eyebrow {
  font-size: 0.8rem;
  letter-spacing: 0.12em;
  text-transform: uppercase;
  font-weight: 700;
  color: var(--pb-accent);
  margin-bottom: 10px;
}

.hero h2 {
  margin: 0;
  font-size: clamp(2.2rem, 4vw, 3.4rem);
  line-height: 1.05;
  max-width: 920px;
}

.hero p {
  max-width: 880px;
  color: var(--pb-muted);
  margin: 18px 0 0;
}

.hero-grid {
  display: grid;
  grid-template-columns: repeat(4, minmax(0, 1fr));
  gap: 14px;
  margin-top: 32px;
}

.metric-card {
  background: rgba(255, 255, 255, 0.04);
  border: 1px solid var(--pb-line);
  border-radius: 16px;
  padding: 16px;
  transition: 0.25s;
}

.metric-card:hover {
  transform: translateY(-3px);
  box-shadow: var(--pb-glow);
}

.metric-card .label { color: var(--pb-muted); font-size: 0.8rem; margin-bottom: 6px; }
.metric-card .value { font-size: 1.4rem; font-weight: 800; }

.section {
  margin: 34px 0;
  border-radius: 26px;
  padding: 34px;
  border: 1px solid var(--pb-line);
  background: linear-gradient(160deg, rgba(255, 255, 255, 0.035), rgba(255, 255, 255, 0.01));
  box-shadow: 0 25px 70px rgba(0, 0, 0, 0.55);
}

.section h3 { margin: 0 0 14px; font-size: 1.7rem; }
.section p { margin: 0 0 14px; color: var(--pb-muted); }
.lead { font-size: 1.05rem; margin-bottom: 18px; }

.kicker {
  margin-bottom: 14px;
  font-size: 0.78rem;
  letter-spacing: 0.1em;
  text-transform: uppercase;
  font-weight: 700;
  color: var(--pb-accent);
}

.story-block {
  border-left: 3px solid var(--pb-accent);
  padding-left: 18px;
  margin: 22px 0;
}

.quote-panel {
  margin: 24px 0;
  padding: 24px;
  border-radius: 16px;
  background: rgba(126, 224, 255, 0.06);
  border: 1px solid rgba(126, 224, 255, 0.2);
  font-style: italic;
  color: var(--pb-muted);
}

.grid-2, .grid-3, .grid-4 { display: grid; gap: 18px; }
.grid-2 { grid-template-columns: repeat(2, minmax(0, 1fr)); }
.grid-3 { grid-template-columns: repeat(3, minmax(0, 1fr)); }
.grid-4 { grid-template-columns: repeat(4, minmax(0, 1fr)); }

.card {
  border-radius: 18px;
  padding: 22px;
  border: 1px solid var(--pb-line);
  background: linear-gradient(180deg, rgba(255, 255, 255, 0.04), rgba(255, 255, 255, 0.02));
  transition: 0.25s;
}

.card:hover {
  transform: translateY(-4px);
  box-shadow: 0 0 28px rgba(126, 224, 255, 0.18);
}

.card h4 { margin: 0 0 10px; }
.card p, .card li { color: var(--pb-muted); font-size: 0.95rem; }

ul.clean { margin: 10px 0 0 18px; padding: 0; }

.pill-row { display: flex; flex-wrap: wrap; gap: 10px; margin-top: 14px; }

.pill {
  padding: 8px 12px;
  border-radius: 999px;
  background: rgba(126, 224, 255, 0.1);
  border: 1px solid rgba(126, 224, 255, 0.25);
  font-size: 0.85rem;
}

.chart {
  border-radius: 18px;
  padding: 22px;
  background: rgba(255, 255, 255, 0.03);
  border: 1px solid var(--pb-line);
  margin-top: 18px;
}

.chart-title { margin-bottom: 12px; font-weight: 600; font-size: 1rem; }
.chart svg { width: 100%; height: 220px; }

.bar { fill: var(--pb-accent); filter: drop-shadow(0 0 6px rgba(126, 224, 255, 0.6)); }
.bar.secondary { fill: var(--pb-accent2); }

.data-block {
  margin-top: 18px;
  padding: 18px;
  border-radius: 16px;
  background: rgba(255, 255, 255, 0.03);
  border: 1px solid var(--pb-line);
}

.chapter-list { display: grid; gap: 14px; }

.chapter-item {
  padding: 16px;
  border-radius: 14px;
  border: 1px solid var(--pb-line);
  background: rgba(255, 255, 255, 0.02);
  color: var(--pb-muted);
  font-size: 0.95rem;
}

.chapter-item strong { display: block; margin-bottom: 6px; color: var(--pb-text); }

.step-sequence { display: grid; gap: 18px; }

.step-card {
  display: grid;
  grid-template-columns: auto 1fr;
  gap: 20px;
  padding: 22px;
  border-radius: 18px;
  border: 1px solid var(--pb-line);
  background: linear-gradient(180deg, rgba(255, 255, 255, 0.04), rgba(255, 255, 255, 0.02));
  transition: 0.25s;
}

.step-card:hover { box-shadow: 0 0 24px rgba(126, 224, 255, 0.12); }

.step-number {
  width: 48px;
  height: 48px;
  display: grid;
  place-items: center;
  border-radius: 100%;
  background: rgba(126, 224, 255, 0.15);
  color: var(--pb-accent);
  font-weight: 800;
  font-size: 1.2rem;
}

.timeline { display: grid; gap: 20px; }

.timeline-item {
  display: grid;
  grid-template-columns: 120px 1fr;
  gap: 24px;
  align-items: start;
}

.time {
  font-weight: 700;
  color: var(--pb-accent);
  font-size: 0.95rem;
}

.phase h4 { margin: 0 0 10px; }
.phase p { margin: 0; }

.org-diagram { margin: 24px 0; }

.org-row {
  display: grid;
  grid-template-columns: repeat(4, minmax(0, 1fr));
  gap: 14px;
  margin-bottom: 10px;
}

.org-row:first-child { grid-template-columns: 1fr; }

.org-box {
  padding: 16px;
  border-radius: 14px;
  border: 1px solid var(--pb-line);
  background: rgba(255, 255, 255, 0.03);
  font-size: 0.92rem;
  color: var(--pb-muted);
}

.org-box strong { display: block; margin-bottom: 6px; color: var(--pb-text); }

.org-arrow {
  text-align: center;
  color: var(--pb-accent);
  font-size: 1.5rem;
  margin: 8px 0;
}

.table-wrap {
  overflow-x: auto;
  margin: 20px 0;
  border-radius: 16px;
  border: 1px solid var(--pb-line);
}

table {
  width: 100%;
  border-collapse: collapse;
  font-size: 0.95rem;
}

th, td {
  padding: 14px 18px;
  text-align: left;
  border-bottom: 1px solid var(--pb-line);
}

th {
  background: rgba(255, 255, 255, 0.04);
  color: var(--pb-accent);
  font-weight: 600;
}

td { color: var(--pb-muted); }
tr:last-child td { border-bottom: none; }

.badge {
  display: inline-block;
  padding: 6px 12px;
  border-radius: 999px;
  font-size: 0.8rem;
  font-weight: 700;
  margin-bottom: 12px;
}

.badge.success { background: rgba(54, 255, 201, 0.15); color: var(--pb-accent3); }
.badge.warning { background: rgba(255, 193, 7, 0.15); color: #ffc107; }
.badge.danger { background: rgba(255, 100, 100, 0.15); color: #ff6464; }

/* Quiz */
[hidden] { display: none !important; }
.quiz-section .quiz-start { margin-top: 20px; }
.quiz-section .quiz-container,
.quiz-section .quiz-results { margin-top: 24px; }

.quiz-btn {
  padding: 14px 28px;
  border-radius: 14px;
  border: 1px solid var(--pb-line);
  background: linear-gradient(145deg, rgba(126, 224, 255, 0.15), rgba(138, 108, 255, 0.12));
  color: var(--pb-text);
  font-family: inherit;
  font-size: 1rem;
  font-weight: 600;
  cursor: pointer;
  transition: 0.2s ease;
}
.quiz-btn:hover {
  background: linear-gradient(145deg, rgba(126, 224, 255, 0.25), rgba(138, 108, 255, 0.2));
  box-shadow: var(--pb-glow);
}
.quiz-btn:disabled { opacity: 0.5; cursor: not-allowed; }

.quiz-progress { margin-bottom: 24px; }
.quiz-progress-text {
  display: block;
  font-size: 0.9rem;
  color: var(--pb-muted);
  margin-bottom: 8px;
}
.quiz-progress-bar {
  height: 6px;
  border-radius: 999px;
  background: rgba(255, 255, 255, 0.08);
  overflow: hidden;
}
.quiz-progress-fill {
  height: 100%;
  background: linear-gradient(90deg, var(--pb-accent), var(--pb-accent2));
  border-radius: 999px;
  transition: width 0.3s ease;
}

.quiz-question {
  font-size: 1.2rem;
  font-weight: 600;
  margin-bottom: 20px;
  color: var(--pb-text);
}

.quiz-options {
  display: grid;
  gap: 12px;
  margin-bottom: 20px;
}
.quiz-option {
  padding: 16px 20px;
  border-radius: 14px;
  border: 1px solid var(--pb-line);
  background: rgba(255, 255, 255, 0.03);
  color: var(--pb-muted);
  font-size: 1rem;
  text-align: left;
  cursor: pointer;
  transition: 0.2s ease;
}
.quiz-option:hover:not(.disabled) {
  border-color: rgba(126, 224, 255, 0.4);
  background: rgba(126, 224, 255, 0.08);
  color: var(--pb-text);
}
.quiz-option.selected {
  border-color: var(--pb-accent);
  background: rgba(126, 224, 255, 0.12);
  color: var(--pb-text);
}
.quiz-option.correct {
  border-color: var(--pb-accent3);
  background: rgba(54, 255, 201, 0.12);
  color: var(--pb-accent3);
}
.quiz-option.incorrect {
  border-color: #ff6464;
  background: rgba(255, 100, 100, 0.1);
  color: #ff6464;
}
.quiz-option.disabled { cursor: default; opacity: 0.8; }

.quiz-feedback {
  padding: 16px;
  border-radius: 14px;
  margin-bottom: 20px;
  font-size: 0.95rem;
}
.quiz-feedback.correct {
  background: rgba(54, 255, 201, 0.12);
  border: 1px solid rgba(54, 255, 201, 0.3);
  color: var(--pb-accent3);
}
.quiz-feedback.incorrect {
  background: rgba(255, 100, 100, 0.1);
  border: 1px solid rgba(255, 100, 100, 0.3);
  color: #ff6464;
}

.quiz-actions { display: flex; gap: 12px; flex-wrap: wrap; }

.quiz-results {
  padding: 28px;
  border-radius: 20px;
  border: 1px solid var(--pb-line);
  background: linear-gradient(145deg, rgba(126, 224, 255, 0.08), rgba(138, 108, 255, 0.06));
}
.quiz-results-title { margin: 0 0 16px; font-size: 1.5rem; }
.quiz-score {
  font-size: 2.5rem;
  font-weight: 800;
  color: var(--pb-accent);
  margin-bottom: 16px;
}
.quiz-message {
  margin: 0 0 24px;
  color: var(--pb-muted);
  font-size: 1.05rem;
  line-height: 1.6;
}

.footer {
  margin: 40px 0 10px;
  padding: 24px;
  text-align: center;
  color: var(--pb-muted);
  border-top: 1px solid var(--pb-line);
}

@media (max-width: 1100px) {
  .layout { grid-template-columns: 1fr; }
  .sidebar { position: relative; height: auto; border-right: 0; border-bottom: 1px solid var(--pb-line); }
  .hero-grid, .grid-4 { grid-template-columns: repeat(2, minmax(0, 1fr)); }
  .org-row { grid-template-columns: repeat(2, minmax(0, 1fr)); }
}

@media (max-width: 760px) {
  .content { padding: 18px; }
  .hero, .section { padding: 22px; }
  .grid-2, .grid-3, .grid-4, .hero-grid { grid-template-columns: 1fr; }
  .timeline-item { grid-template-columns: 1fr; }
  .org-row { grid-template-columns: 1fr; }
}