/* =========================================================
   Stack Cards — Landing Page
   Baseado no Design System oficial
   ========================================================= */

/* ---------- 1. TOKENS ---------- */
:root {
  /* Cores — tema claro */
  --bg-primary: #f7f4ed;
  --bg-secondary: #fffefa;
  --bg-tertiary: #efeade;
  --bg-elevated: #ffffff;
  --text-primary: #1a1612;
  --text-secondary: #52463a;
  --text-tertiary: #8a7a68;
  --text-inverse: #f7f4ed;
  --border-subtle: #e4dcc9;
  --border-medium: #c9bfa8;
  --border-strong: #1a1612;
  --accent: #c2410c;
  --accent-hover: #9a330a;
  --accent-soft: #fef3e8;

  /* Estados semânticos */
  --wrong: #b91c1c;
  --wrong-soft: #fde8e8;
  --hard: #c2410c;
  --hard-soft: #fef3e8;
  --good: #0f766e;
  --good-soft: #e6f4f1;
  --easy: #365314;
  --easy-soft: #eef5e3;

  /* Tipografia */
  --font-display: 'Fraunces', Georgia, serif;
  --font-body: 'Inter', -apple-system, BlinkMacSystemFont, sans-serif;
  --font-mono: 'JetBrains Mono', 'Courier New', monospace;

  /* Layout */
  --max-width: 1200px;
  --radius-sm: 6px;
  --radius-md: 12px;
  --radius-lg: 20px;

  /* Sombras */
  --shadow-sm: 0 1px 2px rgba(26, 22, 18, 0.04), 0 2px 4px rgba(26, 22, 18, 0.04);
  --shadow-md: 0 4px 6px rgba(26, 22, 18, 0.05), 0 10px 15px rgba(26, 22, 18, 0.06);
  --shadow-lg: 0 10px 20px rgba(26, 22, 18, 0.06), 0 20px 40px rgba(26, 22, 18, 0.08);
  --shadow-card: 0 1px 3px rgba(26, 22, 18, 0.05), 0 4px 12px rgba(26, 22, 18, 0.04);

  /* Motion */
  --trans-fast: 150ms ease;
  --trans-medium: 280ms cubic-bezier(0.4, 0, 0.2, 1);
  --trans-slow: 500ms cubic-bezier(0.4, 0, 0.2, 1);
}

[data-theme="dark"] {
  --bg-primary: #14110d;
  --bg-secondary: #1c1814;
  --bg-tertiary: #25201a;
  --bg-elevated: #1f1b16;
  --text-primary: #f0e9dd;
  --text-secondary: #b8ab96;
  --text-tertiary: #6e6456;
  --text-inverse: #14110d;
  --border-subtle: #2e2820;
  --border-medium: #3d362c;
  --border-strong: #f0e9dd;
  --accent: #f97316;
  --accent-hover: #fb923c;
  --accent-soft: #2a1a0e;

  --wrong: #f87171;
  --wrong-soft: #2b1515;
  --hard: #fb923c;
  --hard-soft: #2a1a0e;
  --good: #5eead4;
  --good-soft: #0f1f1e;
  --easy: #a3e635;
  --easy-soft: #1a2410;

  --shadow-sm: 0 1px 2px rgba(0, 0, 0, 0.3);
  --shadow-md: 0 4px 12px rgba(0, 0, 0, 0.4);
  --shadow-lg: 0 10px 30px rgba(0, 0, 0, 0.5);
  --shadow-card: 0 1px 3px rgba(0, 0, 0, 0.3), 0 4px 12px rgba(0, 0, 0, 0.2);
}

/* ---------- 2. BASE ---------- */
*, *::before, *::after {
  box-sizing: border-box;
}

html {
  scroll-behavior: smooth;
  -webkit-text-size-adjust: 100%;
}

body {
  margin: 0;
  font-family: var(--font-body);
  font-size: 16px;
  line-height: 1.6;
  color: var(--text-primary);
  background: var(--bg-primary);
  -webkit-font-smoothing: antialiased;
  -moz-osx-font-smoothing: grayscale;
  overflow-x: hidden;
  transition: background var(--trans-medium), color var(--trans-medium);
}

img, svg { display: block; max-width: 100%; }

h1, h2, h3, h4 {
  font-family: var(--font-display);
  font-weight: 500;
  line-height: 1.15;
  letter-spacing: -0.02em;
  color: var(--text-primary);
  margin: 0;
}

p { margin: 0; }

a {
  color: inherit;
  text-decoration: none;
  transition: color var(--trans-fast);
}

button {
  font-family: inherit;
  cursor: pointer;
  border: none;
  background: none;
}

kbd {
  font-family: var(--font-mono);
  font-size: 0.8em;
  padding: 2px 6px;
  background: var(--bg-tertiary);
  border: 1px solid var(--border-subtle);
  border-radius: 4px;
  color: var(--text-secondary);
}

::selection {
  background: var(--accent);
  color: var(--text-inverse);
}

/* ---------- 3. LAYOUT ---------- */
.container {
  width: 100%;
  max-width: var(--max-width);
  margin: 0 auto;
  padding: 0 24px;
}

.section {
  padding: 96px 0;
  position: relative;
}

.section-head {
  max-width: 720px;
  margin: 0 auto 64px;
  text-align: center;
}

.eyebrow {
  font-family: var(--font-mono);
  font-size: 0.75rem;
  font-weight: 500;
  letter-spacing: 0.18em;
  text-transform: uppercase;
  color: var(--text-tertiary);
  margin-bottom: 16px;
}

.section-title {
  font-size: clamp(1.75rem, 3.5vw, 2.5rem);
  margin-bottom: 16px;
}

.section-description {
  font-size: 1.0625rem;
  color: var(--text-secondary);
  line-height: 1.7;
  max-width: 620px;
  margin: 0 auto;
}

.accent-text { color: var(--accent); }

/* ---------- 4. BACKGROUND DECORATIVO ---------- */
.bg-decoration {
  position: fixed;
  inset: 0;
  z-index: -1;
  overflow: hidden;
  pointer-events: none;
}

.grain {
  position: absolute;
  inset: 0;
  opacity: 0.04;
  background-image: url("data:image/svg+xml,%3Csvg viewBox='0 0 200 200' xmlns='http://www.w3.org/2000/svg'%3E%3Cfilter id='n'%3E%3CfeTurbulence type='fractalNoise' baseFrequency='0.9' numOctaves='3' stitchTiles='stitch'/%3E%3C/filter%3E%3Crect width='100%25' height='100%25' filter='url(%23n)'/%3E%3C/svg%3E");
  mix-blend-mode: multiply;
}

[data-theme="dark"] .grain {
  opacity: 0.08;
  mix-blend-mode: overlay;
}

.gradient-blob {
  position: absolute;
  border-radius: 50%;
  filter: blur(80px);
  opacity: 0.25;
  animation: float 20s ease-in-out infinite;
}

.gradient-blob-1 {
  width: 500px;
  height: 500px;
  background: radial-gradient(circle, var(--accent), transparent 70%);
  top: -200px;
  right: -150px;
}

.gradient-blob-2 {
  width: 400px;
  height: 400px;
  background: radial-gradient(circle, #8b5cf6, transparent 70%);
  bottom: -100px;
  left: -100px;
  animation-delay: -10s;
  opacity: 0.15;
}

[data-theme="dark"] .gradient-blob { opacity: 0.12; }

@keyframes float {
  0%, 100% { transform: translate(0, 0) scale(1); }
  33% { transform: translate(30px, -40px) scale(1.05); }
  66% { transform: translate(-20px, 20px) scale(0.95); }
}

@media (prefers-reduced-motion: reduce) {
  .gradient-blob { animation: none; }
  html { scroll-behavior: auto; }
}

/* ---------- 5. HEADER ---------- */
.site-header {
  position: sticky;
  top: 0;
  z-index: 100;
  background: rgba(247, 244, 237, 0.78);
  backdrop-filter: blur(20px) saturate(180%);
  -webkit-backdrop-filter: blur(20px) saturate(180%);
  border-bottom: 1px solid var(--border-subtle);
  transition: background var(--trans-medium), border-color var(--trans-medium);
}

[data-theme="dark"] .site-header {
  background: rgba(20, 17, 13, 0.78);
}

.header-inner {
  display: flex;
  align-items: center;
  justify-content: space-between;
  height: 64px;
  gap: 24px;
}

.brand {
  display: inline-flex;
  align-items: center;
  gap: 12px;
  color: var(--text-primary);
  transition: opacity var(--trans-fast);
}

.brand:hover { opacity: 0.85; }

.brand-mark {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  width: 32px;
  height: 32px;
  color: var(--accent);
  flex-shrink: 0;
}

.brand-mark svg { width: 100%; height: 100%; }

.brand-text {
  display: inline-flex;
  flex-direction: column;
  gap: 2px;
  line-height: 1;
  min-width: 0;
}

.brand-title {
  font-family: var(--font-display);
  font-weight: 600;
  font-size: 1.0625rem;
  color: var(--text-primary);
  letter-spacing: -0.02em;
  line-height: 1.15;
}

.brand-sub {
  font-family: var(--font-mono);
  font-size: 0.625rem;
  font-weight: 500;
  color: var(--text-tertiary);
  letter-spacing: 0.14em;
  text-transform: uppercase;
  line-height: 1.2;
}

.site-nav {
  display: flex;
  gap: 32px;
  font-size: 0.9375rem;
}

.site-nav a {
  color: var(--text-secondary);
  font-weight: 500;
  position: relative;
}

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

.header-actions {
  display: flex;
  align-items: center;
  gap: 12px;
}

.theme-toggle {
  width: 38px;
  height: 38px;
  border-radius: var(--radius-sm);
  display: inline-flex;
  align-items: center;
  justify-content: center;
  color: var(--text-secondary);
  transition: background var(--trans-fast), color var(--trans-fast);
}

.theme-toggle:hover {
  background: var(--bg-tertiary);
  color: var(--text-primary);
}

.theme-icon { width: 18px; height: 18px; }
.theme-icon-moon { display: none; }
[data-theme="dark"] .theme-icon-sun { display: none; }
[data-theme="dark"] .theme-icon-moon { display: block; }

/* ---------- 6. BOTÕES ---------- */
.btn {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  gap: 8px;
  padding: 12px 20px;
  border-radius: var(--radius-sm);
  font-family: var(--font-body);
  font-weight: 600;
  font-size: 0.9375rem;
  line-height: 1;
  letter-spacing: -0.005em;
  transition: all var(--trans-medium);
  white-space: nowrap;
  cursor: pointer;
}

.btn svg { width: 16px; height: 16px; }

.btn-primary {
  background: var(--accent);
  color: #fff;
  box-shadow: var(--shadow-sm);
}

.btn-primary:hover {
  background: var(--accent-hover);
  transform: translateY(-1px);
  box-shadow: var(--shadow-md);
}

.btn-ghost {
  background: transparent;
  color: var(--text-primary);
  border: 1px solid var(--border-medium);
}

.btn-ghost:hover {
  background: var(--bg-tertiary);
  border-color: var(--border-strong);
}

.btn-sm {
  padding: 9px 16px;
  font-size: 0.875rem;
}

.btn-lg {
  padding: 16px 28px;
  font-size: 1rem;
}

.btn-lg svg { width: 18px; height: 18px; }

/* ---------- 7. HERO ---------- */
.hero {
  padding: 64px 0 80px;
  position: relative;
}

.hero-inner {
  display: grid;
  grid-template-columns: 1.1fr 0.9fr;
  gap: 80px;
  align-items: center;
}

.hero-content { max-width: 620px; }

.hero-title {
  font-size: clamp(2.25rem, 5vw, 3.75rem);
  line-height: 1.05;
  letter-spacing: -0.03em;
  margin-bottom: 24px;
  font-weight: 500;
}

.hero-title-alt {
  font-style: italic;
  font-weight: 400;
  color: var(--text-secondary);
}

.hero-subtitle {
  font-size: 1.125rem;
  line-height: 1.6;
  color: var(--text-secondary);
  margin-bottom: 32px;
  max-width: 540px;
}

.hero-cta {
  display: flex;
  flex-direction: column;
  align-items: flex-start;
  gap: 12px;
}

.hero-microcopy {
  font-family: var(--font-mono);
  font-size: 0.75rem;
  color: var(--text-tertiary);
  letter-spacing: 0.01em;
}

/* Mock flashcard */
.hero-visual {
  position: relative;
  perspective: 1200px;
}

.mock-flashcard {
  position: relative;
  background: var(--bg-elevated);
  border: 1px solid var(--border-medium);
  border-radius: var(--radius-lg);
  padding: 32px;
  box-shadow: var(--shadow-lg);
  z-index: 3;
  transform: rotate(-1.5deg);
  transition: transform var(--trans-slow);
}

.hero-visual:hover .mock-flashcard {
  transform: rotate(0deg) translateY(-4px);
}

.mock-flashcard-meta {
  display: flex;
  justify-content: space-between;
  align-items: center;
  margin-bottom: 24px;
  font-family: var(--font-mono);
  font-size: 0.75rem;
}

.mock-category {
  color: var(--accent);
  letter-spacing: 0.15em;
  font-weight: 500;
}

.mock-interval { color: var(--text-tertiary); }

.mock-question {
  font-family: var(--font-display);
  font-size: 1.375rem;
  font-weight: 500;
  line-height: 1.35;
  color: var(--text-primary);
  margin-bottom: 20px;
  letter-spacing: -0.015em;
}

.mock-divider {
  height: 1px;
  background: var(--border-subtle);
  margin: 20px 0;
}

.mock-answer {
  font-family: var(--font-mono);
  font-size: 1rem;
  color: var(--text-secondary);
  margin-bottom: 28px;
  line-height: 1.5;
}

.mock-review-buttons {
  display: grid;
  grid-template-columns: repeat(4, 1fr);
  gap: 8px;
}

.mock-btn {
  padding: 10px 8px;
  border-radius: var(--radius-sm);
  font-family: var(--font-mono);
  font-size: 0.75rem;
  font-weight: 500;
  letter-spacing: 0.02em;
  border: 1px solid transparent;
  transition: transform var(--trans-fast);
  pointer-events: none;
}

.mock-btn-wrong { background: var(--wrong-soft); color: var(--wrong); }
.mock-btn-hard  { background: var(--hard-soft);  color: var(--hard);  }
.mock-btn-good  { background: var(--good-soft);  color: var(--good);  }
.mock-btn-easy  { background: var(--easy-soft);  color: var(--easy);  }

.mock-shadow-card {
  position: absolute;
  inset: 0;
  background: var(--bg-elevated);
  border: 1px solid var(--border-subtle);
  border-radius: var(--radius-lg);
  box-shadow: var(--shadow-md);
}

.mock-shadow-card-1 {
  transform: rotate(3deg) translateY(12px);
  z-index: 2;
  opacity: 0.7;
}

.mock-shadow-card-2 {
  transform: rotate(-4deg) translateY(24px);
  z-index: 1;
  opacity: 0.4;
}

/* ---------- 8. PROBLEMA ---------- */
.section-problem {
  background: var(--bg-secondary);
  border-top: 1px solid var(--border-subtle);
  border-bottom: 1px solid var(--border-subtle);
}

.problem-grid {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: 64px;
  align-items: center;
}

.problem-text p {
  font-size: 1.0625rem;
  line-height: 1.75;
  color: var(--text-secondary);
  margin-bottom: 20px;
}

.problem-text strong {
  color: var(--text-primary);
  font-weight: 600;
}

.problem-chart {
  background: var(--bg-elevated);
  border: 1px solid var(--border-subtle);
  border-radius: var(--radius-md);
  padding: 32px;
  box-shadow: var(--shadow-card);
}

.problem-chart svg {
  width: 100%;
  height: auto;
}

.chart-grid line {
  stroke: var(--border-subtle);
  stroke-width: 1;
}

.chart-label {
  font-family: var(--font-mono);
  font-size: 10px;
  fill: var(--text-tertiary);
}

.chart-line-wrong {
  stroke: var(--wrong);
  opacity: 0.85;
}

.chart-line-good {
  stroke: var(--good);
}

.chart-dots circle {
  fill: var(--good);
}

.chart-legend {
  display: flex;
  gap: 24px;
  margin-top: 20px;
  justify-content: center;
  flex-wrap: wrap;
}

.chart-legend-item {
  display: flex;
  align-items: center;
  gap: 8px;
  font-size: 0.8125rem;
  color: var(--text-secondary);
}

.chart-legend-dot {
  width: 10px;
  height: 10px;
  border-radius: 50%;
}

.chart-legend-dot-wrong { background: var(--wrong); }
.chart-legend-dot-good  { background: var(--good); }

.chart-citation {
  text-align: center;
  font-family: var(--font-mono);
  font-size: 0.6875rem;
  color: var(--text-tertiary);
  margin-top: 12px;
  letter-spacing: 0.05em;
}

/* ---------- 9. SOLUÇÃO / PROGRESSÃO ---------- */
.progression-wrapper {
  max-width: 780px;
  margin: 0 auto;
  background: var(--bg-elevated);
  border: 1px solid var(--border-medium);
  border-radius: var(--radius-lg);
  padding: 40px;
  box-shadow: var(--shadow-card);
}

.progression-header {
  text-align: center;
  margin-bottom: 32px;
}

.progression-title {
  font-size: 1.25rem;
  font-weight: 500;
  margin-bottom: 8px;
}

.chip-inline {
  display: inline-block;
  padding: 2px 10px;
  border-radius: var(--radius-sm);
  font-family: var(--font-mono);
  font-size: 0.8125rem;
  font-weight: 500;
  vertical-align: middle;
}

.chip-good {
  background: var(--good-soft);
  color: var(--good);
}

.progression-sub {
  color: var(--text-secondary);
  font-size: 1rem;
}

.progression-table-wrap {
  overflow-x: auto;
  margin: 0 -8px;
}

.progression-table {
  width: 100%;
  border-collapse: collapse;
  font-family: var(--font-mono);
  font-size: 0.9375rem;
}

.progression-table th {
  text-align: left;
  padding: 12px 16px;
  font-size: 0.75rem;
  font-weight: 500;
  color: var(--text-tertiary);
  letter-spacing: 0.1em;
  text-transform: uppercase;
  border-bottom: 1px solid var(--border-subtle);
}

.progression-table td {
  padding: 16px;
  border-bottom: 1px solid var(--border-subtle);
  color: var(--text-secondary);
}

.progression-table tr:last-child td {
  border-bottom: none;
}

.progression-table td:first-child {
  font-weight: 500;
  color: var(--text-primary);
}

.row-highlight td {
  background: var(--accent-soft);
}

.interval-badge {
  display: inline-block;
  padding: 3px 10px;
  background: var(--bg-tertiary);
  border-radius: var(--radius-sm);
  font-size: 0.8125rem;
  color: var(--text-primary);
}

.interval-badge-strong {
  background: var(--accent);
  color: #fff;
}

.progression-footnote {
  text-align: center;
  margin-top: 32px;
  font-family: var(--font-display);
  font-style: italic;
  font-size: 1.0625rem;
  color: var(--text-secondary);
}

/* ---------- 10. CIÊNCIA ---------- */
.section-science {
  background: var(--bg-secondary);
  border-top: 1px solid var(--border-subtle);
  border-bottom: 1px solid var(--border-subtle);
}

.science-grid {
  display: grid;
  grid-template-columns: repeat(3, 1fr);
  gap: 24px;
}

.science-card {
  background: var(--bg-elevated);
  border: 1px solid var(--border-subtle);
  border-radius: var(--radius-md);
  padding: 32px;
  transition: transform var(--trans-medium), box-shadow var(--trans-medium), border-color var(--trans-medium);
  display: flex;
  flex-direction: column;
}

.science-card:hover {
  transform: translateY(-4px);
  box-shadow: var(--shadow-md);
  border-color: var(--border-medium);
}

.science-card-featured {
  border: 1px solid var(--border-strong);
  box-shadow: var(--shadow-md);
}

[data-theme="dark"] .science-card-featured {
  background: var(--bg-tertiary);
}

.science-card-head {
  padding-bottom: 20px;
  margin-bottom: 20px;
  border-bottom: 1px solid var(--border-subtle);
}

.science-year {
  display: inline-block;
  font-family: var(--font-mono);
  font-size: 0.75rem;
  letter-spacing: 0.1em;
  color: var(--accent);
  background: var(--accent-soft);
  padding: 4px 10px;
  border-radius: var(--radius-sm);
  margin-bottom: 16px;
}

.science-card-title {
  font-size: 1.375rem;
  margin-bottom: 4px;
}

.science-author {
  font-family: var(--font-mono);
  font-size: 0.8125rem;
  color: var(--text-tertiary);
  letter-spacing: 0.02em;
}

.science-card-body p {
  font-size: 0.9375rem;
  line-height: 1.65;
  color: var(--text-secondary);
  margin-bottom: 12px;
}

.science-card-body p:last-child { margin-bottom: 0; }

.science-card-body strong {
  color: var(--text-primary);
  font-weight: 600;
}

/* ---------- 11. COMO FUNCIONA ---------- */
.steps-list {
  list-style: none;
  padding: 0;
  margin: 0;
  display: grid;
  grid-template-columns: repeat(3, 1fr);
  gap: 40px;
  position: relative;
}

.step {
  padding: 0 8px;
  position: relative;
}

.step-number {
  display: inline-block;
  font-family: var(--font-mono);
  font-size: 0.75rem;
  font-weight: 500;
  color: var(--accent);
  letter-spacing: 0.1em;
  padding: 4px 10px;
  border: 1px solid var(--accent);
  border-radius: 20px;
  margin-bottom: 20px;
}

.step-title {
  font-size: 1.375rem;
  margin-bottom: 12px;
}

.step-description {
  font-size: 0.9375rem;
  line-height: 1.65;
  color: var(--text-secondary);
}

.cta-inline {
  margin-top: 56px;
  text-align: center;
}

/* ---------- 12. FUNCIONALIDADES ---------- */
.section-features {
  background: var(--bg-secondary);
  border-top: 1px solid var(--border-subtle);
  border-bottom: 1px solid var(--border-subtle);
}

.features-grid {
  display: grid;
  grid-template-columns: repeat(3, 1fr);
  gap: 24px;
}

.feature {
  background: var(--bg-elevated);
  border: 1px solid var(--border-subtle);
  border-radius: var(--radius-md);
  padding: 28px;
  transition: border-color var(--trans-fast), transform var(--trans-medium);
}

.feature:hover {
  border-color: var(--border-medium);
  transform: translateY(-2px);
}

.feature-icon {
  width: 40px;
  height: 40px;
  border-radius: var(--radius-sm);
  background: var(--accent-soft);
  color: var(--accent);
  display: inline-flex;
  align-items: center;
  justify-content: center;
  margin-bottom: 16px;
}

.feature-icon svg { width: 20px; height: 20px; }

.feature-title {
  font-size: 1.0625rem;
  font-weight: 600;
  font-family: var(--font-body);
  margin-bottom: 6px;
  letter-spacing: -0.01em;
}

.feature-description {
  font-size: 0.875rem;
  line-height: 1.55;
  color: var(--text-secondary);
}

/* ---------- 13. AGENTE DE IA ---------- */
.section-ai {
  background: var(--bg-primary);
  position: relative;
  overflow: hidden;
}

.section-ai::before {
  content: '';
  position: absolute;
  top: 0;
  left: 50%;
  transform: translateX(-50%);
  width: 80%;
  max-width: 1000px;
  height: 1px;
  background: linear-gradient(to right, transparent, var(--border-medium), transparent);
}

.ai-inner {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: 64px;
  align-items: center;
}

.ai-content .section-title {
  text-align: left;
  margin-bottom: 20px;
}

.ai-content .eyebrow {
  margin-bottom: 16px;
}

.ai-description {
  font-size: 1rem;
  line-height: 1.7;
  color: var(--text-secondary);
  margin-bottom: 28px;
}

.ai-steps {
  list-style: none;
  padding: 0;
  margin: 0 0 32px;
  display: flex;
  flex-direction: column;
  gap: 10px;
}

.ai-steps li {
  display: flex;
  align-items: center;
  gap: 12px;
  font-size: 0.9375rem;
  color: var(--text-secondary);
}

.ai-step-num {
  width: 24px;
  height: 24px;
  border-radius: 50%;
  background: var(--accent-soft);
  color: var(--accent);
  display: inline-flex;
  align-items: center;
  justify-content: center;
  font-family: var(--font-mono);
  font-size: 0.75rem;
  font-weight: 600;
  flex-shrink: 0;
}

/* Code block visual */
.ai-visual {
  position: relative;
}

.ai-code {
  background: #1a1612;
  border: 1px solid #2e2820;
  border-radius: var(--radius-md);
  overflow: hidden;
  box-shadow: var(--shadow-lg);
  transform: rotate(1deg);
  transition: transform var(--trans-slow);
}

.ai-code:hover { transform: rotate(0); }

.ai-code-head {
  display: flex;
  align-items: center;
  gap: 6px;
  padding: 12px 16px;
  background: #14110d;
  border-bottom: 1px solid #2e2820;
}

.ai-code-dot {
  width: 10px;
  height: 10px;
  border-radius: 50%;
  background: #3d362c;
}

.ai-code-filename {
  font-family: var(--font-mono);
  font-size: 0.75rem;
  color: #8a7a68;
  margin-left: 12px;
}

.ai-code-body {
  margin: 0;
  padding: 20px 24px;
  font-family: var(--font-mono);
  font-size: 0.8125rem;
  line-height: 1.75;
  color: #f0e9dd;
  overflow-x: auto;
}

.code-key     { color: #fb923c; }
.code-string  { color: #a3e635; }
.code-num     { color: #5eead4; }
.code-punct   { color: #8a7a68; }
.code-comment { color: #6e6456; font-style: italic; }

/* ---------- 14. FAQ ---------- */
.section-faq {
  background: var(--bg-secondary);
  border-top: 1px solid var(--border-subtle);
  border-bottom: 1px solid var(--border-subtle);
}

.faq-list {
  max-width: 720px;
  margin: 0 auto;
  display: flex;
  flex-direction: column;
  gap: 12px;
}

.faq-item {
  background: var(--bg-elevated);
  border: 1px solid var(--border-subtle);
  border-radius: var(--radius-md);
  overflow: hidden;
  transition: border-color var(--trans-fast);
}

.faq-item[open] {
  border-color: var(--border-medium);
}

.faq-question {
  padding: 20px 24px;
  font-family: var(--font-display);
  font-size: 1.0625rem;
  font-weight: 500;
  color: var(--text-primary);
  cursor: pointer;
  list-style: none;
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 16px;
  transition: background var(--trans-fast);
}

.faq-question::-webkit-details-marker { display: none; }

.faq-question::after {
  content: '';
  width: 12px;
  height: 12px;
  border-right: 2px solid var(--text-tertiary);
  border-bottom: 2px solid var(--text-tertiary);
  transform: rotate(45deg);
  transition: transform var(--trans-medium);
  flex-shrink: 0;
  margin-right: 4px;
  margin-top: -4px;
}

.faq-item[open] .faq-question::after {
  transform: rotate(-135deg);
  margin-top: 4px;
}

.faq-question:hover { background: var(--bg-tertiary); }

.faq-answer {
  padding: 0 24px 24px;
  color: var(--text-secondary);
  line-height: 1.7;
  font-size: 0.9375rem;
}

/* ---------- 15. CTA FINAL ---------- */
.section-final-cta { padding: 120px 0; }

.final-cta-box {
  max-width: 680px;
  margin: 0 auto;
  text-align: center;
  padding: 64px 40px;
  background: var(--bg-elevated);
  border: 1px solid var(--border-strong);
  border-radius: var(--radius-lg);
  box-shadow: var(--shadow-lg);
  position: relative;
  overflow: hidden;
}

.final-cta-box::before {
  content: '';
  position: absolute;
  top: 0;
  left: 0;
  right: 0;
  height: 4px;
  background: linear-gradient(90deg, var(--accent), #f97316, var(--accent));
}

.final-cta-title {
  font-size: clamp(1.75rem, 4vw, 2.75rem);
  margin-bottom: 12px;
}

.final-cta-sub {
  font-size: 1.0625rem;
  color: var(--text-secondary);
  margin-bottom: 32px;
}

.final-cta-micro {
  font-family: var(--font-mono);
  font-size: 0.75rem;
  color: var(--text-tertiary);
  margin-top: 20px;
  letter-spacing: 0.02em;
}

/* ---------- 16. FOOTER ---------- */
.site-footer {
  background: var(--bg-tertiary);
  border-top: 1px solid var(--border-subtle);
  padding: 56px 0 32px;
}

.footer-inner {
  display: grid;
  grid-template-columns: 1fr auto 1fr;
  gap: 32px;
  align-items: center;
}

.footer-brand {
  display: flex;
  flex-direction: column;
  gap: 8px;
}

.footer-tagline {
  font-family: var(--font-mono);
  font-size: 0.75rem;
  color: var(--text-tertiary);
  letter-spacing: 0.02em;
}

.footer-nav {
  display: flex;
  gap: 24px;
  font-size: 0.875rem;
}

.footer-nav a {
  color: var(--text-secondary);
}

.footer-nav a:hover { color: var(--text-primary); }

.footer-copy {
  font-family: var(--font-mono);
  font-size: 0.75rem;
  color: var(--text-tertiary);
  text-align: right;
}

/* ---------- 17. ACESSIBILIDADE ---------- */
:focus-visible {
  outline: 2px solid var(--accent);
  outline-offset: 2px;
  border-radius: 4px;
}

.btn:focus-visible {
  outline-offset: 3px;
}

/* ---------- 19. PÁGINA: GUIA DE IA ---------- */

/* Container mais estreito para conteúdo long-form */
.container-narrow {
  max-width: 860px;
  margin: 0 auto;
  padding: 0 24px;
}

/* Breadcrumb no topo da página */
.breadcrumb {
  padding: 24px 0 0;
  font-family: var(--font-mono);
  font-size: 0.75rem;
  letter-spacing: 0.05em;
}

.breadcrumb a {
  color: var(--text-tertiary);
  transition: color var(--trans-fast);
}

.breadcrumb a:hover { color: var(--accent); }

/* Nav ativo na página atual */
.nav-active {
  color: var(--text-primary) !important;
  position: relative;
}

.nav-active::after {
  content: '';
  position: absolute;
  bottom: -20px;
  left: 0;
  right: 0;
  height: 2px;
  background: var(--accent);
  border-radius: 2px 2px 0 0;
}

/* Hero do guia (menor que o da landing) */
.guide-hero {
  padding: 48px 0 64px;
  text-align: center;
}

.guide-hero-title {
  font-size: clamp(2rem, 4.5vw, 3.25rem);
  line-height: 1.1;
  letter-spacing: -0.03em;
  margin: 0 auto 24px;
  max-width: 820px;
  font-weight: 500;
}

.guide-hero-subtitle {
  font-size: 1.0625rem;
  line-height: 1.7;
  color: var(--text-secondary);
  max-width: 620px;
  margin: 0 auto;
}

/* Seções do guia */
.guide-section {
  padding: 72px 0;
  position: relative;
}

.guide-section-alt {
  background: var(--bg-secondary);
  border-top: 1px solid var(--border-subtle);
  border-bottom: 1px solid var(--border-subtle);
}

.guide-section-head {
  margin-bottom: 48px;
  text-align: center;
}

.guide-section-title {
  font-size: clamp(1.5rem, 3vw, 2rem);
  margin-bottom: 16px;
}

.guide-section-description {
  font-size: 1rem;
  color: var(--text-secondary);
  line-height: 1.7;
  max-width: 620px;
  margin: 0 auto;
}

/* Código inline */
.inline-code {
  font-family: var(--font-mono);
  font-size: 0.875em;
  padding: 2px 6px;
  background: var(--bg-tertiary);
  border: 1px solid var(--border-subtle);
  border-radius: 4px;
  color: var(--accent);
  white-space: nowrap;
}

[data-theme="dark"] .inline-code {
  color: var(--accent);
}

/* Casos de uso */
.use-cases {
  list-style: none;
  padding: 0;
  margin: 0;
  display: grid;
  grid-template-columns: repeat(2, 1fr);
  gap: 16px;
}

.use-case {
  display: flex;
  align-items: flex-start;
  gap: 16px;
  padding: 20px;
  background: var(--bg-elevated);
  border: 1px solid var(--border-subtle);
  border-radius: var(--radius-md);
  transition: border-color var(--trans-fast), transform var(--trans-medium);
}

.use-case:hover {
  border-color: var(--border-medium);
  transform: translateY(-2px);
}

.use-case-icon {
  width: 36px;
  height: 36px;
  border-radius: var(--radius-sm);
  background: var(--accent-soft);
  color: var(--accent);
  display: inline-flex;
  align-items: center;
  justify-content: center;
  flex-shrink: 0;
}

.use-case-icon svg { width: 18px; height: 18px; }

.use-case-title {
  font-size: 1rem;
  font-weight: 600;
  font-family: var(--font-body);
  margin: 0 0 4px;
  letter-spacing: -0.01em;
}

.use-case-description {
  font-size: 0.875rem;
  color: var(--text-secondary);
  line-height: 1.5;
}

/* Mini-steps (versão compacta dos steps) */
.mini-steps {
  list-style: none;
  padding: 0;
  margin: 0;
  display: grid;
  grid-template-columns: repeat(3, 1fr);
  gap: 20px;
}

.mini-step {
  display: flex;
  gap: 16px;
  padding: 24px;
  background: var(--bg-elevated);
  border: 1px solid var(--border-subtle);
  border-radius: var(--radius-md);
}

.mini-step-num {
  width: 32px;
  height: 32px;
  border-radius: 50%;
  background: var(--accent);
  color: #fff;
  display: inline-flex;
  align-items: center;
  justify-content: center;
  font-family: var(--font-mono);
  font-size: 0.8125rem;
  font-weight: 600;
  flex-shrink: 0;
}

.mini-step h3 {
  font-size: 1rem;
  font-family: var(--font-body);
  font-weight: 600;
  margin: 4px 0 4px;
  letter-spacing: -0.01em;
}

.mini-step p {
  font-size: 0.875rem;
  color: var(--text-secondary);
  line-height: 1.5;
}

/* Prompt box com botão copiar */
.prompt-box {
  background: #1a1612;
  border: 1px solid #2e2820;
  border-radius: var(--radius-md);
  overflow: hidden;
  box-shadow: var(--shadow-lg);
}

.prompt-box-head {
  display: flex;
  align-items: center;
  justify-content: space-between;
  padding: 12px 16px 12px 20px;
  background: #14110d;
  border-bottom: 1px solid #2e2820;
}

.prompt-box-label {
  font-family: var(--font-mono);
  font-size: 0.75rem;
  color: #8a7a68;
  letter-spacing: 0.05em;
}

.copy-btn {
  display: inline-flex;
  align-items: center;
  gap: 8px;
  padding: 8px 14px;
  border-radius: var(--radius-sm);
  background: #25201a;
  color: #f0e9dd;
  font-family: var(--font-mono);
  font-size: 0.75rem;
  font-weight: 500;
  letter-spacing: 0.02em;
  border: 1px solid #3d362c;
  transition: background var(--trans-fast), border-color var(--trans-fast), color var(--trans-fast);
}

.copy-btn:hover {
  background: #3d362c;
  border-color: #4d4637;
}

.copy-btn svg { width: 14px; height: 14px; }

.copy-icon-done,
.copy-text-done { display: none; }

.copy-btn.copied {
  background: #0f1f1e;
  color: #5eead4;
  border-color: #1a2a29;
}

.copy-btn.copied .copy-icon-default,
.copy-btn.copied .copy-text-default { display: none; }

.copy-btn.copied .copy-icon-done,
.copy-btn.copied .copy-text-done { display: inline; }

.prompt-box-body {
  margin: 0;
  padding: 24px;
  font-family: var(--font-mono);
  font-size: 0.8125rem;
  line-height: 1.7;
  color: #f0e9dd;
  white-space: pre-wrap;
  overflow-x: auto;
}

.prompt-tip {
  margin-top: 20px;
  padding: 14px 18px;
  background: var(--accent-soft);
  border: 1px solid var(--border-subtle);
  border-radius: var(--radius-sm);
  font-size: 0.875rem;
  color: var(--text-secondary);
  line-height: 1.5;
}

.prompt-tip strong { color: var(--text-primary); font-weight: 600; }

.prompt-tip a {
  color: var(--accent);
  text-decoration: underline;
  text-decoration-thickness: 1px;
  text-underline-offset: 2px;
}

/* Fluxo de exemplo (prompt → resposta → importar) */
.example-flow {
  display: flex;
  flex-direction: column;
  gap: 20px;
  align-items: stretch;
}

.example-step {
  background: var(--bg-elevated);
  border: 1px solid var(--border-subtle);
  border-radius: var(--radius-md);
  overflow: hidden;
}

.example-step-head {
  padding: 12px 20px;
  background: var(--bg-tertiary);
  border-bottom: 1px solid var(--border-subtle);
}

.example-badge {
  display: inline-block;
  font-family: var(--font-mono);
  font-size: 0.6875rem;
  font-weight: 500;
  color: var(--accent);
  letter-spacing: 0.12em;
  text-transform: uppercase;
}

.example-badge-success { color: var(--good); }

.example-prompt {
  padding: 24px;
  font-size: 0.9375rem;
  line-height: 1.7;
  color: var(--text-secondary);
}

.example-highlight {
  background: var(--accent-soft);
  color: var(--accent);
  padding: 2px 8px;
  border-radius: 4px;
  font-weight: 500;
}

.example-muted {
  color: var(--text-tertiary);
  font-style: italic;
  font-size: 0.9em;
}

.example-import {
  padding: 20px 24px;
  font-size: 0.9375rem;
  color: var(--text-secondary);
  line-height: 1.6;
}

.example-import strong { color: var(--text-primary); }

.example-step .ai-code {
  transform: none;
  border-radius: 0;
  border: none;
  box-shadow: none;
}

.example-arrow {
  display: flex;
  justify-content: center;
  color: var(--text-tertiary);
}

.example-arrow svg { width: 20px; height: 20px; }

/* Tabelas de referência */
.ref-group {
  margin-bottom: 40px;
}

.ref-group:last-child { margin-bottom: 0; }

.ref-group-title {
  font-size: 1.125rem;
  font-family: var(--font-body);
  font-weight: 600;
  letter-spacing: -0.01em;
  margin-bottom: 16px;
  color: var(--text-primary);
}

.ref-table-wrap {
  overflow-x: auto;
  background: var(--bg-elevated);
  border: 1px solid var(--border-subtle);
  border-radius: var(--radius-md);
}

.ref-table {
  width: 100%;
  border-collapse: collapse;
  font-size: 0.875rem;
}

.ref-table th {
  text-align: left;
  padding: 12px 20px;
  font-family: var(--font-mono);
  font-size: 0.6875rem;
  font-weight: 500;
  color: var(--text-tertiary);
  letter-spacing: 0.1em;
  text-transform: uppercase;
  background: var(--bg-tertiary);
  border-bottom: 1px solid var(--border-subtle);
}

.ref-table td {
  padding: 14px 20px;
  border-bottom: 1px solid var(--border-subtle);
  color: var(--text-secondary);
  vertical-align: top;
}

.ref-table tr:last-child td {
  border-bottom: none;
}

.ref-table td:nth-child(3) {
  text-align: center;
}

.req-dot {
  display: inline-block;
  width: 8px;
  height: 8px;
  border-radius: 50%;
  vertical-align: middle;
}

.req-yes { background: var(--accent); }
.req-no  { background: var(--border-medium); }

.ref-legend {
  display: flex;
  gap: 20px;
  margin-top: 12px;
  justify-content: flex-end;
  flex-wrap: wrap;
}

.ref-legend span {
  font-family: var(--font-mono);
  font-size: 0.75rem;
  color: var(--text-tertiary);
  display: inline-flex;
  align-items: center;
  gap: 6px;
}

.ref-callout {
  margin-top: 32px;
  padding: 24px 28px;
  background: var(--bg-tertiary);
  border-left: 3px solid var(--accent);
  border-radius: var(--radius-sm);
}

.ref-callout h4 {
  font-family: var(--font-body);
  font-size: 0.9375rem;
  font-weight: 600;
  letter-spacing: -0.01em;
  margin: 0 0 12px;
}

.ref-callout ul {
  list-style: none;
  padding: 0;
  margin: 0;
  display: flex;
  flex-direction: column;
  gap: 8px;
}

.ref-callout li {
  font-size: 0.875rem;
  color: var(--text-secondary);
  line-height: 1.55;
  padding-left: 16px;
  position: relative;
}

.ref-callout li::before {
  content: '→';
  position: absolute;
  left: 0;
  color: var(--accent);
  font-weight: 600;
}

.ref-callout strong { color: var(--text-primary); }

/* Lista de erros */
.error-list {
  list-style: none;
  padding: 0;
  margin: 0;
  display: flex;
  flex-direction: column;
  gap: 12px;
}

.error-list li {
  display: flex;
  align-items: flex-start;
  gap: 14px;
  padding: 18px 20px;
  background: var(--bg-elevated);
  border: 1px solid var(--border-subtle);
  border-radius: var(--radius-md);
  transition: border-color var(--trans-fast);
}

.error-list li:hover {
  border-color: var(--border-medium);
}

.error-mark {
  width: 24px;
  height: 24px;
  border-radius: 50%;
  background: var(--wrong-soft);
  color: var(--wrong);
  display: inline-flex;
  align-items: center;
  justify-content: center;
  font-weight: 700;
  font-size: 0.875rem;
  flex-shrink: 0;
  font-family: var(--font-body);
}

.error-title {
  font-size: 0.9375rem;
  font-weight: 600;
  color: var(--text-primary);
  margin: 0 0 4px;
  letter-spacing: -0.005em;
}

.error-detail {
  font-size: 0.875rem;
  color: var(--text-secondary);
  line-height: 1.5;
  margin: 0;
}

/* Lista de dicas */
.tips-list {
  list-style: none;
  padding: 0;
  margin: 0;
  display: flex;
  flex-direction: column;
  gap: 20px;
  counter-reset: tip;
}

.tip {
  display: flex;
  gap: 20px;
  padding: 24px 28px;
  background: var(--bg-elevated);
  border: 1px solid var(--border-subtle);
  border-radius: var(--radius-md);
  transition: border-color var(--trans-fast);
}

.tip:hover {
  border-color: var(--border-medium);
}

.tip-num {
  font-family: var(--font-mono);
  font-size: 1.125rem;
  font-weight: 500;
  color: var(--accent);
  letter-spacing: 0.02em;
  flex-shrink: 0;
  line-height: 1.4;
}

.tip h3 {
  font-family: var(--font-body);
  font-size: 1.0625rem;
  font-weight: 600;
  letter-spacing: -0.01em;
  margin: 0 0 6px;
}

.tip p {
  font-size: 0.9375rem;
  color: var(--text-secondary);
  line-height: 1.65;
}

.tip em {
  font-style: italic;
  color: var(--text-primary);
}

/* Toast para feedback de cópia */
.toast {
  position: fixed;
  bottom: 32px;
  left: 50%;
  transform: translateX(-50%) translateY(20px);
  background: var(--text-primary);
  color: var(--bg-primary);
  padding: 12px 20px;
  border-radius: var(--radius-sm);
  font-size: 0.875rem;
  font-family: var(--font-body);
  font-weight: 500;
  box-shadow: var(--shadow-lg);
  opacity: 0;
  pointer-events: none;
  transition: opacity var(--trans-medium), transform var(--trans-medium);
  z-index: 1000;
}

.toast.show {
  opacity: 1;
  transform: translateX(-50%) translateY(0);
}

/* ---------- 18. RESPONSIVO ---------- */
@media (max-width: 1024px) {
  .hero-inner { gap: 48px; }
  .problem-grid { gap: 48px; }
  .ai-inner { gap: 48px; }
}

@media (max-width: 768px) {
  .section { padding: 64px 0; }
  .section-head { margin-bottom: 40px; }

  .site-nav { display: none; }

  .hero { padding: 40px 0 56px; }
  .hero-inner {
    grid-template-columns: 1fr;
    gap: 48px;
  }

  .hero-visual {
    max-width: 400px;
    margin: 0 auto;
  }

  .mock-flashcard { padding: 24px; }
  .mock-question { font-size: 1.1875rem; }

  .problem-grid {
    grid-template-columns: 1fr;
    gap: 32px;
  }

  .progression-wrapper { padding: 28px 20px; }
  .progression-table { font-size: 0.8125rem; }
  .progression-table th,
  .progression-table td { padding: 12px 10px; }

  .science-grid {
    grid-template-columns: 1fr;
    gap: 16px;
  }

  .steps-list {
    grid-template-columns: 1fr;
    gap: 32px;
  }

  .features-grid {
    grid-template-columns: repeat(2, 1fr);
    gap: 16px;
  }

  .ai-inner {
    grid-template-columns: 1fr;
    gap: 40px;
  }

  .ai-visual {
    max-width: 500px;
    margin: 0 auto;
    width: 100%;
  }

  .section-final-cta { padding: 80px 0; }
  .final-cta-box { padding: 48px 24px; }

  .footer-inner {
    grid-template-columns: 1fr;
    gap: 24px;
    text-align: center;
  }
  .footer-brand { align-items: center; }
  .footer-nav { justify-content: center; flex-wrap: wrap; }
  .footer-copy { text-align: center; }

  /* Guia de IA */
  .container-narrow { padding: 0 20px; }
  .guide-section { padding: 56px 0; }
  .guide-section-head { margin-bottom: 32px; }
  .guide-hero { padding: 32px 0 48px; }

  .use-cases { grid-template-columns: 1fr; }
  .mini-steps { grid-template-columns: 1fr; }

  .prompt-box-body { padding: 18px 16px; font-size: 0.75rem; }
  .prompt-box-head { padding: 10px 12px 10px 16px; }
  .copy-btn { padding: 6px 10px; font-size: 0.6875rem; }

  .ref-table th,
  .ref-table td { padding: 10px 14px; font-size: 0.8125rem; }
  .ref-callout { padding: 20px; }
  .ref-legend { justify-content: flex-start; }

  .tip { padding: 20px; gap: 16px; flex-direction: column; }
  .tip-num { font-size: 0.9375rem; }

  .error-list li { padding: 14px 16px; gap: 12px; }

  .example-prompt,
  .example-import { padding: 18px 20px; }

  .nav-active::after { display: none; }
}

@media (max-width: 480px) {
  .container { padding: 0 20px; }
  .section { padding: 56px 0; }

  .header-actions .btn-sm { padding: 8px 12px; font-size: 0.8125rem; }

  /* Em telas muito estreitas, esconde o subtítulo da marca no header
     (mantém visível no footer, onde há espaço) */
  .site-header .brand-sub { display: none; }
  .brand-mark { width: 28px; height: 28px; }
  .brand-title { font-size: 1rem; }

  .hero-title { font-size: 2rem; }
  .section-title { font-size: 1.625rem; }

  .features-grid {
    grid-template-columns: 1fr;
  }

  .mock-review-buttons {
    grid-template-columns: repeat(2, 1fr);
  }

  .final-cta-box { padding: 40px 20px; }
  .final-cta-title { font-size: 1.625rem; }

  .ai-code-body {
    font-size: 0.75rem;
    padding: 16px;
  }
}