/* ===========================
   Book-GPTs — Premium SaaS CSS
   =========================== */

:root {
  --primary: #6C47FF;
  --primary-dark: #5535E0;
  --primary-light: #EDE9FF;
  --accent: #FF7A45;
  --dark: #0D0D1A;
  --dark-2: #14142B;
  --dark-3: #1E1E3F;
  --text: #E8E8F0;
  --text-muted: #9090B0;
  --surface: #1A1A32;
  --surface-2: #222242;
  --border: rgba(255,255,255,0.08);
  --radius: 16px;
  --radius-sm: 8px;
  --shadow: 0 4px 40px rgba(108,71,255,0.18);
  --font: 'Inter', system-ui, -apple-system, sans-serif;
  --transition: 0.22s cubic-bezier(.4,0,.2,1);
}

*, *::before, *::after { box-sizing: border-box; margin: 0; padding: 0; }

html { scroll-behavior: smooth; }

body {
  font-family: var(--font);
  background: var(--dark);
  color: var(--text);
  line-height: 1.6;
  overflow-x: hidden;
}

/* ---------- Typography ---------- */
h1, h2, h3, h4 { line-height: 1.2; font-weight: 700; }
h1 { font-size: clamp(2.2rem, 5vw, 4rem); }
h2 { font-size: clamp(1.6rem, 3.5vw, 2.6rem); }
h3 { font-size: 1.25rem; }
p { color: var(--text-muted); font-size: 1.05rem; }

.gradient-text {
  background: linear-gradient(135deg, #6C47FF 0%, #C084FC 50%, #FF7A45 100%);
  -webkit-background-clip: text;
  -webkit-text-fill-color: transparent;
  background-clip: text;
}

/* ---------- Layout ---------- */
.container {
  max-width: 1160px;
  margin: 0 auto;
  padding: 0 24px;
}

section { padding: 96px 0; }

/* ---------- Buttons ---------- */
.btn {
  display: inline-flex;
  align-items: center;
  gap: 8px;
  font-family: var(--font);
  font-weight: 600;
  font-size: 1rem;
  border: none;
  cursor: pointer;
  text-decoration: none;
  border-radius: 50px;
  transition: var(--transition);
}

.btn-primary {
  background: linear-gradient(135deg, var(--primary) 0%, #9B59F5 100%);
  color: #fff;
  padding: 16px 36px;
  box-shadow: 0 4px 24px rgba(108,71,255,0.4);
}

.btn-primary:hover {
  transform: translateY(-2px);
  box-shadow: 0 8px 36px rgba(108,71,255,0.55);
}

.btn-secondary {
  background: transparent;
  color: var(--text);
  padding: 14px 32px;
  border: 1.5px solid var(--border);
}

.btn-secondary:hover {
  background: var(--surface);
  border-color: var(--primary);
  color: #fff;
}

.btn-lg {
  font-size: 1.15rem;
  padding: 20px 48px;
}

/* ---------- Nav ---------- */
.main-nav {
  position: fixed;
  top: 0; left: 0; right: 0;
  z-index: 100;
  padding: 18px 0;
  background: rgba(13,13,26,0.7);
  backdrop-filter: blur(20px);
  -webkit-backdrop-filter: blur(20px);
  border-bottom: 1px solid var(--border);
  transition: var(--transition);
}

.nav-inner {
  display: flex;
  align-items: center;
  justify-content: space-between;
}

.logo {
  font-size: 1.3rem;
  font-weight: 800;
  color: #fff;
  text-decoration: none;
  letter-spacing: -0.5px;
}

.logo span { color: var(--primary); }

.nav-links {
  display: flex;
  align-items: center;
  gap: 32px;
  list-style: none;
}

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

.nav-links a:hover { color: #fff; }

.nav-cta { display: flex; align-items: center; gap: 12px; }

/* ---------- Hamburger ---------- */
.hamburger {
  display: none;
  flex-direction: column;
  justify-content: center;
  gap: 5px;
  cursor: pointer;
  background: none;
  border: none;
  padding: 6px;
  z-index: 200;
}

.hamburger span {
  display: block;
  width: 24px;
  height: 2px;
  background: var(--text);
  border-radius: 2px;
  transition: transform 0.28s ease, opacity 0.28s ease;
  transform-origin: center;
}

/* Animated X state */
.hamburger.is-open span:nth-child(1) { transform: translateY(7px) rotate(45deg); }
.hamburger.is-open span:nth-child(2) { opacity: 0; transform: scaleX(0); }
.hamburger.is-open span:nth-child(3) { transform: translateY(-7px) rotate(-45deg); }

/* ---------- Mobile drawer ---------- */
.mobile-menu {
  display: none;
  position: fixed;
  inset: 0;
  z-index: 150;
  background: rgba(13,13,26,0.98);
  backdrop-filter: blur(20px);
  -webkit-backdrop-filter: blur(20px);
  flex-direction: column;
  align-items: center;
  justify-content: center;
  gap: 32px;
  opacity: 0;
  transition: opacity 0.25s ease;
}

.mobile-menu.is-open {
  display: flex;
  opacity: 1;
}

.mobile-menu ul {
  list-style: none;
  display: flex;
  flex-direction: column;
  align-items: center;
  gap: 28px;
  text-align: center;
}

.mobile-menu a {
  color: var(--text);
  text-decoration: none;
  font-size: 1.5rem;
  font-weight: 600;
  transition: color var(--transition);
}

.mobile-menu a:hover { color: var(--primary); }

.mobile-menu .btn { font-size: 1rem; padding: 16px 36px; margin-top: 8px; }

/* ---------- Hero ---------- */
#hero {
  padding-top: 160px;
  padding-bottom: 96px;
  position: relative;
  overflow: hidden;
  text-align: center;
}

.hero-bg {
  position: absolute;
  inset: 0;
  background:
    radial-gradient(ellipse 80% 60% at 50% -10%, rgba(108,71,255,0.28) 0%, transparent 70%),
    radial-gradient(ellipse 50% 40% at 80% 80%, rgba(255,122,69,0.12) 0%, transparent 60%);
  pointer-events: none;
}

.hero-badge {
  display: inline-flex;
  align-items: center;
  gap: 8px;
  background: var(--surface);
  border: 1px solid var(--border);
  border-radius: 50px;
  padding: 6px 16px;
  font-size: 0.85rem;
  color: var(--text-muted);
  margin-bottom: 28px;
}

.hero-badge .dot {
  width: 8px; height: 8px;
  background: #4ADE80;
  border-radius: 50%;
  display: inline-block;
}

#hero h1 { margin-bottom: 24px; max-width: 820px; margin-left: auto; margin-right: auto; }

#hero .subtitle {
  font-size: 1.2rem;
  max-width: 580px;
  margin: 0 auto 40px;
  line-height: 1.75;
}

.hero-cta {
  display: flex;
  flex-wrap: wrap;
  gap: 16px;
  justify-content: center;
  margin-bottom: 64px;
}

.hero-stats {
  display: flex;
  justify-content: center;
  gap: 48px;
  flex-wrap: wrap;
}

.stat { text-align: center; }
.stat-number {
  font-size: 2rem;
  font-weight: 800;
  color: #fff;
  display: block;
}
.stat-label { font-size: 0.85rem; color: var(--text-muted); }

/* Hero card preview */
.hero-preview {
  margin-top: 72px;
  position: relative;
  max-width: 860px;
  margin-left: auto;
  margin-right: auto;
}

.preview-card {
  background: var(--surface);
  border: 1px solid var(--border);
  border-radius: var(--radius);
  padding: 32px;
  text-align: left;
  box-shadow: var(--shadow);
}

.preview-card-header {
  display: flex;
  align-items: center;
  gap: 12px;
  margin-bottom: 20px;
}

.preview-icon {
  width: 44px; height: 44px;
  border-radius: 10px;
  background: linear-gradient(135deg, var(--primary), #9B59F5);
  display: flex;
  align-items: center;
  justify-content: center;
  font-size: 1.3rem;
}

.preview-book-title { color: #fff; font-weight: 600; }
.preview-book-author { font-size: 0.85rem; color: var(--text-muted); }

.preview-tags {
  display: flex;
  gap: 8px;
  flex-wrap: wrap;
  margin-bottom: 16px;
}

.tag {
  background: rgba(108,71,255,0.15);
  color: #C084FC;
  border: 1px solid rgba(108,71,255,0.3);
  padding: 4px 12px;
  border-radius: 50px;
  font-size: 0.8rem;
  font-weight: 500;
}

.preview-text { color: var(--text-muted); font-size: 0.95rem; line-height: 1.7; }

.preview-glow {
  position: absolute;
  bottom: -60px;
  left: 50%;
  transform: translateX(-50%);
  width: 60%;
  height: 120px;
  background: var(--primary);
  filter: blur(80px);
  opacity: 0.2;
  pointer-events: none;
}

/* ---------- Logos / Trust bar ---------- */
#trust {
  padding: 40px 0;
  border-top: 1px solid var(--border);
  border-bottom: 1px solid var(--border);
}

.trust-label {
  text-align: center;
  font-size: 0.85rem;
  color: var(--text-muted);
  margin-bottom: 24px;
  text-transform: uppercase;
  letter-spacing: 1px;
}

.trust-logos {
  display: flex;
  align-items: center;
  justify-content: center;
  gap: 48px;
  flex-wrap: wrap;
  opacity: 0.5;
  filter: grayscale(1);
}

.trust-item { font-size: 1.1rem; font-weight: 700; color: var(--text); }

/* ---------- Benefits ---------- */
#benefits { background: var(--dark); }

.section-label {
  font-size: 0.8rem;
  font-weight: 700;
  letter-spacing: 2px;
  text-transform: uppercase;
  color: var(--primary);
  margin-bottom: 12px;
  display: block;
}

.section-header { text-align: center; margin-bottom: 64px; }
.section-header p { max-width: 560px; margin: 16px auto 0; }

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

.benefit-card {
  background: var(--surface);
  border: 1px solid var(--border);
  border-radius: var(--radius);
  padding: 32px;
  transition: var(--transition);
  position: relative;
  overflow: hidden;
}

.benefit-card::before {
  content: '';
  position: absolute;
  top: 0; left: 0; right: 0;
  height: 3px;
  background: linear-gradient(90deg, var(--primary), #9B59F5);
  opacity: 0;
  transition: var(--transition);
}

.benefit-card:hover { border-color: rgba(108,71,255,0.4); transform: translateY(-4px); }
.benefit-card:hover::before { opacity: 1; }

.benefit-icon {
  width: 52px; height: 52px;
  border-radius: 12px;
  background: var(--primary-light);
  display: flex;
  align-items: center;
  justify-content: center;
  font-size: 1.5rem;
  margin-bottom: 20px;
}

.benefit-card h3 { color: #fff; margin-bottom: 10px; }

/* ---------- How it works ---------- */
#how {
  background: linear-gradient(180deg, var(--dark) 0%, var(--dark-2) 100%);
  position: relative;
}

.steps {
  display: grid;
  grid-template-columns: repeat(3, 1fr);
  gap: 40px;
  position: relative;
}

.steps::before {
  content: '';
  position: absolute;
  top: 36px;
  left: calc(16.66% + 24px);
  right: calc(16.66% + 24px);
  height: 2px;
  background: linear-gradient(90deg, var(--primary), #9B59F5, var(--primary));
  opacity: 0.3;
}

.step { text-align: center; position: relative; }

.step-number {
  width: 72px; height: 72px;
  border-radius: 50%;
  background: linear-gradient(135deg, var(--primary), #9B59F5);
  display: flex;
  align-items: center;
  justify-content: center;
  font-size: 1.6rem;
  margin: 0 auto 24px;
  box-shadow: 0 0 0 8px rgba(108,71,255,0.12);
}

.step h3 { color: #fff; margin-bottom: 10px; }

/* ---------- Use cases ---------- */
#usecases { background: var(--dark); }

.usecases-grid {
  display: grid;
  grid-template-columns: repeat(2, 1fr);
  gap: 24px;
}

.usecase-card {
  background: var(--surface);
  border: 1px solid var(--border);
  border-radius: var(--radius);
  padding: 32px;
  display: flex;
  gap: 20px;
  transition: var(--transition);
}

.usecase-card:hover { border-color: rgba(108,71,255,0.4); }

.usecase-emoji { font-size: 2.4rem; flex-shrink: 0; }
.usecase-card h3 { color: #fff; margin-bottom: 8px; }

/* ---------- Features ---------- */
#features {
  background: var(--dark-2);
}

.features-layout {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: 80px;
  align-items: center;
}

.features-list { display: flex; flex-direction: column; gap: 24px; }

.feature-item {
  display: flex;
  gap: 16px;
  padding: 20px;
  border-radius: var(--radius-sm);
  border: 1px solid transparent;
  transition: var(--transition);
  cursor: default;
}

.feature-item:hover {
  background: var(--surface);
  border-color: var(--border);
}

.feature-item-icon {
  width: 44px; height: 44px;
  border-radius: 10px;
  background: rgba(108,71,255,0.15);
  border: 1px solid rgba(108,71,255,0.3);
  display: flex;
  align-items: center;
  justify-content: center;
  font-size: 1.2rem;
  flex-shrink: 0;
}

.feature-item h3 { color: #fff; font-size: 1rem; margin-bottom: 4px; }
.feature-item p { font-size: 0.9rem; }

.features-visual {
  background: var(--surface);
  border: 1px solid var(--border);
  border-radius: var(--radius);
  padding: 32px;
  box-shadow: var(--shadow);
}

.analysis-block {
  background: var(--dark-3);
  border-radius: var(--radius-sm);
  padding: 16px;
  margin-bottom: 16px;
}

.analysis-block:last-child { margin-bottom: 0; }
.analysis-label { font-size: 0.75rem; text-transform: uppercase; letter-spacing: 1px; color: var(--primary); margin-bottom: 8px; font-weight: 600; }
.analysis-content { color: var(--text); font-size: 0.9rem; line-height: 1.6; }

.score-bar { height: 6px; background: var(--dark); border-radius: 3px; margin-top: 8px; overflow: hidden; }
.score-fill { height: 100%; border-radius: 3px; background: linear-gradient(90deg, var(--primary), #C084FC); }

/* ---------- FAQ ---------- */
#faq { background: var(--dark); }

.faq-grid { max-width: 760px; margin: 0 auto; display: flex; flex-direction: column; gap: 16px; }

.faq-item {
  background: var(--surface);
  border: 1px solid var(--border);
  border-radius: var(--radius-sm);
  overflow: hidden;
}

.faq-question {
  width: 100%;
  background: none;
  border: none;
  color: #fff;
  font-family: var(--font);
  font-size: 1rem;
  font-weight: 600;
  text-align: left;
  padding: 20px 24px;
  cursor: pointer;
  display: flex;
  justify-content: space-between;
  align-items: center;
  gap: 16px;
  transition: var(--transition);
}

.faq-question:hover { background: var(--surface-2); }

.faq-chevron {
  font-size: 1.1rem;
  transition: transform var(--transition);
  color: var(--primary);
  flex-shrink: 0;
}

.faq-item.open .faq-chevron { transform: rotate(180deg); }

.faq-answer {
  display: none;
  padding: 0 24px 20px;
  color: var(--text-muted);
  font-size: 0.95rem;
  line-height: 1.7;
}

.faq-item.open .faq-answer { display: block; }

/* ---------- Final CTA ---------- */
#cta-final {
  background: var(--dark-2);
  text-align: center;
  position: relative;
  overflow: hidden;
}

.cta-bg {
  position: absolute;
  inset: 0;
  background: radial-gradient(ellipse 80% 80% at 50% 50%, rgba(108,71,255,0.18) 0%, transparent 70%);
  pointer-events: none;
}

#cta-final h2 { margin-bottom: 16px; }
#cta-final p { max-width: 520px; margin: 0 auto 40px; }

/* ---------- Footer ---------- */
footer {
  background: var(--dark);
  border-top: 1px solid var(--border);
  padding: 48px 0 32px;
}

.footer-inner {
  display: flex;
  flex-wrap: wrap;
  justify-content: space-between;
  align-items: flex-start;
  gap: 32px;
  margin-bottom: 40px;
}

.footer-brand { max-width: 300px; }
.footer-brand p { font-size: 0.9rem; margin-top: 12px; }

.footer-links { display: flex; gap: 48px; flex-wrap: wrap; }
.footer-col h4 { color: #fff; font-size: 0.9rem; margin-bottom: 16px; }
.footer-col ul { list-style: none; display: flex; flex-direction: column; gap: 10px; }
.footer-col a { color: var(--text-muted); text-decoration: none; font-size: 0.88rem; transition: color var(--transition); }
.footer-col a:hover { color: #fff; }

.footer-bottom {
  border-top: 1px solid var(--border);
  padding-top: 24px;
  display: flex;
  justify-content: space-between;
  align-items: center;
  flex-wrap: wrap;
  gap: 12px;
}

.footer-bottom p { font-size: 0.85rem; }

/* ---------- Responsive ---------- */
@media (max-width: 900px) {
  .benefits-grid { grid-template-columns: repeat(2, 1fr); }
  .steps { grid-template-columns: 1fr; gap: 40px; }
  .steps::before { display: none; }
  .features-layout { grid-template-columns: 1fr; gap: 40px; }
  .usecases-grid { grid-template-columns: 1fr; }
}

@media (max-width: 768px) {
  /* Hide desktop nav items, show hamburger */
  .nav-links { display: none; }
  .nav-cta { display: none; }
  .hamburger { display: flex; }
}

@media (max-width: 640px) {
  section { padding: 64px 0; }
  .benefits-grid { grid-template-columns: 1fr; }
  .hero-stats { gap: 28px; }
  .footer-links { gap: 28px; }
  .footer-inner { flex-direction: column; }
  .footer-bottom { flex-direction: column; text-align: center; }
}