/* ===== Reset & Base ===== */

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

:root {
  --font: 'Inter', -apple-system, BlinkMacSystemFont, 'Segoe UI', system-ui, sans-serif;
  --color-text: #1d1d1f;
  --color-text-secondary: #6e6e73;
  --color-bg: #ffffff;
  --color-bg-light: #f5f5f7;
  --color-bg-dark: #1d1d1f;
  --color-accent: #0071e3;
  --color-accent-hover: #0077ed;
  --color-border: #d2d2d7;
  --max-width: 980px;
  --section-padding: 6rem 1.5rem;
}

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

body {
  font-family: var(--font);
  color: var(--color-text);
  background: var(--color-bg);
  line-height: 1.5;
  -webkit-font-smoothing: antialiased;
  -moz-osx-font-smoothing: grayscale;
}

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

ul {
  list-style: none;
}

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

/* ===== Nav ===== */

.nav {
  position: fixed;
  top: 0;
  left: 0;
  right: 0;
  z-index: 100;
  background: rgba(255, 255, 255, 0.8);
  backdrop-filter: saturate(180%) blur(20px);
  -webkit-backdrop-filter: saturate(180%) blur(20px);
  border-bottom: 1px solid rgba(0, 0, 0, 0.08);
}

.nav-inner {
  max-width: var(--max-width);
  margin: 0 auto;
  display: flex;
  align-items: center;
  justify-content: space-between;
  padding: 0.875rem 1.5rem;
}

.nav-logo {
  font-size: 1.25rem;
  font-weight: 700;
  letter-spacing: -0.02em;
}

.nav-links {
  display: flex;
  gap: 2rem;
}

.nav-links a {
  font-size: 0.8125rem;
  color: var(--color-text-secondary);
  transition: color 0.2s ease;
}

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

/* ===== Hero ===== */

.hero {
  min-height: 100vh;
  min-height: 100dvh;
  display: flex;
  align-items: center;
  justify-content: center;
  text-align: center;
  padding: 6rem 1.5rem 4rem;
}

.hero-inner {
  max-width: 720px;
}

.hero-eyebrow {
  font-size: 0.875rem;
  font-weight: 500;
  color: var(--color-text-secondary);
  text-transform: uppercase;
  letter-spacing: 0.1em;
  margin-bottom: 1rem;
}

.hero-title {
  font-size: clamp(3rem, 8vw, 5rem);
  font-weight: 700;
  letter-spacing: -0.03em;
  line-height: 1.05;
  margin-bottom: 1.25rem;
}

.hero-subtitle {
  font-size: clamp(1rem, 2.5vw, 1.25rem);
  color: var(--color-text-secondary);
  line-height: 1.6;
  margin-bottom: 3rem;
}

/* ===== Demo Sentence (shared) ===== */

.demo-sentence {
  display: flex;
  align-items: flex-end;
  justify-content: center;
  gap: 0.5rem;
  flex-wrap: wrap;
  padding: 2rem 0;
}

.demo-word {
  display: flex;
  flex-direction: column;
  align-items: center;
  gap: 0.125rem;
}

.demo-plain {
  font-size: clamp(1.125rem, 3vw, 1.5rem);
  color: var(--color-text-secondary);
  padding-bottom: 0;
}

.demo-word.scaffolded {
  position: relative;
}

.demo-emoji {
  font-size: clamp(1.75rem, 5vw, 2.5rem);
  line-height: 1;
  animation: float 3s ease-in-out infinite;
}

.demo-word.scaffolded:nth-child(2) .demo-emoji {
  animation-delay: 0s;
}

.demo-word.scaffolded:nth-child(4) .demo-emoji {
  animation-delay: 1.5s;
}

.demo-word.scaffolded:nth-child(5) .demo-emoji {
  animation-delay: 0.75s;
}

@keyframes float {
  0%, 100% { transform: translateY(0); }
  50% { transform: translateY(-4px); }
}

.demo-text {
  font-size: clamp(1.125rem, 3vw, 1.5rem);
  font-weight: 600;
  color: var(--color-text);
}

.demo-source {
  font-size: 0.75rem;
  font-weight: 500;
  color: var(--color-text-secondary);
  letter-spacing: 0.02em;
}

.demo-word.tri {
  gap: 0.1875rem;
}

/* ===== CTA Button / App Store Badge ===== */

.cta-button {
  display: inline-block;
  transition: opacity 0.2s ease;
}

.cta-button:hover {
  opacity: 0.8;
}

.app-store-badge {
  width: 150px;
  height: 50px;
}

/* ===== Sections (shared) ===== */

.section {
  padding: var(--section-padding);
}

.section-inner {
  max-width: var(--max-width);
  margin: 0 auto;
}

.section-title {
  font-size: clamp(1.75rem, 5vw, 3rem);
  font-weight: 700;
  letter-spacing: -0.025em;
  text-align: center;
  margin-bottom: 0.75rem;
}

.section-subtitle {
  font-size: clamp(0.9375rem, 2vw, 1.125rem);
  color: var(--color-text-secondary);
  text-align: center;
  max-width: 600px;
  margin: 0 auto 3rem;
  line-height: 1.6;
}

.section-dark {
  background: var(--color-bg-dark);
  color: #f5f5f7;
}

.section-dark .section-subtitle {
  color: #a1a1a6;
}

.section-light {
  background: var(--color-bg-light);
}

/* ===== Modes (How it works) ===== */

.modes {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(300px, 1fr));
  gap: 2rem;
}

.mode-card {
  background: var(--color-bg-light);
  border-radius: 1.25rem;
  padding: 2.5rem 2rem;
  text-align: center;
  transition: transform 0.3s ease;
}

.mode-card:hover {
  transform: translateY(-2px);
}

.mode-label {
  font-size: 1.25rem;
  font-weight: 600;
  margin-bottom: 0.5rem;
}

.mode-description {
  font-size: 0.9375rem;
  color: var(--color-text-secondary);
  margin-bottom: 1.5rem;
  line-height: 1.5;
}

.mode-demo .demo-sentence {
  padding: 1rem 0;
}

.mode-demo .demo-emoji {
  font-size: 1.75rem;
}

.mode-demo .demo-text,
.mode-demo .demo-plain {
  font-size: 1.125rem;
}

/* ===== Insight Quote ===== */

.insight-quote {
  font-size: clamp(1.25rem, 3vw, 1.75rem);
  font-weight: 500;
  text-align: center;
  max-width: 700px;
  margin: 0 auto;
  line-height: 1.5;
  letter-spacing: -0.01em;
  color: #f5f5f7;
}

/* ===== Audience Grid ===== */

.audience-grid {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(220px, 1fr));
  gap: 1.5rem;
}

.audience-card {
  text-align: center;
  padding: 2rem 1.5rem;
}

.audience-emoji {
  font-size: 2.5rem;
  display: block;
  margin-bottom: 1rem;
}

.audience-card h3 {
  font-size: 1.125rem;
  font-weight: 600;
  margin-bottom: 0.5rem;
}

.audience-card p {
  font-size: 0.875rem;
  color: var(--color-text-secondary);
  line-height: 1.6;
}

/* ===== Tiers ===== */

.tiers-grid {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(260px, 1fr));
  gap: 2rem;
}

.tier-card {
  text-align: center;
  padding: 2.5rem 2rem;
  border-radius: 1.25rem;
  background: var(--color-bg);
  transition: transform 0.3s ease;
}

.tier-card:hover {
  transform: translateY(-2px);
}

.tier-icon {
  font-size: 2.5rem;
  margin-bottom: 1rem;
  display: block;
}

.tier-icon-animated {
  animation: bounce-gentle 2s ease-in-out infinite;
}

@keyframes bounce-gentle {
  0%, 100% { transform: translateY(0); }
  50% { transform: translateY(-8px); }
}

.tier-card h3 {
  font-size: 1.125rem;
  font-weight: 600;
  margin-bottom: 0.5rem;
}

.tier-card p {
  font-size: 0.875rem;
  color: var(--color-text-secondary);
  line-height: 1.6;
}

/* ===== Features Grid ===== */

.features-grid {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(280px, 1fr));
  gap: 1.5rem;
}

.feature-card {
  padding: 2rem;
  border-radius: 1.25rem;
  background: var(--color-bg-light);
  transition: transform 0.3s ease;
}

.feature-card:hover {
  transform: translateY(-2px);
}

.feature-icon {
  font-size: 2rem;
  margin-bottom: 0.75rem;
}

.feature-card h3 {
  font-size: 1rem;
  font-weight: 600;
  margin-bottom: 0.375rem;
}

.feature-card p {
  font-size: 0.875rem;
  color: var(--color-text-secondary);
  line-height: 1.6;
}

/* ===== Languages ===== */

.languages-list {
  display: flex;
  flex-wrap: wrap;
  justify-content: center;
  gap: 0.625rem;
  max-width: 700px;
  margin: 0 auto;
}

.lang-tag {
  display: inline-block;
  padding: 0.5rem 1rem;
  border-radius: 100px;
  font-size: 0.875rem;
  font-weight: 500;
  background: rgba(255, 255, 255, 0.1);
  color: #f5f5f7;
  border: 1px solid rgba(255, 255, 255, 0.15);
  transition: background 0.2s ease;
}

.lang-tag:hover {
  background: rgba(255, 255, 255, 0.18);
}

/* ===== Comparison Table ===== */

.compare-table-wrap {
  overflow-x: auto;
  -webkit-overflow-scrolling: touch;
}

.compare-table {
  width: 100%;
  border-collapse: collapse;
  font-size: 0.875rem;
  min-width: 600px;
}

.compare-table th {
  font-weight: 500;
  color: var(--color-text-secondary);
  padding: 0.75rem 1rem;
  text-align: center;
  border-bottom: 1px solid var(--color-border);
  font-size: 0.8125rem;
}

.compare-table th:first-child {
  text-align: left;
}

.compare-table td {
  padding: 0.75rem 1rem;
  text-align: center;
  border-bottom: 1px solid rgba(0, 0, 0, 0.06);
  color: var(--color-text-secondary);
}

.compare-app {
  text-align: left !important;
  font-weight: 500;
  color: var(--color-text) !important;
}

.compare-highlight {
  background: rgba(0, 113, 227, 0.05);
}

.compare-highlight td {
  color: var(--color-accent) !important;
  font-weight: 600;
}

.compare-highlight .compare-app {
  color: var(--color-accent) !important;
}

/* ===== Pricing ===== */

.pricing-grid {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(240px, 1fr));
  gap: 1.5rem;
  max-width: 800px;
  margin: 0 auto;
}

.pricing-card {
  border-radius: 1.25rem;
  padding: 2.5rem 2rem;
  text-align: center;
  background: var(--color-bg);
  border: 1px solid var(--color-border);
  transition: transform 0.3s ease;
}

.pricing-card:hover {
  transform: translateY(-2px);
}

.pricing-featured {
  border-color: var(--color-accent);
  box-shadow: 0 0 0 1px var(--color-accent);
  position: relative;
}

.pricing-tier {
  font-size: 1rem;
  font-weight: 600;
  text-transform: uppercase;
  letter-spacing: 0.05em;
  margin-bottom: 0.75rem;
  color: var(--color-text-secondary);
}

.pricing-featured .pricing-tier {
  color: var(--color-accent);
}

.pricing-price {
  font-size: 2.5rem;
  font-weight: 700;
  letter-spacing: -0.02em;
  margin-bottom: 0.25rem;
}

.pricing-period {
  font-size: 1rem;
  font-weight: 400;
  color: var(--color-text-secondary);
}

.pricing-annual {
  font-size: 0.8125rem;
  color: var(--color-text-secondary);
  margin-bottom: 1.5rem;
}

.pricing-card:not(.pricing-featured) .pricing-price {
  margin-bottom: 1.5rem;
}

.pricing-features li {
  font-size: 0.875rem;
  color: var(--color-text-secondary);
  padding: 0.375rem 0;
  line-height: 1.5;
}

/* ===== CTA Section ===== */

.section-cta {
  text-align: center;
  padding: 8rem 1.5rem;
}

.cta-title {
  font-size: clamp(2.5rem, 7vw, 4rem);
  font-weight: 700;
  letter-spacing: -0.03em;
  margin-bottom: 0.75rem;
}

.cta-subtitle {
  font-size: clamp(1rem, 2.5vw, 1.25rem);
  color: var(--color-text-secondary);
  margin-bottom: 2.5rem;
  max-width: 500px;
  margin-left: auto;
  margin-right: auto;
}

/* ===== Footer ===== */

.footer {
  border-top: 1px solid rgba(0, 0, 0, 0.08);
  padding: 3rem 1.5rem;
}

.footer-inner {
  max-width: var(--max-width);
  margin: 0 auto;
  display: flex;
  flex-wrap: wrap;
  align-items: center;
  justify-content: space-between;
  gap: 1rem;
}

.footer-logo {
  font-size: 1rem;
  font-weight: 700;
}

.footer-tagline {
  font-size: 0.8125rem;
  color: var(--color-text-secondary);
}

.footer-links {
  display: flex;
  gap: 1.5rem;
}

.footer-link {
  font-size: 0.8125rem;
  color: var(--color-text-secondary);
  transition: color 0.2s ease;
}

.footer-link:hover {
  color: var(--color-accent);
}

.footer-copy {
  width: 100%;
  font-size: 0.75rem;
  color: var(--color-text-secondary);
  text-align: center;
  margin-top: 1rem;
}

/* ===== Privacy / Prose Page ===== */

.privacy-page {
  padding-top: 8rem;
  padding-bottom: 4rem;
}

.privacy-title {
  font-size: clamp(2rem, 5vw, 3rem);
  font-weight: 700;
  letter-spacing: -0.025em;
  margin-bottom: 0.5rem;
}

.privacy-effective {
  font-size: 0.875rem;
  color: var(--color-text-secondary);
  margin-bottom: 3rem;
}

.prose {
  max-width: 640px;
}

.prose h2 {
  font-size: 1.25rem;
  font-weight: 600;
  margin-top: 2.5rem;
  margin-bottom: 0.75rem;
}

.prose p {
  font-size: 0.9375rem;
  color: var(--color-text-secondary);
  line-height: 1.7;
  margin-bottom: 0.75rem;
}

.prose ul {
  margin-bottom: 0.75rem;
  padding-left: 1.5rem;
}

.prose li {
  font-size: 0.9375rem;
  color: var(--color-text-secondary);
  line-height: 1.7;
  position: relative;
  padding-left: 0.5rem;
  margin-bottom: 0.25rem;
}

.prose li::before {
  content: "\2022";
  position: absolute;
  left: -0.75rem;
  color: var(--color-border);
}

.inline-link {
  color: var(--color-accent);
  transition: color 0.2s ease;
}

.inline-link:hover {
  color: var(--color-accent-hover);
}

.privacy-footer-note {
  margin-top: 3rem;
  padding-top: 2rem;
  border-top: 1px solid rgba(0, 0, 0, 0.08);
}

.privacy-footer-note p {
  color: var(--color-text);
}

/* ===== Science / Article Page ===== */

.science-page {
  padding-top: 8rem;
  padding-bottom: 4rem;
}

.science-title {
  font-size: clamp(1.75rem, 4.5vw, 2.5rem);
  font-weight: 700;
  letter-spacing: -0.025em;
  line-height: 1.2;
  margin-bottom: 0.75rem;
}

.science-lede {
  font-size: 1.125rem;
  color: var(--color-text-secondary);
  line-height: 1.6;
  margin-bottom: 2rem;
}

.prose-rule {
  border: none;
  border-top: 1px solid rgba(0, 0, 0, 0.08);
  margin: 2.5rem 0;
}

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

.prose em {
  font-style: italic;
}

.citations {
  margin-top: 1.5rem;
  padding: 1.25rem 1.5rem;
  background: var(--color-bg-light);
  border-radius: 0.75rem;
}

.citations h3 {
  font-size: 0.8125rem;
  font-weight: 600;
  text-transform: uppercase;
  letter-spacing: 0.05em;
  color: var(--color-text-secondary);
  margin-bottom: 0.5rem;
}

.citations ul {
  padding-left: 0;
}

.citations li {
  font-size: 0.8125rem;
  line-height: 1.6;
  padding-left: 0;
}

.citations li::before {
  content: none;
}

.science-table th:first-child,
.science-table td:first-child {
  text-align: left;
}

.science-table td {
  font-size: 0.8125rem;
}

.science-closing {
  font-size: 1.125rem;
  font-weight: 600;
  color: var(--color-text);
  margin-top: 1.5rem;
}

.science-updated {
  font-size: 0.8125rem;
  color: var(--color-text-secondary);
}

/* ===== Responsive ===== */

@media (max-width: 768px) {
  :root {
    --section-padding: 4rem 1.25rem;
  }

  .nav-links {
    display: none;
  }

  .hero {
    padding-top: 5rem;
  }

  .demo-sentence {
    gap: 0.375rem;
  }

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

  .audience-grid {
    grid-template-columns: repeat(2, 1fr);
    gap: 1rem;
  }

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

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

  .pricing-grid {
    grid-template-columns: 1fr;
    max-width: 360px;
  }

  .footer-inner {
    flex-direction: column;
    text-align: center;
  }
}

@media (max-width: 480px) {
  .audience-grid {
    grid-template-columns: 1fr;
  }

  .section-cta {
    padding: 5rem 1.25rem;
  }
}

/* ===== Accessibility: Reduce Motion ===== */

@media (prefers-reduced-motion: reduce) {
  *,
  *::before,
  *::after {
    animation-duration: 0.01ms !important;
    animation-iteration-count: 1 !important;
    transition-duration: 0.01ms !important;
  }

  html {
    scroll-behavior: auto;
  }
}

/* ===== Print ===== */

@media print {
  .nav,
  .cta-button,
  .section-cta {
    display: none;
  }

  .section-dark {
    background: #fff;
    color: #000;
  }

  .section-dark .section-subtitle,
  .insight-quote {
    color: #333;
  }
}