/* ============================================================
   Readless Landing Page — Style
   Pure black & white, minimal, high contrast
   ============================================================ */

/* ── Design Tokens ── */
:root {
  /* Dark theme (default) */
  --color-bg: #000000;
  --color-surface: #0a0a0a;
  --color-text: #ffffff;
  --color-text-secondary: #888888;
  --color-text-muted: #555555;
  --color-border: #222222;
  --color-status-green: #22c55e;
  --color-nav-bg: rgba(0, 0, 0, 0.8);
  --color-shadow: rgba(0, 0, 0, 0.4);
  --color-btn-bg: #ffffff;
  --color-btn-text: #000000;

  --font-sans: -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto,
    'Helvetica Neue', Arial, sans-serif;
  --font-mono: 'SF Mono', 'Fira Code', 'Cascadia Code', 'Menlo', monospace;

  --space-xs: 4px;
  --space-sm: 8px;
  --space-md: 16px;
  --space-lg: 24px;
  --space-xl: 32px;
  --space-2xl: 48px;
  --space-3xl: 64px;
  --space-4xl: 96px;
  --space-5xl: 120px;

  --max-width: 1080px;
  --radius-sm: 6px;
  --radius-md: 10px;
  --radius-lg: 16px;
}

/* ── Light Theme ── */
[data-theme="light"] {
  --color-bg: #ffffff;
  --color-surface: #f5f5f5;
  --color-text: #111111;
  --color-text-secondary: #555555;
  --color-text-muted: #999999;
  --color-border: #e0e0e0;
  --color-status-green: #16a34a;
  --color-nav-bg: rgba(255, 255, 255, 0.8);
  --color-shadow: rgba(0, 0, 0, 0.08);
  --color-btn-bg: #111111;
  --color-btn-text: #ffffff;
}

/* ── Theme Transition ── */
html.theme-transitioning,
html.theme-transitioning *,
html.theme-transitioning *::before,
html.theme-transitioning *::after {
  transition: background-color 0.3s ease, color 0.3s ease, border-color 0.3s ease;
  transition-duration: 0.3s;
}

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

html {
  font-size: 16px;
  scroll-behavior: smooth;
  -webkit-font-smoothing: antialiased;
  -moz-osx-font-smoothing: grayscale;
}

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

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

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

/* ── Utilities ── */
.container {
  max-width: var(--max-width);
  margin: 0 auto;
  padding: 0 var(--space-lg);
}

/* ── Scroll Animations ── */
.fade-in {
  opacity: 0;
  transform: translateY(24px);
  transition: opacity 0.7s ease, transform 0.7s ease;
}

.fade-in.visible {
  opacity: 1;
  transform: translateY(0);
}

/* ============================================================
   Navigation
   ============================================================ */
.nav {
  position: fixed;
  top: 0;
  left: 0;
  right: 0;
  z-index: 100;
  padding: var(--space-sm) 0;
  background: var(--color-nav-bg);
  backdrop-filter: blur(12px);
  -webkit-backdrop-filter: blur(12px);
  border-bottom: 1px solid transparent;
  transition: border-color 0.3s ease;
}

.nav.scrolled {
  border-bottom-color: var(--color-border);
}

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

.nav-logo {
  display: flex;
  align-items: center;
  gap: var(--space-sm);
  font-size: 1.125rem;
  font-weight: 600;
  letter-spacing: -0.02em;
}

.nav-logo-icon {
  width: 28px;
  height: 28px;
  border-radius: 6px;
}


.nav-cta {
  display: inline-flex;
  align-items: center;
  gap: var(--space-sm);
  padding: var(--space-sm) var(--space-md);
  font-size: 0.875rem;
  font-weight: 500;
  color: var(--color-btn-text);
  background: var(--color-btn-bg);
  border: none;
  border-radius: var(--radius-sm);
  cursor: pointer;
  transition: opacity 0.2s ease;
}

.nav-cta:hover {
  opacity: 0.85;
}

/* ============================================================
   Hero
   ============================================================ */
.hero {
  min-height: 100vh;
  display: flex;
  flex-direction: column;
  align-items: center;
  justify-content: center;
  text-align: center;
  padding: var(--space-5xl) var(--space-lg);
}

.hero-badge {
  display: inline-flex;
  align-items: center;
  gap: var(--space-sm);
  padding: var(--space-xs) var(--space-md);
  font-size: 0.8125rem;
  color: var(--color-text-secondary);
  border: 1px solid var(--color-border);
  border-radius: 999px;
  margin-bottom: var(--space-xl);
  letter-spacing: 0.02em;
}

.hero-badge-dot {
  width: 6px;
  height: 6px;
  border-radius: 50%;
  background: var(--color-status-green);
}

.hero h1 {
  font-size: clamp(3rem, 8vw, 5rem);
  font-weight: 700;
  letter-spacing: -0.04em;
  line-height: 1.05;
  margin-bottom: var(--space-lg);
}

.hero-tagline {
  font-size: clamp(1.125rem, 2.5vw, 1.375rem);
  color: var(--color-text-secondary);
  max-width: 560px;
  line-height: 1.5;
  margin-bottom: var(--space-2xl);
}

.hero-cta {
  display: inline-flex;
  align-items: center;
  gap: var(--space-sm);
  padding: 14px 28px;
  font-size: 1rem;
  font-weight: 500;
  font-family: var(--font-sans);
  color: var(--color-btn-text);
  background: var(--color-btn-bg);
  border: none;
  border-radius: var(--radius-sm);
  cursor: pointer;
  transition: opacity 0.2s ease, transform 0.15s ease;
}

.hero-cta:hover {
  opacity: 0.85;
  transform: translateY(-1px);
}

.hero-cta svg {
  width: 16px;
  height: 16px;
}

.hero-sub {
  margin-top: var(--space-md);
  font-size: 0.8125rem;
  color: var(--color-text-muted);
}

/* ============================================================
   Section Shared
   ============================================================ */
.section {
  padding: var(--space-5xl) 0;
}

.section-label {
  font-size: 0.75rem;
  font-weight: 600;
  letter-spacing: 0.1em;
  text-transform: uppercase;
  color: var(--color-text-muted);
  margin-bottom: var(--space-md);
}

.section-title {
  font-size: clamp(1.75rem, 4vw, 2.5rem);
  font-weight: 700;
  letter-spacing: -0.03em;
  line-height: 1.15;
  margin-bottom: var(--space-lg);
}

.section-desc {
  font-size: 1.0625rem;
  color: var(--color-text-secondary);
  max-width: 560px;
  line-height: 1.6;
}

.section-desc--center {
  margin-left: auto;
  margin-right: auto;
}

.section-desc--spaced {
  margin-bottom: var(--space-xl);
}

/* ============================================================
   How It Works
   ============================================================ */
.steps {
  display: grid;
  grid-template-columns: repeat(3, 1fr);
  gap: var(--space-xl);
  margin-top: var(--space-3xl);
}

.step {
  text-align: center;
}

.step-icon {
  width: 48px;
  height: 48px;
  margin: 0 auto var(--space-lg);
  display: flex;
  align-items: center;
  justify-content: center;
  border: 1px solid var(--color-border);
  border-radius: var(--radius-md);
  color: var(--color-text);
}

.step-icon svg {
  width: 22px;
  height: 22px;
  stroke-width: 1.5;
}

.step-number {
  font-size: 0.75rem;
  font-weight: 500;
  color: var(--color-text-muted);
  margin-bottom: var(--space-sm);
  font-family: var(--font-mono);
}

.step h3 {
  font-size: 1.125rem;
  font-weight: 600;
  margin-bottom: var(--space-sm);
  letter-spacing: -0.01em;
}

.step p {
  font-size: 0.9375rem;
  color: var(--color-text-secondary);
  line-height: 1.5;
}

/* ============================================================
   Features
   ============================================================ */
.features-grid {
  display: grid;
  grid-template-columns: repeat(2, 1fr);
  gap: 1px;
  margin-top: var(--space-3xl);
  background: var(--color-border);
  border: 1px solid var(--color-border);
  border-radius: var(--radius-lg);
  overflow: hidden;
}

.feature {
  padding: var(--space-2xl);
  background: var(--color-bg);
  transition: background 0.2s ease;
}

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

.feature-icon {
  width: 36px;
  height: 36px;
  margin-bottom: var(--space-lg);
  color: var(--color-text);
}

.feature-icon svg {
  width: 100%;
  height: 100%;
  stroke-width: 1.5;
}

.feature h3 {
  font-size: 1.0625rem;
  font-weight: 600;
  margin-bottom: var(--space-sm);
  letter-spacing: -0.01em;
}

.feature p {
  font-size: 0.9375rem;
  color: var(--color-text-secondary);
  line-height: 1.5;
}

/* Summary levels visualization */
.levels {
  display: flex;
  flex-direction: column;
  gap: var(--space-sm);
  margin-top: var(--space-md);
}

.level {
  display: flex;
  align-items: center;
  gap: var(--space-sm);
  font-size: 0.8125rem;
  font-family: var(--font-mono);
  color: var(--color-text-secondary);
}

.level-bar {
  height: 3px;
  background: var(--color-text-muted);
  border-radius: 2px;
  transition: width 0.5s ease;
}

.level:nth-child(1) .level-bar { width: 40px; }
.level:nth-child(2) .level-bar { width: 80px; }
.level:nth-child(3) .level-bar { width: 140px; }
.level:nth-child(4) .level-bar { width: 200px; }

.level-label {
  white-space: nowrap;
}

/* ============================================================
   Keyboard Section
   ============================================================ */
.keyboard-section {
  text-align: center;
}

.kbd-row {
  display: flex;
  align-items: center;
  justify-content: center;
  gap: var(--space-xl);
  margin-top: var(--space-3xl);
  flex-wrap: wrap;
}

.kbd-group {
  display: flex;
  flex-direction: column;
  align-items: center;
  gap: var(--space-md);
}

.kbd-keys {
  display: flex;
  align-items: center;
  gap: var(--space-xs);
}

kbd {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  min-width: 40px;
  height: 40px;
  padding: 0 var(--space-sm);
  font-family: var(--font-sans);
  font-size: 0.875rem;
  font-weight: 500;
  color: var(--color-text);
  background: var(--color-surface);
  border: 1px solid var(--color-border);
  border-bottom-width: 3px;
  border-radius: var(--radius-sm);
  box-shadow: 0 1px 2px var(--color-shadow);
}

.kbd-label {
  font-size: 0.875rem;
  color: var(--color-text-secondary);
}

/* keyboard press animation */
@keyframes keypress {
  0%, 100% { transform: translateY(0); border-bottom-width: 3px; }
  50% { transform: translateY(2px); border-bottom-width: 1px; }
}

.kbd-animate kbd {
  animation: keypress 2s ease-in-out infinite;
}

.kbd-group:nth-child(2) .kbd-animate kbd {
  animation-delay: 0.6s;
}

.kbd-group:nth-child(3) .kbd-animate kbd {
  animation-delay: 1.2s;
}

.kbd-group:nth-child(4) .kbd-animate kbd {
  animation-delay: 1.8s;
}

/* ============================================================
   Footer CTA
   ============================================================ */
.footer-cta {
  text-align: center;
  padding: var(--space-5xl) 0;
  border-top: 1px solid var(--color-border);
}

.footer-cta .section-title {
  margin-bottom: var(--space-lg);
}

.footer-cta-btn {
  display: inline-flex;
  align-items: center;
  gap: var(--space-sm);
  padding: 14px 32px;
  font-size: 1rem;
  font-weight: 500;
  font-family: var(--font-sans);
  color: var(--color-btn-text);
  background: var(--color-btn-bg);
  border: none;
  border-radius: var(--radius-sm);
  cursor: pointer;
  transition: opacity 0.2s ease, transform 0.15s ease;
}

.footer-cta-btn:hover {
  opacity: 0.85;
  transform: translateY(-1px);
}

.footer-cta-btn svg {
  width: 16px;
  height: 16px;
}

/* ============================================================
   Legal Pages
   ============================================================ */
.page-shell {
  padding-top: 72px;
}

.page-hero {
  max-width: 860px;
  margin: 0 auto;
  padding: calc(var(--space-5xl) + var(--space-xl)) var(--space-lg) var(--space-3xl);
}

.page-title {
  font-size: clamp(2.5rem, 6vw, 4rem);
  font-weight: 700;
  letter-spacing: -0.04em;
  line-height: 1.05;
  margin-bottom: var(--space-md);
}

.page-meta {
  font-size: 0.8125rem;
  font-family: var(--font-mono);
  color: var(--color-text-muted);
  letter-spacing: 0.04em;
  text-transform: uppercase;
  margin-bottom: var(--space-xl);
}

.page-intro {
  max-width: 720px;
  font-size: 1.0625rem;
  color: var(--color-text-secondary);
  line-height: 1.75;
}

.page-intro a,
.legal-copy a,
.page-back {
  text-decoration: underline;
  text-decoration-thickness: 1px;
  text-underline-offset: 3px;
}

.page-back {
  display: inline-flex;
  margin-top: var(--space-xl);
  font-size: 0.9375rem;
  color: var(--color-text-secondary);
}

.section--tight {
  padding-top: 0;
}

.legal-grid {
  display: grid;
  grid-template-columns: repeat(2, minmax(0, 1fr));
  gap: 1px;
  background: var(--color-border);
  border: 1px solid var(--color-border);
  border-radius: var(--radius-lg);
  overflow: hidden;
  margin-bottom: var(--space-5xl);
}

.legal-card {
  padding: var(--space-2xl);
  background: linear-gradient(180deg, var(--color-bg) 0%, var(--color-surface) 100%);
}

.legal-card h2 {
  font-size: 1.1rem;
  font-weight: 600;
  letter-spacing: -0.02em;
  margin-bottom: var(--space-md);
}

.legal-copy {
  color: var(--color-text-secondary);
}

.legal-copy p,
.legal-copy li {
  font-size: 0.9375rem;
  line-height: 1.75;
}

.legal-copy p + p {
  margin-top: var(--space-md);
}

.legal-list {
  list-style: none;
  margin-top: var(--space-md);
  display: grid;
  gap: var(--space-sm);
}

.legal-list li {
  position: relative;
  padding-left: 18px;
}

.legal-list li::before {
  content: "";
  position: absolute;
  top: 0.8em;
  left: 0;
  width: 6px;
  height: 6px;
  border-radius: 999px;
  background: var(--color-text-muted);
}

/* ============================================================
   Footer
   ============================================================ */
.footer {
  padding: var(--space-2xl) 0;
  border-top: 1px solid var(--color-border);
}

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

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

.footer-links {
  display: flex;
  gap: var(--space-lg);
}

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

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

/* ============================================================
   Toggle Switch Controls
   ============================================================ */
.nav-controls {
  display: flex;
  align-items: center;
  gap: var(--space-md);
}

.toggle-switch {
  display: flex;
  align-items: center;
  gap: 6px;
  cursor: pointer;
  user-select: none;
  -webkit-user-select: none;
  background: none;
  border: none;
  padding: 0;
  font: inherit;
}

.toggle-switch__label {
  font-size: 0.75rem;
  font-weight: 500;
  color: var(--color-text-secondary);
  letter-spacing: 0.02em;
  white-space: nowrap;
  width: 18px;
  text-align: center;
  flex-shrink: 0;
}

/* Theme toggle icon (sun/moon) — fixed size to prevent layout shift */
.toggle-switch__icon {
  position: relative;
  width: 14px;
  height: 14px;
  flex-shrink: 0;
  color: var(--color-text-secondary);
}

.toggle-switch__icon svg {
  position: absolute;
  top: 0;
  left: 0;
  transition: opacity 0.2s ease;
}

/* Dark mode: show sun, hide moon */
.toggle-switch__icon .icon-sun { opacity: 1; }
.toggle-switch__icon .icon-moon { opacity: 0; }

/* Light mode: show moon, hide sun */
[data-theme="light"] .toggle-switch__icon .icon-sun { opacity: 0; }
[data-theme="light"] .toggle-switch__icon .icon-moon { opacity: 1; }

.toggle-switch__track {
  position: relative;
  width: 36px;
  height: 20px;
  background: var(--color-border);
  border-radius: 10px;
  transition: background-color 0.2s ease;
  flex-shrink: 0;
}

.toggle-switch__thumb {
  position: absolute;
  top: 2px;
  left: 2px;
  width: 16px;
  height: 16px;
  background: var(--color-text);
  border-radius: 50%;
  transition: transform 0.2s ease;
}

.toggle-switch--active .toggle-switch__track {
  background: var(--color-text-secondary);
}

.toggle-switch--active .toggle-switch__thumb {
  transform: translateX(16px);
}

/* ============================================================
   Responsive
   ============================================================ */
@media (max-width: 768px) {
  :root {
    --space-5xl: 80px;
  }

  .steps {
    grid-template-columns: 1fr;
    gap: var(--space-2xl);
  }

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

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

  .kbd-row {
    flex-direction: column;
    gap: var(--space-2xl);
  }

  .footer-inner {
    flex-direction: column;
    gap: var(--space-md);
    text-align: center;
  }

  .hero h1 {
    font-size: clamp(2.25rem, 10vw, 3.5rem);
  }

  .page-title {
    font-size: clamp(2.1rem, 10vw, 3rem);
  }

  .level:nth-child(3) .level-bar { width: 100px; }
  .level:nth-child(4) .level-bar { width: 140px; }

  .nav-controls {
    gap: var(--space-sm);
  }

  .toggle-switch__label {
    font-size: 0.6875rem;
  }
}

@media (max-width: 480px) {
  .container {
    padding: 0 var(--space-md);
  }

  .nav-inner {
    padding: 0 var(--space-md);
  }

  .feature {
    padding: var(--space-lg);
  }

  .page-hero {
    padding-left: var(--space-md);
    padding-right: var(--space-md);
  }

  .legal-card {
    padding: var(--space-lg);
  }

  .toggle-switch__track {
    width: 30px;
    height: 17px;
  }

  .toggle-switch__thumb {
    width: 13px;
    height: 13px;
  }

  .toggle-switch--active .toggle-switch__thumb {
    transform: translateX(13px);
  }

  .nav-cta span {
    display: none;
  }
}