/* ============================================
   ChatFold — Landing Page Styles
   Design system: Paper + Ink (from design review)
   Fonts: Instrument Serif · Inter Tight · JetBrains Mono
   ============================================ */

/* ==================== DESIGN TOKENS ==================== */
:root {
  /* Paper + ink palette */
  --paper:        #FAF8F4;
  --paper-2:      #F3EFE7;
  --paper-line:   #E7E1D3;
  --surface:      #FFFFFF;
  --ink:          #14181F;
  --ink-2:        #2A3140;
  --ink-3:        #565E70;
  --ink-4:        #8C92A1;

  /* Accent — deep editorial blue */
  --blue:         #1E48E5;
  --blue-deep:    #0E2BA8;
  --blue-tint:    #E4EAFB;
  --blue-soft:    #F1F4FE;

  /* Highlighter accents */
  --hi-yellow:    #F8E27A;
  --hi-yellow-2:  #F4D04A;
  --hi-coral:     #F26B4A;
  --hi-mint:      #C7E8D7;
  --hi-green:     #3FBE6E;

  /* Typography */
  --f-display: 'Instrument Serif', 'Times New Roman', Georgia, serif;
  --f-sans:    'Inter Tight', -apple-system, 'Helvetica Neue', sans-serif;
  --f-mono:    'JetBrains Mono', ui-monospace, 'SFMono-Regular', monospace;

  /* Shadows */
  --sh-1: 0 1px 0 rgba(20,24,31,0.04), 0 2px 8px rgba(20,24,31,0.04);
  --sh-2: 0 1px 0 rgba(20,24,31,0.06), 0 8px 24px rgba(20,24,31,0.08);
  --sh-3: 0 24px 60px -20px rgba(20,24,31,0.18), 0 8px 24px -8px rgba(20,24,31,0.10);

  /* Layout */
  --max-width: 1120px;
  --nav-height: 56px;
}

/* ==================== DARK THEME ==================== */
[data-theme="dark"] {
  --paper:        #0B0D12;
  --paper-2:      #14181F;
  --paper-line:   #2A2F3B;
  --surface:      #161A22;
  --ink:          #F4F1EA;
  --ink-2:        #C9CDD6;
  --ink-3:        #8B92A1;
  --ink-4:        #5A6172;

  --blue:         #6B8DFF;
  --blue-deep:    #A6BBFF;
  --blue-tint:    #1F2A4D;
  --blue-soft:    #161D33;

  --hi-yellow:    #F8E27A;
  --hi-yellow-2:  #F4D04A;
  --hi-coral:     #F26B4A;
  --hi-mint:      #4A8268;
  --hi-green:     #3FBE6E;

  --sh-1: 0 1px 0 rgba(0,0,0,0.5), 0 2px 8px rgba(0,0,0,0.3);
  --sh-2: 0 1px 0 rgba(0,0,0,0.6), 0 8px 24px rgba(0,0,0,0.45);
  --sh-3: 0 24px 60px -20px rgba(0,0,0,0.7), 0 8px 24px -8px rgba(0,0,0,0.5);
}

/* ==================== THEME TRANSITION ==================== */
.theme-transitioning,
.theme-transitioning *,
.theme-transitioning *::before,
.theme-transitioning *::after {
  transition:
    background-color 0.28s ease,
    border-color     0.28s ease,
    color            0.20s ease,
    box-shadow       0.28s ease !important;
}

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

html {
  scroll-behavior: smooth;
  color-scheme: light;
}
[data-theme="dark"] { color-scheme: dark; }

body {
  font-family: var(--f-sans);
  font-size: 16px;
  line-height: 1.5;
  letter-spacing: -0.011em;
  color: var(--ink-2);
  background: var(--paper);
  -webkit-font-smoothing: antialiased;
  -moz-osx-font-smoothing: grayscale;
}

img { max-width: 100%; display: block; }
a   { text-decoration: none; }

/* ==================== NAVIGATION ==================== */
.nav {
  position: fixed;
  top: 0; left: 0; right: 0;
  z-index: 100;
  height: var(--nav-height);
  background: rgba(250,248,244,0.92);
  border-bottom: 1px solid var(--paper-line);
  backdrop-filter: saturate(180%) blur(20px);
  -webkit-backdrop-filter: saturate(180%) blur(20px);
  display: flex;
  align-items: center;
  justify-content: space-between;
  padding: 0 5%;
  gap: 24px;
}
[data-theme="dark"] .nav {
  background: rgba(11,13,18,0.92);
}

.nav-logo {
  display: flex;
  align-items: center;
  gap: 9px;
  color: var(--ink);
  font-size: 17px;
  font-weight: 600;
  font-family: var(--f-sans);
  letter-spacing: -0.01em;
  flex-shrink: 0;
}
.nav-logo-mark {
  width: 28px;
  height: 28px;
  border-radius: 7px;
  background: var(--ink);
  color: var(--paper);
  display: grid;
  place-items: center;
  font-family: var(--f-display);
  font-style: italic;
  font-weight: 500;
  font-size: 16px;
  flex-shrink: 0;
  line-height: 1;
}

.nav-links {
  display: flex;
  align-items: center;
  gap: 28px;
  list-style: none;
  flex: 1;
  justify-content: center;
}
.nav-links a {
  font-family: var(--f-sans);
  font-size: 13px;
  font-weight: 400;
  color: var(--ink-3);
  letter-spacing: 0;
  transition: color 0.18s;
}
.nav-links a:hover { color: var(--ink); }

.nav-actions {
  display: flex;
  align-items: center;
  gap: 10px;
  flex-shrink: 0;
}

.nav-cta {
  font-family: var(--f-sans);
  font-size: 13px;
  font-weight: 500;
  color: var(--paper) !important;
  background: var(--ink);
  padding: 7px 16px;
  border-radius: 8px;
  white-space: nowrap;
  transition: opacity 0.18s;
}
.nav-cta:hover { opacity: 0.82; }

/* Language toggle */
.lang-toggle {
  height: 30px;
  padding: 0 10px;
  border-radius: 6px;
  background: none;
  border: 1.5px solid var(--paper-line);
  cursor: pointer;
  display: flex;
  align-items: center;
  color: var(--ink-3);
  font-family: var(--f-sans);
  font-size: 12px;
  font-weight: 500;
  transition: background 0.18s, border-color 0.18s, color 0.18s;
  white-space: nowrap;
}
.lang-toggle:hover {
  background: var(--paper-2);
  color: var(--ink);
  border-color: var(--paper-line);
}

/* Language-conditional visibility */
.show-when-zh { display: none; }
[data-lang="zh"] .show-when-en { display: none; }
[data-lang="zh"] .show-when-zh { display: inline; }

/* Theme toggle */
.theme-toggle {
  width: 30px;
  height: 30px;
  border-radius: 50%;
  background: none;
  border: 1.5px solid var(--paper-line);
  cursor: pointer;
  display: flex;
  align-items: center;
  justify-content: center;
  color: var(--ink-3);
  transition: background 0.18s, color 0.18s;
  padding: 0;
}
.theme-toggle:hover { background: var(--paper-2); color: var(--ink); }
.theme-toggle svg { width: 14px; height: 14px; }

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

/* Hamburger */
.nav-hamburger {
  display: none;
  flex-direction: column;
  gap: 5px;
  cursor: pointer;
  background: none;
  border: none;
  padding: 4px;
}
.nav-hamburger span {
  display: block;
  width: 22px;
  height: 1.5px;
  background: var(--ink);
  border-radius: 2px;
  transition: all 0.25s;
}

/* Mobile overlay */
.nav-mobile-overlay {
  display: none;
  position: fixed;
  inset: 0;
  background: rgba(250,248,244,0.97);
  z-index: 99;
  flex-direction: column;
  align-items: center;
  justify-content: center;
  gap: 36px;
  backdrop-filter: blur(12px);
}
[data-theme="dark"] .nav-mobile-overlay {
  background: rgba(11,13,18,0.97);
}
.nav-mobile-overlay.open { display: flex; }
.nav-mobile-overlay a {
  font-family: var(--f-display);
  font-style: italic;
  font-size: 28px;
  font-weight: 400;
  color: var(--ink);
}
.nav-mobile-overlay .nav-cta {
  font-family: var(--f-sans) !important;
  font-style: normal;
  font-size: 17px !important;
  padding: 12px 28px;
  border-radius: 10px;
}

/* ==================== SECTION UTILITIES ==================== */
.section-inner {
  max-width: var(--max-width);
  margin: 0 auto;
  padding: 88px 80px;
}

/* Mono section label — "↳ Label Text" style */
.section-mono-label {
  font-family: var(--f-mono);
  font-size: 11px;
  letter-spacing: 0.12em;
  text-transform: uppercase;
  color: var(--ink-3);
  margin-bottom: 14px;
}

/* Section H2 — Instrument Serif italic */
.section-h2 {
  font-family: var(--f-display);
  font-style: italic;
  font-weight: 400;
  font-size: 56px;
  line-height: 1.0;
  letter-spacing: -0.02em;
  color: var(--ink);
  margin: 0;
}

.cta-center { display: flex; justify-content: center; }

/* ==================== GLOBAL CTA BUTTON ==================== */
.cta-primary {
  display: inline-flex;
  align-items: center;
  gap: 10px;
  background: var(--ink);
  color: var(--paper);
  padding: 13px 22px;
  border-radius: 10px;
  font-family: var(--f-sans);
  font-size: 15px;
  font-weight: 500;
  box-shadow: var(--sh-2);
  transition: opacity 0.18s, transform 0.12s;
  cursor: pointer;
  white-space: nowrap;
}
.cta-primary:hover { opacity: 0.86; }
.cta-primary:active { transform: scale(0.98); }

.cta-secondary {
  font-size: 14px;
  color: var(--ink-2);
  text-decoration: underline;
  text-underline-offset: 4px;
  text-decoration-color: var(--ink-4);
  font-family: var(--f-sans);
  transition: text-decoration-color 0.18s;
}
.cta-secondary:hover { text-decoration-color: var(--ink-2); }

/* ==================== HERO ==================== */
#hero {
  padding-top: var(--nav-height);
  background: var(--paper);
  border-bottom: 1px solid var(--paper-line);
}

.hero-inner {
  max-width: var(--max-width);
  margin: 0 auto;
  padding: 64px 80px 0;
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: 64px;
  align-items: center;
}

/* Left: copy */
.hero-copy {}

.hero-eyebrow-pill {
  display: inline-flex;
  align-items: center;
  gap: 8px;
  padding: 5px 12px;
  background: var(--surface);
  border: 1px solid var(--paper-line);
  border-radius: 999px;
  margin-bottom: 22px;
  box-shadow: var(--sh-1);
}
.hero-eyebrow-dot {
  width: 6px;
  height: 6px;
  border-radius: 999px;
  background: #3FBE6E;
  flex-shrink: 0;
}
.hero-eyebrow-text {
  font-family: var(--f-mono);
  font-size: 11px;
  letter-spacing: 0.1em;
  text-transform: uppercase;
  color: var(--ink-3);
}

.hero-h1 {
  font-family: var(--f-display);
  font-style: italic;
  font-weight: 400;
  font-size: 62px;
  line-height: 0.96;
  letter-spacing: -0.025em;
  color: var(--ink);
  margin: 0 0 22px;
}
.hero-h1-highlight {
  position: relative;
  display: inline-block;
  white-space: nowrap;
}
.hero-h1-highlight-text {
  position: relative;
  z-index: 2;
}
.hero-h1-highlight-bg {
  position: absolute;
  left: -4px;
  right: -4px;
  bottom: 5px;
  height: 16px;
  background: var(--hi-yellow);
  z-index: 1;
  border-radius: 2px;
  transform: skewX(-4deg);
}

.hero-sub {
  font-size: 18px;
  line-height: 1.5;
  color: var(--ink-2);
  max-width: 460px;
  margin: 0 0 32px;
}

.hero-ctas {
  display: flex;
  align-items: center;
  gap: 18px;
  margin-bottom: 28px;
  flex-wrap: wrap;
}

.hero-social-proof {
  display: flex;
  gap: 16px;
  align-items: center;
  font-size: 12px;
  color: var(--ink-3);
  flex-wrap: wrap;
}
.hero-stars {
  display: flex;
  align-items: center;
  gap: 6px;
}
.hero-stars-row {
  display: flex;
  gap: 2px;
}
.hero-sep {
  width: 3px;
  height: 3px;
  border-radius: 999px;
  background: var(--ink-4);
}

/* Right: product illustrations */
.hero-visuals {
  position: relative;
  height: 520px;
}

.hero-annot {
  position: absolute;
  top: -18px;
  right: 8px;
  width: 130px;
  transform: rotate(8deg);
  font-family: var(--f-display);
  font-style: italic;
  color: var(--ink-3);
  font-size: 14px;
  line-height: 1.3;
  pointer-events: none;
}
.hero-annot-line {
  width: 72px;
  height: 1px;
  background: var(--ink-4);
  margin-top: 8px;
  transform: rotate(35deg);
  transform-origin: left;
}

.hero-card-back {
  position: absolute;
  top: 28px;
  left: -10px;
  transform: rotate(-2.5deg);
}
.hero-card-front {
  position: absolute;
  top: 68px;
  right: -20px;
  transform: rotate(2deg);
}

/* ── Shared product card ── */
.product-card {
  background: var(--surface);
  border-radius: 14px;
  border: 1px solid var(--paper-line);
  overflow: hidden;
}
.product-card-chat { width: 360px; box-shadow: var(--sh-2); }
.product-card-sidebar { width: 265px; box-shadow: var(--sh-3); }

.card-chrome {
  padding: 9px 14px;
  border-bottom: 1px solid var(--paper-line);
  display: flex;
  align-items: center;
  gap: 10px;
  background: var(--paper-2);
}
.chrome-dots { display: flex; gap: 5px; }
.chrome-dot {
  width: 9px; height: 9px;
  border-radius: 999px;
}
.chrome-dot-r { background: #FF6058; }
.chrome-dot-y { background: #FFC130; }
.chrome-dot-g { background: #28C84B; }
.chrome-url {
  font-family: var(--f-mono);
  font-size: 10px;
  color: var(--ink-4);
  flex: 1;
  text-align: center;
}

.chat-msgs {
  padding: 14px 16px;
  display: flex;
  flex-direction: column;
  gap: 6px;
}

.chat-msg-user {
  align-self: flex-end;
  max-width: 85%;
  padding: 5px 10px;
  border-radius: 10px;
  background: var(--blue-tint);
  color: var(--ink);
  font-size: 11px;
  font-weight: 500;
  display: inline-flex;
  align-items: center;
  gap: 5px;
}
.chat-msg-user.active {
  background: var(--hi-yellow);
  color: #14181F;
}

.chat-msg-fold {
  padding: 4px 10px;
  border: 1px dashed var(--paper-line);
  border-radius: 8px;
  font-size: 10px;
  color: var(--ink-4);
  font-family: var(--f-mono);
  background: var(--paper);
}

.chat-msg-ai {
  display: flex;
  flex-direction: column;
  gap: 4px;
  padding: 8px 10px;
  background: var(--blue-soft);
  border-radius: 8px;
  border: 1px solid var(--blue-tint);
}
.ai-line {
  height: 5px;
  background: var(--paper-line);
  border-radius: 3px;
}

/* ── Sidebar card ── */
.sidebar-head {
  padding: 11px 13px;
  border-bottom: 1px solid var(--paper-line);
  background: var(--paper-2);
}
.sidebar-head-row {
  display: flex;
  align-items: center;
  gap: 8px;
  margin-bottom: 9px;
}
.sidebar-logo-mark {
  width: 20px; height: 20px;
  border-radius: 5px;
  background: var(--ink);
  color: var(--paper);
  display: grid;
  place-items: center;
  font-family: var(--f-display);
  font-style: italic;
  font-weight: 500;
  font-size: 12px;
  line-height: 1;
}
.sidebar-title-text {
  font-size: 12px;
  font-weight: 600;
  color: var(--ink);
  font-family: var(--f-sans);
}
.sidebar-count {
  font-family: var(--f-mono);
  font-size: 10px;
  padding: 1px 5px;
  background: var(--surface);
  border-radius: 3px;
  color: var(--ink-3);
  margin-left: auto;
}

.sidebar-filter {
  display: flex;
  align-items: center;
  gap: 6px;
  padding: 4px 8px;
  background: var(--surface);
  border: 1px solid var(--paper-line);
  border-radius: 6px;
}
.sidebar-filter-placeholder {
  font-size: 11px;
  color: var(--ink-4);
  flex: 1;
}
.sidebar-filter-kbd {
  font-family: var(--f-mono);
  font-size: 9px;
  padding: 1px 4px;
  background: var(--paper-2);
  border-radius: 3px;
  color: var(--ink-4);
}

.sidebar-list { padding: 7px 0; }
.sidebar-row {
  display: grid;
  grid-template-columns: 22px 1fr auto;
  gap: 5px;
  align-items: center;
  padding: 4px 13px;
  border-left: 2px solid transparent;
}
.sidebar-row.active {
  background: var(--blue-soft);
  border-left-color: var(--blue);
  padding-left: 11px;
}
.row-num {
  font-family: var(--f-mono);
  font-size: 9.5px;
  color: var(--ink-4);
}
.sidebar-row.active .row-num { color: var(--blue-deep); font-weight: 600; }
.row-text {
  font-size: 11px;
  color: var(--ink-2);
  overflow: hidden;
  text-overflow: ellipsis;
  white-space: nowrap;
}
.sidebar-row.active .row-text { color: var(--ink); font-weight: 600; }
.row-pin { font-size: 10px; }

.sidebar-foot {
  padding: 7px 13px;
  border-top: 1px solid var(--paper-line);
  background: var(--paper-2);
  font-size: 9px;
  color: var(--ink-4);
  font-family: var(--f-mono);
}

/* Audience marquee strip */
.hero-marquee {
  border-top: 1px solid var(--paper-line);
  padding: 16px 80px;
  display: flex;
  align-items: center;
  gap: 10px;
  flex-wrap: wrap;
  max-width: 100%;
}
.marquee-label {
  font-family: var(--f-mono);
  text-transform: uppercase;
  letter-spacing: 0.12em;
  font-size: 10px;
  color: var(--ink-3);
  white-space: nowrap;
}
.marquee-pill {
  padding: 4px 11px;
  border: 1px solid var(--paper-line);
  border-radius: 999px;
  font-size: 11.5px;
  color: var(--ink-2);
  background: var(--surface);
  white-space: nowrap;
}

/* ==================== COMPARISON SECTION ==================== */
#comparison {
  background: var(--paper);
}
#comparison .section-inner {
  max-width: var(--max-width);
  margin: 0 auto;
  padding: 88px 80px;
}

.comparison-header { margin-bottom: 56px; max-width: 720px; }

.comparison-grid {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: 28px;
}

.comparison-col-label {
  display: flex;
  align-items: center;
  gap: 10px;
  margin-bottom: 12px;
}
.col-dot {
  width: 8px; height: 8px;
  border-radius: 999px;
}
.col-label-text {
  font-family: var(--f-mono);
  font-size: 11px;
  letter-spacing: 0.1em;
  text-transform: uppercase;
  color: var(--ink-3);
}

/* "Without" card — messy chat */
.without-card {
  border-radius: 14px;
  height: 400px;
  background: var(--surface);
  border: 1px solid var(--paper-line);
  overflow: hidden;
  box-shadow: var(--sh-1);
  padding: 18px;
}

/* "With" card — folded chat + sidebar */
.with-card {
  border-radius: 14px;
  height: 400px;
  background: var(--surface);
  border: 1px solid var(--paper-line);
  overflow: hidden;
  box-shadow: var(--sh-2);
  display: grid;
  grid-template-columns: 1fr 170px;
}
.with-chat-side { padding: 18px; overflow: hidden; }
.with-sidebar-side {
  background: var(--paper-2);
  border-left: 1px solid var(--paper-line);
  padding: 12px;
}
.mini-sidebar-label {
  font-size: 9.5px;
  color: var(--ink-3);
  text-transform: uppercase;
  letter-spacing: 0.08em;
  font-family: var(--f-mono);
  margin-bottom: 9px;
}
.mini-sidebar-rows { display: flex; flex-direction: column; gap: 2px; }
.mini-row {
  display: flex;
  gap: 5px;
  padding: 3px 6px;
  border-radius: 4px;
  font-size: 10px;
  color: var(--ink-2);
  border-left: 2px solid transparent;
}
.mini-row.active {
  background: var(--blue-soft);
  color: var(--ink);
  font-weight: 600;
  border-left-color: var(--blue);
}
.mini-row-num {
  font-family: var(--f-mono);
  opacity: 0.6;
  font-size: 9px;
  flex-shrink: 0;
}
.mini-row-text { overflow: hidden; text-overflow: ellipsis; white-space: nowrap; }
.mini-row-pin { font-size: 9px; }

/* Boring chat lines */
.boring-chat { display: flex; flex-direction: column; gap: 5px; height: 100%; }
.boring-line { height: 6px; border-radius: 4px; }
.boring-user { background: var(--blue-tint); align-self: flex-end; }
.boring-ai   { background: var(--paper-2); }

/* Folded chat in comparison */
.folded-chat-list { display: flex; flex-direction: column; gap: 5px; }
.fcl-user {
  align-self: flex-end;
  max-width: 85%;
  padding: 4px 9px;
  border-radius: 8px;
  background: var(--blue-tint);
  color: var(--ink);
  font-size: 10.5px;
  font-weight: 500;
  display: inline-flex;
  align-items: center;
  gap: 5px;
}
.fcl-user.active { background: var(--hi-yellow); color: #14181F; }
.fcl-fold {
  padding: 3px 9px;
  border: 1px dashed var(--paper-line);
  border-radius: 6px;
  font-size: 9.5px;
  color: var(--ink-4);
  font-family: var(--f-mono);
}
.fcl-ai {
  display: flex;
  flex-direction: column;
  gap: 3px;
  padding: 6px 9px;
  background: var(--blue-soft);
  border-radius: 6px;
  border: 1px solid var(--blue-tint);
}
.fcl-ai-line { height: 4px; background: var(--paper-line); border-radius: 2px; }

.comparison-bullets {
  margin-top: 14px;
  padding: 0;
  list-style: none;
  display: flex;
  flex-direction: column;
  gap: 5px;
  font-size: 13px;
  color: var(--ink-3);
  font-family: var(--f-sans);
}

/* ==================== FEATURES SECTION ==================== */
#solution {
  background: var(--paper-2);
}

.features-header {
  margin-bottom: 64px;
  max-width: 720px;
}
.features-header-sub {
  font-size: 17px;
  line-height: 1.5;
  color: var(--ink-2);
  margin-top: 18px;
  max-width: 600px;
}

.feature-row {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: 80px;
  padding: 56px 0;
  border-top: 1px solid var(--paper-line);
  align-items: center;
}

.feature-text {}

.feature-num-row {
  display: flex;
  align-items: center;
  gap: 10px;
  margin-bottom: 18px;
}
.feature-num {
  font-family: var(--f-mono);
  font-size: 11px;
  color: var(--ink-4);
  letter-spacing: 0.1em;
}
.feature-divider {
  width: 24px;
  height: 1px;
  background: var(--paper-line);
}
.feature-kbd {
  display: inline-flex;
  align-items: center;
  padding: 3px 8px;
  background: var(--ink);
  color: var(--paper);
  border-radius: 5px;
  font-size: 11px;
  font-family: var(--f-mono);
  font-weight: 500;
}

.feature-h3 {
  font-family: var(--f-display);
  font-style: italic;
  font-weight: 400;
  font-size: 36px;
  line-height: 1.1;
  margin: 0 0 16px;
  letter-spacing: -0.015em;
  color: var(--ink);
}

.feature-body {
  font-size: 16px;
  line-height: 1.55;
  color: var(--ink-2);
  max-width: 440px;
}

/* Feature visuals */
.feature-visual {}

/* Fold visual */
.fold-visual {
  position: relative;
  height: 300px;
}
.fold-card-a,
.fold-card-b {
  position: absolute;
  width: 260px;
  padding: 14px;
  background: var(--surface);
  border-radius: 10px;
  border: 1px solid var(--paper-line);
}
.fold-card-a { top: 0; left: 0; transform: rotate(-1deg); box-shadow: var(--sh-1); }
.fold-card-b { top: 55px; right: 0; transform: rotate(2deg); box-shadow: var(--sh-2); }

.fold-user-msg {
  display: flex;
  justify-content: flex-end;
  margin-bottom: 8px;
}
.fold-user-bubble {
  background: var(--paper-2);
  padding: 5px 10px;
  border-radius: 10px;
  font-size: 11px;
  color: var(--ink-2);
}
.fold-user-bubble.blue {
  background: var(--blue);
  color: #fff;
}
.fold-ai-lines { display: flex; flex-direction: column; gap: 3px; }
.fold-ai-line { height: 5px; background: var(--paper-2); border-radius: 3px; }
.fold-pill {
  padding: 4px 10px;
  border: 1px dashed var(--paper-line);
  border-radius: 7px;
  font-size: 10px;
  color: var(--ink-4);
  font-family: var(--f-mono);
  display: flex;
  align-items: center;
  gap: 5px;
}

.fold-arrow-label {
  position: absolute;
  top: 120px;
  left: 80px;
  font-family: var(--f-display);
  font-style: italic;
  color: var(--blue);
  font-size: 28px;
  transform: rotate(-4deg);
}

/* Index visual — reuse sidebar card */
.index-visual {
  display: flex;
  justify-content: flex-end;
}

/* Folder visual */
.folder-visual {
  padding: 20px;
  background: var(--surface);
  border-radius: 12px;
  border: 1px solid var(--paper-line);
  box-shadow: var(--sh-2);
}
.folder-visual-label {
  font-size: 11px;
  color: var(--ink-3);
  font-family: var(--f-mono);
  text-transform: uppercase;
  letter-spacing: 0.08em;
  margin-bottom: 12px;
}
.folder-list { display: flex; flex-direction: column; gap: 8px; }
.folder-item {
  display: flex;
  align-items: center;
  gap: 10px;
  padding: 9px 11px;
  border-radius: 8px;
  background: var(--paper);
  border: 1px solid var(--paper-line);
}
.folder-icon { font-size: 14px; flex-shrink: 0; }
.folder-name { flex: 1; font-size: 13px; font-weight: 500; color: var(--ink); }
.folder-count {
  font-size: 11px;
  color: var(--ink-4);
  font-family: var(--f-mono);
}
.folder-dots { display: flex; gap: 2px; }
.folder-dot {
  width: 14px; height: 14px;
  border-radius: 4px;
  background: var(--paper-2);
  display: grid;
  place-items: center;
  font-size: 8px;
  color: var(--ink-4);
}

/* Filter visual */
.filter-visual {
  padding: 16px;
  background: var(--surface);
  border-radius: 12px;
  border: 1px solid var(--paper-line);
  box-shadow: var(--sh-2);
}
.filter-bar {
  display: flex;
  align-items: center;
  gap: 8px;
  padding: 7px 11px;
  background: var(--paper);
  border-radius: 8px;
  border: 1px solid var(--paper-line);
  margin-bottom: 10px;
}
.filter-query {
  font-size: 13px;
  color: var(--ink);
  font-weight: 500;
  flex: 1;
}
.filter-count {
  font-size: 10px;
  color: var(--ink-4);
  font-family: var(--f-mono);
}
.filter-results { display: flex; flex-direction: column; gap: 4px; }
.filter-result {
  display: flex;
  gap: 7px;
  padding: 5px 9px;
  background: var(--paper);
  border-radius: 6px;
  font-size: 11.5px;
  color: var(--ink);
}
.filter-result-num { font-family: var(--f-mono); color: var(--ink-4); font-size: 10px; flex-shrink: 0; }
.filter-highlight { background: var(--hi-yellow); padding: 0 2px; border-radius: 2px; }

.filter-footer {
  margin-top: 12px;
  padding-top: 10px;
  border-top: 1px dashed var(--paper-line);
  font-size: 11px;
  color: var(--ink-3);
  display: flex;
  align-items: center;
  gap: 8px;
}
.kbd-badge {
  font-family: var(--f-mono);
  font-size: 10px;
  padding: 2px 6px;
  background: var(--ink);
  color: var(--paper);
  border-radius: 4px;
}

/* ==================== USE CASES SECTION ==================== */
#use-cases {
  background: var(--paper-2);
}
#use-cases .section-inner {}

.usecases-header { margin-bottom: 56px; max-width: 720px; }

.usecases-grid {
  display: grid;
  grid-template-columns: repeat(3, 1fr);
  gap: 20px;
}

.usecase-card {
  background: var(--surface);
  border-radius: 14px;
  padding: 26px;
  border: 1px solid var(--paper-line);
  box-shadow: var(--sh-1);
  display: flex;
  flex-direction: column;
}

.usecase-avatar-row {
  display: flex;
  align-items: center;
  gap: 12px;
  margin-bottom: 20px;
}
.usecase-avatar {
  width: 40px; height: 40px;
  border-radius: 999px;
  display: grid;
  place-items: center;
  font-family: var(--f-display);
  font-style: italic;
  font-weight: 500;
  font-size: 15px;
  color: var(--ink);
  flex-shrink: 0;
}
.usecase-meta {}
.usecase-tag {
  font-family: var(--f-mono);
  font-size: 10px;
  letter-spacing: 0.08em;
  text-transform: uppercase;
  color: var(--ink-3);
  display: block;
  margin-bottom: 2px;
}
.usecase-who {
  font-size: 12.5px;
  color: var(--ink-2);
}

.usecase-h3 {
  font-family: var(--f-display);
  font-style: italic;
  font-weight: 400;
  font-size: 22px;
  line-height: 1.18;
  margin: 0 0 12px;
  letter-spacing: -0.01em;
  color: var(--ink);
}

.usecase-body {
  font-size: 14px;
  line-height: 1.55;
  color: var(--ink-2);
  flex: 1;
}

.usecase-footer {
  margin-top: 20px;
  padding-top: 16px;
  border-top: 1px dashed var(--paper-line);
  display: flex;
  align-items: center;
  gap: 8px;
  font-size: 11px;
  color: var(--ink-3);
  font-family: var(--f-mono);
}
.usecase-dot {
  width: 8px; height: 8px;
  border-radius: 999px;
  flex-shrink: 0;
}

/* ==================== HOW IT WORKS ==================== */
#how-it-works {
  background: var(--paper);
}
#how-it-works .section-inner { text-align: center; }

.hiw-header { margin-bottom: 64px; }

.steps-grid {
  display: grid;
  grid-template-columns: repeat(3, 1fr);
  gap: 0;
  margin-bottom: 56px;
  position: relative;
}
.steps-grid::after {
  content: '';
  position: absolute;
  top: 24px;
  left: calc(16.66% + 8px);
  width: calc(66.66% - 16px);
  height: 1px;
  background: var(--paper-line);
  z-index: 0;
}

.step {
  display: flex;
  flex-direction: column;
  align-items: center;
  gap: 14px;
  padding: 0 16px;
  position: relative;
  z-index: 1;
}

.step-number {
  width: 48px; height: 48px;
  border-radius: 50%;
  background: var(--ink);
  color: var(--paper);
  display: grid;
  place-items: center;
  font-family: var(--f-display);
  font-style: italic;
  font-size: 20px;
  font-weight: 400;
  border: 3px solid var(--paper);
  box-shadow: 0 0 0 1px var(--paper-line);
}

.step-label {
  font-family: var(--f-sans);
  font-size: 17px;
  font-weight: 600;
  color: var(--ink);
}
.step p {
  font-family: var(--f-sans);
  font-size: 14px;
  line-height: 1.5;
  color: var(--ink-3);
}

/* ==================== PRIVACY SECTION ==================== */
#privacy { background: var(--paper-2); }
#privacy .section-inner {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: 72px;
  align-items: center;
}

.privacy-left {}

#privacy h2 {
  font-family: var(--f-display);
  font-style: italic;
  font-weight: 400;
  font-size: 48px;
  line-height: 1.05;
  letter-spacing: -0.02em;
  color: var(--ink);
  margin-bottom: 18px;
}
.privacy-body {
  font-size: 16px;
  line-height: 1.55;
  color: var(--ink-2);
  margin-bottom: 28px;
}
.privacy-body p { margin-bottom: 8px; }
.privacy-link {
  font-size: 14px;
  color: var(--blue);
  border-bottom: 1px solid transparent;
  transition: border-color 0.18s;
}
.privacy-link:hover { border-color: var(--blue); }

.trust-list {
  background: var(--surface);
  border-radius: 14px;
  padding: 30px;
  border: 1px solid var(--paper-line);
  box-shadow: var(--sh-1);
  list-style: none;
  display: flex;
  flex-direction: column;
  gap: 16px;
}
.trust-list li {
  display: flex;
  align-items: center;
  gap: 14px;
  font-size: 15px;
  color: var(--ink-2);
}
.trust-check {
  width: 22px; height: 22px;
  border-radius: 50%;
  background: var(--blue);
  flex-shrink: 0;
  display: flex;
  align-items: center;
  justify-content: center;
}
.trust-check svg { width: 12px; height: 12px; }

/* ==================== FAQ SECTION ==================== */
#faq {
  background: var(--paper);
  border-top: 1px solid var(--paper-line);
}
#faq .section-inner { max-width: 720px; }

#faq h2 {
  font-family: var(--f-display);
  font-style: italic;
  font-weight: 400;
  font-size: 48px;
  line-height: 1.05;
  letter-spacing: -0.02em;
  color: var(--ink);
  margin-bottom: 44px;
  text-align: center;
}

.faq-list { display: flex; flex-direction: column; }
.faq-item { border-bottom: 1px solid var(--paper-line); }

.faq-question {
  width: 100%;
  background: none;
  border: none;
  padding: 20px 0;
  display: flex;
  justify-content: space-between;
  align-items: center;
  gap: 16px;
  cursor: pointer;
  text-align: left;
  font-family: var(--f-sans);
  font-size: 15px;
  font-weight: 500;
  line-height: 1.3;
  color: var(--ink);
  transition: color 0.18s;
}
.faq-question:hover { color: var(--blue); }

.faq-chevron {
  flex-shrink: 0;
  width: 18px; height: 18px;
  transition: transform 0.28s;
  color: var(--ink-4);
}
.faq-item.open .faq-chevron { transform: rotate(180deg); color: var(--blue); }

.faq-answer {
  max-height: 0;
  overflow: hidden;
  transition: max-height 0.32s ease;
}
.faq-item.open .faq-answer { max-height: 320px; }

.faq-answer p {
  font-size: 14px;
  line-height: 1.55;
  color: var(--ink-3);
  padding-bottom: 20px;
}

/* ==================== FINAL CTA ==================== */
#final-cta {
  background: var(--ink-2);
}
[data-theme="dark"] #final-cta {
  background: var(--paper-2);
}
#final-cta .section-inner { text-align: center; }

#final-cta h2 {
  font-family: var(--f-display);
  font-style: italic;
  font-weight: 400;
  font-size: 52px;
  line-height: 1.05;
  letter-spacing: -0.025em;
  color: var(--paper);
  margin-bottom: 14px;
}
[data-theme="dark"] #final-cta h2 { color: var(--ink); }

.final-sub {
  font-size: 18px;
  line-height: 1.5;
  color: rgba(250,248,244,0.72);
  margin-bottom: 40px;
}
[data-theme="dark"] .final-sub { color: var(--ink-2); }

#final-cta .cta-center {
  display: flex;
  flex-direction: column;
  align-items: center;
  gap: 14px;
}
#final-cta .cta-primary {
  background: var(--paper);
  color: var(--ink-2);
}
#final-cta .cta-primary:hover { opacity: 0.90; }
[data-theme="dark"] #final-cta .cta-primary {
  background: var(--ink);
  color: var(--paper);
}

.cta-note {
  font-size: 12px;
  color: rgba(250,248,244,0.48);
  font-family: var(--f-sans);
}
[data-theme="dark"] .cta-note { color: var(--ink-4); }

/* ==================== FOOTER ==================== */
footer {
  background: var(--ink);
  padding: 28px 5%;
}
.footer-inner {
  max-width: var(--max-width);
  margin: 0 auto;
  display: flex;
  justify-content: space-between;
  align-items: center;
  flex-wrap: wrap;
  gap: 14px;
}
.footer-links { display: flex; gap: 22px; list-style: none; flex-wrap: wrap; }
.footer-links a {
  font-size: 12px;
  color: rgba(250,248,244,0.44);
  transition: color 0.18s;
  font-family: var(--f-sans);
}
.footer-links a:hover { color: rgba(250,248,244,0.80); }
.footer-copy {
  font-size: 12px;
  color: rgba(250,248,244,0.26);
  font-family: var(--f-sans);
}

/* ==================== RESPONSIVE ==================== */
@media (max-width: 1100px) {
  .section-inner { padding: 72px 48px; }
  .hero-inner     { padding: 56px 48px 0; gap: 40px; }
  .hero-marquee   { padding: 14px 48px; }
  #comparison .section-inner { padding: 72px 48px; }
  .section-h2     { font-size: 46px; }
  .hero-h1        { font-size: 52px; }
}

@media (max-width: 900px) {
  .usecases-grid  { grid-template-columns: repeat(2, 1fr); }
  .comparison-grid { grid-template-columns: 1fr; gap: 24px; }
  .comparison-header .section-h2 { font-size: 40px; }
  .feature-row    { grid-template-columns: 1fr; gap: 40px; padding: 40px 0; }
  .feature-row.visual-left .feature-visual { order: -1; }
  .fold-visual    { height: 240px; }
  .filter-visual  { width: 100%; }
}

@media (max-width: 768px) {
  :root { --nav-height: 52px; }
  .nav-links   { display: none; }
  .lang-toggle { display: none; }
  .nav-hamburger { display: flex; }

  .hero-inner {
    grid-template-columns: 1fr;
    padding: 40px 24px 0;
    gap: 48px;
  }
  .hero-visuals { height: 380px; }
  .product-card-chat { width: 280px; }
  .product-card-sidebar { width: 200px; }
  .hero-h1     { font-size: 44px; }
  .hero-annot  { display: none; }
  .hero-marquee { padding: 12px 24px; }

  .section-inner  { padding: 56px 24px; }
  #comparison .section-inner { padding: 56px 24px; }

  .section-h2     { font-size: 36px; }
  #privacy h2     { font-size: 36px; }
  #faq h2         { font-size: 36px; }
  #final-cta h2   { font-size: 36px; }

  #privacy .section-inner { grid-template-columns: 1fr; gap: 36px; }

  .steps-grid  { grid-template-columns: 1fr; gap: 32px; }
  .steps-grid::after { display: none; }

  .usecases-grid  { grid-template-columns: 1fr; }
  .with-card { grid-template-columns: 1fr; }
  .with-sidebar-side { display: none; }
}

@media (max-width: 480px) {
  .hero-h1  { font-size: 36px; }
  .hero-sub { font-size: 16px; }
  .hero-visuals { height: 300px; }
  .product-card-chat    { width: 230px; }
  .product-card-sidebar { width: 170px; }
  .hero-card-front { right: -8px; }
  #final-cta h2 { font-size: 28px; }
  .cta-primary { font-size: 14px; padding: 11px 18px; }
}