/* ===================================================================
   Building Speech AI — landing page
   Palette: deep ink, warm spectrogram amber, electric cyan accent
   =================================================================== */

:root {
  --bg: #0a0d14;
  --bg-2: #0f1320;
  --bg-3: #141a2c;
  --surface: #161c2e;
  --surface-2: #1d2440;
  --line: rgba(255, 255, 255, 0.08);
  --line-strong: rgba(255, 255, 255, 0.16);
  --text: #e8ecf5;
  --text-dim: #a3acc4;
  --text-faint: #6f7a96;
  --accent: #ff9447;          /* spectrogram amber */
  --accent-2: #ffd166;        /* warm highlight */
  --accent-cool: #5ce1e6;     /* cyan — wave crest */
  --accent-deep: #b14df0;     /* purple — bass */
  --gradient-spectrum: linear-gradient(135deg, #b14df0 0%, #5ce1e6 35%, #ffd166 70%, #ff9447 100%);
  --shadow-1: 0 1px 3px rgba(0, 0, 0, 0.3), 0 8px 24px rgba(0, 0, 0, 0.25);
  --shadow-2: 0 4px 12px rgba(0, 0, 0, 0.35), 0 24px 64px rgba(0, 0, 0, 0.4);
  --radius-sm: 8px;
  --radius: 14px;
  --radius-lg: 22px;
  --max-w: 1200px;
  --serif: 'Fraunces', Georgia, 'Times New Roman', serif;
  --sans: 'Inter', system-ui, -apple-system, BlinkMacSystemFont, 'Segoe UI', sans-serif;
  --mono: 'JetBrains Mono', ui-monospace, 'SF Mono', Menlo, Consolas, monospace;
}

* { box-sizing: border-box; }

html { scroll-behavior: smooth; }

body {
  margin: 0;
  font-family: var(--sans);
  background: var(--bg);
  color: var(--text);
  line-height: 1.6;
  -webkit-font-smoothing: antialiased;
  -moz-osx-font-smoothing: grayscale;
  overflow-x: hidden;
}

a { color: inherit; }

::selection { background: var(--accent); color: #1a1108; }

.container {
  max-width: var(--max-w);
  margin: 0 auto;
  padding: 0 28px;
}

/* ===================================================================
   NAV
   =================================================================== */
.nav {
  position: fixed;
  top: 0;
  left: 0;
  right: 0;
  z-index: 100;
  background: rgba(10, 13, 20, 0.6);
  backdrop-filter: blur(16px) saturate(140%);
  -webkit-backdrop-filter: blur(16px) saturate(140%);
  border-bottom: 1px solid transparent;
  transition: border-color 0.3s ease, background 0.3s ease;
}
.nav.scrolled {
  border-bottom-color: var(--line);
  background: rgba(10, 13, 20, 0.85);
}
.nav-inner {
  max-width: var(--max-w);
  margin: 0 auto;
  padding: 14px 28px;
  display: flex;
  align-items: center;
  gap: 24px;
}
.nav-brand {
  display: inline-flex;
  align-items: center;
  gap: 10px;
  font-weight: 700;
  font-size: 15px;
  letter-spacing: -0.01em;
  text-decoration: none;
  color: var(--text);
}
.nav-brand svg { color: var(--accent); }
.nav-links {
  display: flex;
  gap: 28px;
  margin: 0 auto;
  padding: 0;
  list-style: none;
}
.nav-links a {
  text-decoration: none;
  color: var(--text-dim);
  font-size: 14px;
  font-weight: 500;
  transition: color 0.2s ease;
}
.nav-links a:hover { color: var(--text); }
.nav-cta {
  display: inline-flex;
  align-items: center;
  gap: 8px;
  padding: 9px 16px;
  border-radius: 999px;
  background: rgba(255, 255, 255, 0.04);
  border: 1px solid var(--line-strong);
  color: var(--text);
  text-decoration: none;
  font-size: 13px;
  font-weight: 600;
  transition: all 0.2s ease;
}
.nav-cta:hover {
  background: var(--accent);
  border-color: var(--accent);
  color: #1a1108;
}

@media (max-width: 800px) {
  .nav-links { display: none; }
}

/* ===================================================================
   HERO
   =================================================================== */
.hero {
  position: relative;
  min-height: 100vh;
  display: flex;
  align-items: center;
  justify-content: center;
  overflow: hidden;
  padding: 120px 28px 100px;
  background:
    radial-gradient(ellipse 80% 60% at 50% 0%, rgba(177, 77, 240, 0.18) 0%, transparent 60%),
    radial-gradient(ellipse 70% 50% at 100% 100%, rgba(255, 148, 71, 0.18) 0%, transparent 60%),
    radial-gradient(ellipse 60% 40% at 0% 80%, rgba(92, 225, 230, 0.12) 0%, transparent 60%),
    var(--bg);
}
#wave-canvas {
  position: absolute;
  inset: 0;
  width: 100%;
  height: 100%;
  z-index: 1;
  opacity: 0.55;
  pointer-events: none;
}
.hero-grid {
  position: absolute;
  inset: 0;
  background-image:
    linear-gradient(rgba(255, 255, 255, 0.03) 1px, transparent 1px),
    linear-gradient(90deg, rgba(255, 255, 255, 0.03) 1px, transparent 1px);
  background-size: 64px 64px;
  mask-image: radial-gradient(ellipse 60% 50% at 50% 50%, black 30%, transparent 75%);
  -webkit-mask-image: radial-gradient(ellipse 60% 50% at 50% 50%, black 30%, transparent 75%);
  z-index: 2;
}
.hero-content {
  position: relative;
  z-index: 3;
  text-align: center;
  max-width: 880px;
  width: 100%;
}
.badge {
  display: inline-flex;
  align-items: center;
  gap: 8px;
  padding: 6px 14px 6px 12px;
  background: rgba(255, 255, 255, 0.05);
  border: 1px solid var(--line-strong);
  border-radius: 999px;
  font-size: 12px;
  font-weight: 500;
  color: var(--text-dim);
  letter-spacing: 0.04em;
  margin-bottom: 32px;
}
.badge-release {
  background: linear-gradient(135deg, rgba(255, 148, 71, 0.18), rgba(255, 209, 102, 0.12));
  border-color: rgba(255, 148, 71, 0.45);
  color: var(--accent-2);
  font-weight: 600;
  letter-spacing: 0.06em;
  font-size: 12.5px;
  padding: 7px 16px 7px 13px;
  box-shadow: 0 0 24px -6px rgba(255, 148, 71, 0.45);
}
.badge-release .badge-dot {
  background: var(--accent);
  box-shadow: 0 0 10px var(--accent);
}
.badge-dot {
  width: 6px;
  height: 6px;
  border-radius: 50%;
  background: var(--accent-cool);
  box-shadow: 0 0 8px var(--accent-cool);
  animation: pulse 2s ease-in-out infinite;
}
@keyframes pulse {
  0%, 100% { opacity: 1; transform: scale(1); }
  50% { opacity: 0.6; transform: scale(0.9); }
}

.hero-title {
  font-family: var(--serif);
  font-weight: 900;
  font-size: clamp(56px, 11vw, 144px);
  line-height: 0.92;
  letter-spacing: -0.04em;
  margin: 0 0 28px;
}
.hero-title-pre {
  display: block;
  font-style: italic;
  font-weight: 500;
  color: var(--text-dim);
  font-size: 0.4em;
  margin-bottom: 4px;
  letter-spacing: 0.02em;
}
.hero-title-main {
  display: block;
  background: var(--gradient-spectrum);
  -webkit-background-clip: text;
  background-clip: text;
  -webkit-text-fill-color: transparent;
  filter: drop-shadow(0 0 30px rgba(255, 148, 71, 0.15));
}
.hero-title .accent { display: inline; }

.hero-sub {
  font-family: var(--serif);
  font-size: clamp(18px, 2.4vw, 26px);
  color: var(--text-dim);
  margin: 0 0 32px;
  line-height: 1.4;
  font-weight: 500;
}
.hero-sub em {
  font-style: italic;
  font-size: 0.92em;
  color: var(--text-faint);
}

.hero-lede {
  max-width: 680px;
  margin: 0 auto 48px;
  font-size: clamp(15px, 1.5vw, 17px);
  color: var(--text-dim);
  line-height: 1.7;
}

.hero-stats {
  display: flex;
  justify-content: center;
  gap: clamp(24px, 5vw, 64px);
  margin-bottom: 48px;
  flex-wrap: wrap;
}
.stat {
  text-align: center;
}
.stat-num {
  font-family: var(--serif);
  font-size: clamp(32px, 4vw, 44px);
  font-weight: 700;
  line-height: 1;
  background: linear-gradient(135deg, #ffd166, #ff9447);
  -webkit-background-clip: text;
  background-clip: text;
  -webkit-text-fill-color: transparent;
}
.stat-label {
  font-size: 12px;
  color: var(--text-faint);
  letter-spacing: 0.12em;
  text-transform: uppercase;
  margin-top: 6px;
}

.hero-cta {
  display: flex;
  gap: 14px;
  justify-content: center;
  flex-wrap: wrap;
}

.btn {
  display: inline-flex;
  align-items: center;
  gap: 10px;
  padding: 14px 26px;
  border-radius: 999px;
  font-size: 15px;
  font-weight: 600;
  text-decoration: none;
  cursor: pointer;
  border: 1px solid transparent;
  transition: all 0.25s cubic-bezier(0.4, 0, 0.2, 1);
  font-family: var(--sans);
  white-space: nowrap;
}
.btn.big { padding: 18px 34px; font-size: 16px; }
.btn-primary {
  background: var(--accent);
  color: #1a1108;
  box-shadow: 0 10px 30px -10px rgba(255, 148, 71, 0.6);
}
.btn-primary:hover {
  background: var(--accent-2);
  transform: translateY(-2px);
  box-shadow: 0 16px 40px -10px rgba(255, 148, 71, 0.8);
}
.btn-ghost {
  background: rgba(255, 255, 255, 0.04);
  border-color: var(--line-strong);
  color: var(--text);
}
.btn-ghost:hover {
  background: rgba(255, 255, 255, 0.08);
  border-color: rgba(255, 255, 255, 0.3);
  transform: translateY(-2px);
}

.hero-scroll {
  position: absolute;
  bottom: 32px;
  left: 50%;
  transform: translateX(-50%);
  z-index: 3;
  width: 24px;
  height: 38px;
  border: 2px solid rgba(255, 255, 255, 0.2);
  border-radius: 14px;
  display: flex;
  justify-content: center;
  padding-top: 6px;
}
.hero-scroll span {
  width: 3px;
  height: 8px;
  background: var(--accent-cool);
  border-radius: 2px;
  animation: scroll-down 1.8s ease-in-out infinite;
}
@keyframes scroll-down {
  0% { transform: translateY(0); opacity: 1; }
  60% { transform: translateY(14px); opacity: 0; }
  100% { transform: translateY(0); opacity: 0; }
}

/* ===================================================================
   GENERIC SECTIONS
   =================================================================== */
.section {
  padding: 120px 0;
  position: relative;
}
.section-head {
  max-width: 760px;
  margin: 0 auto 64px;
  text-align: center;
}
.eyebrow {
  display: inline-block;
  font-size: 12px;
  font-weight: 600;
  letter-spacing: 0.16em;
  text-transform: uppercase;
  color: var(--text-faint);
  margin-bottom: 16px;
  padding: 4px 12px;
  border-radius: 999px;
  border: 1px solid var(--line);
}
.accent-eyebrow {
  color: var(--accent);
  border-color: rgba(255, 148, 71, 0.3);
  background: rgba(255, 148, 71, 0.06);
}
.section h2 {
  font-family: var(--serif);
  font-weight: 700;
  font-size: clamp(30px, 4.4vw, 52px);
  line-height: 1.1;
  letter-spacing: -0.025em;
  margin: 0;
  color: var(--text);
}
.section-intro {
  margin: 24px auto 0;
  max-width: 640px;
  color: var(--text-dim);
  font-size: 17px;
  line-height: 1.7;
}

/* ===================================================================
   ABOUT
   =================================================================== */
.section-about {
  background: linear-gradient(180deg, transparent 0%, var(--bg-2) 100%);
}
.about-grid {
  display: grid;
  grid-template-columns: 1.4fr 1fr;
  gap: 64px;
  align-items: start;
}
.about-text { color: var(--text-dim); font-size: 16px; line-height: 1.75; }
.about-text .lede {
  font-size: 19px;
  color: var(--text);
  font-weight: 500;
  line-height: 1.6;
  margin-bottom: 24px;
}
.about-text p { margin: 0 0 22px; }
.quote {
  font-family: var(--serif);
  font-size: 24px;
  font-style: italic;
  color: var(--accent-2);
  line-height: 1.4;
  padding: 24px 28px;
  border-left: 3px solid var(--accent);
  background: rgba(255, 148, 71, 0.05);
  border-radius: 0 var(--radius) var(--radius) 0;
}
.quote-mark { color: var(--accent); font-size: 1.4em; vertical-align: -0.1em; }

.about-side { position: sticky; top: 100px; }
.card-spine {
  background:
    linear-gradient(180deg, rgba(255, 255, 255, 0.04) 0%, transparent 100%),
    linear-gradient(135deg, #1a1f33, #11141f);
  border: 1px solid var(--line-strong);
  border-radius: var(--radius);
  padding: 56px 32px;
  text-align: center;
  position: relative;
  overflow: hidden;
  margin-bottom: 24px;
  box-shadow: var(--shadow-2);
}
.card-spine::before {
  content: '';
  position: absolute;
  inset: 0;
  background: var(--gradient-spectrum);
  opacity: 0.06;
}
.card-spine::after {
  content: '';
  position: absolute;
  top: 0;
  left: 0;
  right: 0;
  height: 4px;
  background: var(--gradient-spectrum);
}
.spine-header {
  position: relative;
  z-index: 1;
  display: flex;
  flex-direction: column;
  gap: 10px;
}
.spine-header > span:first-child {
  font-size: 11px;
  letter-spacing: 0.32em;
  color: var(--text-faint);
  font-weight: 600;
}
.spine-title {
  font-family: var(--serif);
  font-size: 38px;
  font-weight: 700;
  line-height: 1.05;
  background: var(--gradient-spectrum);
  -webkit-background-clip: text;
  background-clip: text;
  -webkit-text-fill-color: transparent;
}
.spine-sub {
  font-family: var(--serif);
  font-style: italic;
  font-size: 14px;
  color: var(--text-dim);
}
.spine-author {
  margin-top: 16px;
  font-size: 13px;
  color: var(--text-faint);
  letter-spacing: 0.04em;
}

.bullet-list {
  list-style: none;
  padding: 0;
  margin: 0;
  border: 1px solid var(--line);
  border-radius: var(--radius);
  background: rgba(255, 255, 255, 0.02);
}
.bullet-list li {
  padding: 14px 18px;
  border-bottom: 1px solid var(--line);
  font-size: 14px;
  color: var(--text-dim);
}
.bullet-list li:last-child { border-bottom: none; }
.bullet-list strong { color: var(--text); font-weight: 600; }

@media (max-width: 900px) {
  .about-grid { grid-template-columns: 1fr; gap: 48px; }
  .about-side { position: static; }
}

/* ===================================================================
   ARC
   =================================================================== */
.section-arc { background: var(--bg-2); }
.arc-track {
  display: grid;
  grid-template-columns: repeat(4, 1fr);
  gap: 0;
  position: relative;
}
.arc-track::before {
  content: '';
  position: absolute;
  top: 36px;
  left: 5%;
  right: 5%;
  height: 1px;
  background: linear-gradient(90deg, transparent, var(--line-strong) 20%, var(--line-strong) 80%, transparent);
  z-index: 0;
}
.arc-step {
  position: relative;
  padding: 0 16px;
  text-align: center;
}
.arc-num {
  width: 72px;
  height: 72px;
  border-radius: 50%;
  background: var(--surface);
  border: 1px solid var(--line-strong);
  display: flex;
  align-items: center;
  justify-content: center;
  margin: 0 auto 20px;
  font-family: var(--serif);
  font-weight: 700;
  font-size: 24px;
  color: var(--accent-2);
  position: relative;
  z-index: 1;
  transition: all 0.3s ease;
}
.arc-step:hover .arc-num {
  background: var(--accent);
  color: #1a1108;
  border-color: var(--accent);
  transform: scale(1.08);
}
.arc-step h3 {
  font-family: var(--serif);
  font-size: 20px;
  margin: 0 0 12px;
  color: var(--text);
  font-weight: 600;
}
.arc-step p {
  font-size: 14px;
  color: var(--text-dim);
  margin: 0 0 16px;
  line-height: 1.6;
}
.arc-chip {
  display: inline-block;
  padding: 4px 12px;
  border-radius: 999px;
  font-size: 11px;
  font-weight: 600;
  letter-spacing: 0.08em;
  background: rgba(92, 225, 230, 0.08);
  color: var(--accent-cool);
  border: 1px solid rgba(92, 225, 230, 0.2);
  text-transform: uppercase;
}

@media (max-width: 800px) {
  .arc-track { grid-template-columns: 1fr 1fr; gap: 48px 16px; }
  .arc-track::before { display: none; }
}
@media (max-width: 480px) {
  .arc-track { grid-template-columns: 1fr; }
}

/* ===================================================================
   CHAPTERS
   =================================================================== */
.chapters-hint {
  text-align: center;
  font-size: 13px;
  color: var(--text-faint);
  margin: -32px 0 32px;
  letter-spacing: 0.02em;
}
.chapters-hint em { color: var(--accent-2); font-style: normal; }

.chapters-grid {
  display: grid;
  grid-template-columns: repeat(auto-fill, minmax(260px, 1fr));
  gap: 18px;
}

/* Each card is a 3D-flip container.
   Front: number/title/desc. Back (on hover or .flipped): watch-points + click-cue.
   Click anywhere on the card expands an inline sample below the row. */
.chapter-card {
  position: relative;
  perspective: 1400px;
  min-height: 175px;
  cursor: pointer;
  outline: none;
}
.ch-flipper {
  position: relative;
  width: 100%;
  height: 100%;
  min-height: 175px;
  transition: transform 0.7s cubic-bezier(0.4, 0, 0.2, 1);
  transform-style: preserve-3d;
}
.chapter-card:hover .ch-flipper,
.chapter-card:focus-visible .ch-flipper,
.chapter-card.flipped .ch-flipper {
  transform: rotateY(180deg);
}
.ch-face {
  position: absolute;
  inset: 0;
  padding: 18px 18px 14px;
  background: var(--surface);
  border: 1px solid var(--line);
  border-radius: var(--radius);
  backface-visibility: hidden;
  -webkit-backface-visibility: hidden;
  display: flex;
  flex-direction: column;
  overflow: hidden;
  transition: border-color 0.3s ease, box-shadow 0.3s ease;
}
.ch-face::before {
  content: '';
  position: absolute;
  top: 0;
  left: 0;
  right: 0;
  height: 2px;
  background: var(--gradient-spectrum);
  transform: scaleX(0);
  transform-origin: left;
  transition: transform 0.4s ease;
}
.chapter-card:hover .ch-face::before,
.chapter-card.flipped .ch-face::before { transform: scaleX(1); }
.chapter-card:hover .ch-face,
.chapter-card.flipped .ch-face {
  border-color: var(--line-strong);
  box-shadow: var(--shadow-2);
}

.ch-back {
  transform: rotateY(180deg);
  background: linear-gradient(155deg, rgba(255, 148, 71, 0.06) 0%, var(--surface) 80%);
  border-color: rgba(255, 148, 71, 0.25);
}

.chapter-card.highlight .ch-front {
  background: linear-gradient(135deg, rgba(255, 148, 71, 0.08), rgba(177, 77, 240, 0.06));
  border-color: rgba(255, 148, 71, 0.3);
}
.chapter-card.highlight .ch-face::before { transform: scaleX(1); }

.ch-num {
  font-family: var(--serif);
  font-size: 24px;
  font-weight: 700;
  color: var(--accent);
  line-height: 1;
  margin-bottom: 8px;
}
.chapter-card h3 {
  font-family: var(--serif);
  font-size: 17px;
  font-weight: 600;
  margin: 0 0 8px;
  color: var(--text);
  line-height: 1.25;
}
.chapter-card p {
  font-size: 13px;
  color: var(--text-dim);
  margin: 0;
  line-height: 1.5;
}
.ch-badge {
  display: inline-block;
  margin-top: auto;
  padding: 4px 10px;
  border-radius: 999px;
  font-size: 11px;
  font-weight: 700;
  letter-spacing: 0.08em;
  background: var(--accent);
  color: #1a1108;
  align-self: flex-start;
}

/* Back face content — denser to fit the smaller card */
.ch-back-label {
  font-size: 9px;
  font-weight: 700;
  letter-spacing: 0.18em;
  text-transform: uppercase;
  color: var(--accent);
  margin-bottom: 8px;
}
.ch-watch {
  list-style: none;
  padding: 0;
  margin: 0 0 10px;
  flex: 1;
}
.ch-watch li {
  position: relative;
  padding: 3px 0 3px 14px;
  font-size: 11.5px;
  color: var(--text-dim);
  line-height: 1.4;
}
.ch-watch li::before {
  content: '▸';
  position: absolute;
  left: 0;
  top: 3px;
  color: var(--accent);
  font-size: 10px;
}
.ch-watch li strong { color: var(--text); font-weight: 600; }
.ch-watch li em { color: var(--accent-2); font-style: italic; }
.ch-open-hint {
  display: block;
  font-size: 11px;
  color: var(--accent-2);
  font-weight: 600;
  letter-spacing: 0.02em;
  margin-top: auto;
  padding-top: 6px;
  border-top: 1px solid var(--line);
}

/* Touch devices: hover doesn't fire — show a small flip cue */
@media (hover: none) {
  .chapter-card::after {
    content: 'tap';
    position: absolute;
    bottom: 8px;
    right: 10px;
    font-size: 9px;
    letter-spacing: 0.16em;
    color: var(--text-faint);
    text-transform: uppercase;
    z-index: 2;
    pointer-events: none;
  }
}

/* ===================================================================
   INLINE CHAPTER EXPANSION
   Sits in the grid as a full-width row beneath the clicked card's row.
   =================================================================== */
.ch-expansion {
  grid-column: 1 / -1;
  position: relative;
  background: var(--surface-2);
  border: 1px solid var(--line-strong);
  border-radius: var(--radius-lg);
  overflow: hidden;
  margin: -2px 0 4px;
  animation: ch-expand-in 0.4s cubic-bezier(0.4, 0, 0.2, 1);
}
.ch-expansion::before {
  content: '';
  position: absolute;
  top: 0;
  left: 0;
  right: 0;
  height: 3px;
  background: var(--gradient-spectrum);
}
@keyframes ch-expand-in {
  from { opacity: 0; transform: translateY(-8px); max-height: 0; }
  to { opacity: 1; transform: translateY(0); max-height: 4000px; }
}

.ch-expansion-inner {
  padding: 32px 36px 28px;
  position: relative;
}

.ch-expansion-arrow {
  position: absolute;
  top: -10px;
  width: 18px;
  height: 18px;
  background: var(--surface-2);
  border-left: 1px solid var(--line-strong);
  border-top: 1px solid var(--line-strong);
  transform: rotate(45deg);
  transition: left 0.3s ease;
  z-index: 0;
}

.ch-expansion-close {
  position: absolute;
  top: 14px;
  right: 14px;
  width: 32px;
  height: 32px;
  border-radius: 8px;
  border: 1px solid var(--line);
  background: rgba(255, 255, 255, 0.04);
  color: var(--text-dim);
  cursor: pointer;
  display: flex;
  align-items: center;
  justify-content: center;
  transition: all 0.2s ease;
  z-index: 2;
}
.ch-expansion-close:hover {
  background: rgba(255, 255, 255, 0.1);
  color: var(--text);
  border-color: var(--line-strong);
}

.ch-expansion-meta {
  margin-bottom: 18px;
  padding-right: 44px;
}
.ch-expansion-eyebrow {
  display: inline-block;
  font-size: 11px;
  letter-spacing: 0.16em;
  text-transform: uppercase;
  color: var(--accent);
  font-weight: 700;
  margin-bottom: 6px;
}
.ch-expansion-title {
  font-family: var(--serif);
  font-size: clamp(22px, 2.6vw, 28px);
  font-weight: 700;
  line-height: 1.2;
  letter-spacing: -0.01em;
  margin: 0;
  color: var(--text);
}

.ch-expansion-body {
  color: var(--text-dim);
  font-size: 14.5px;
  line-height: 1.7;
}
.ch-expansion-body p { margin: 0 0 14px; }
.ch-expansion-body p:last-child { margin-bottom: 0; }
.ch-expansion-body h4 {
  font-family: var(--serif);
  font-size: 17px;
  font-weight: 600;
  color: var(--text);
  margin: 22px 0 8px;
  letter-spacing: -0.01em;
}
.ch-expansion-body strong { color: var(--text); font-weight: 600; }
.ch-expansion-body em { color: var(--accent-2); font-style: italic; }
.ch-expansion-body ul, .ch-expansion-body ol { margin: 0 0 14px; padding-left: 22px; }
.ch-expansion-body li { margin-bottom: 6px; }
.ch-expansion-body code {
  font-family: var(--mono);
  font-size: 0.85em;
  padding: 2px 6px;
  background: var(--bg);
  border: 1px solid var(--line);
  border-radius: 5px;
  color: var(--accent-2);
}
.ch-expansion-body pre {
  background: var(--bg);
  border: 1px solid var(--line);
  border-radius: 10px;
  padding: 14px 18px;
  font-family: var(--mono);
  font-size: 12.5px;
  line-height: 1.65;
  color: #d4dbef;
  overflow-x: auto;
  margin: 0 0 14px;
}
.ch-expansion-body pre code { padding: 0; background: none; border: none; color: inherit; }
.ch-expansion-body blockquote {
  margin: 0 0 14px;
  padding: 14px 20px;
  border-left: 3px solid var(--accent);
  background: rgba(255, 148, 71, 0.06);
  border-radius: 0 var(--radius) var(--radius) 0;
  font-family: var(--serif);
  font-size: 16px;
  font-style: italic;
  color: var(--accent-2);
  line-height: 1.5;
}
.ch-expansion-body table {
  width: 100%;
  border-collapse: collapse;
  margin: 0 0 14px;
  font-size: 13px;
}
.ch-expansion-body th, .ch-expansion-body td {
  text-align: left;
  padding: 8px 12px;
  border-bottom: 1px solid var(--line);
}
.ch-expansion-body th {
  color: var(--text);
  font-weight: 600;
  background: rgba(255, 255, 255, 0.02);
  font-size: 11.5px;
  letter-spacing: 0.06em;
  text-transform: uppercase;
}
.ch-expansion-body td code { white-space: nowrap; }
.ch-expansion-body .pull {
  display: block;
  margin: 12px 0 16px;
  padding: 12px 16px;
  border-radius: var(--radius);
  background: rgba(92, 225, 230, 0.06);
  border: 1px solid rgba(92, 225, 230, 0.2);
  font-size: 13.5px;
  color: var(--text);
}
.ch-expansion-body .pull strong { color: var(--accent-cool); }
.ch-expansion-body .timeline {
  list-style: none;
  padding: 0;
  margin: 0 0 14px;
  display: grid;
  gap: 2px;
  border-left: 2px solid var(--line-strong);
  padding-left: 14px;
}
.ch-expansion-body .timeline li { padding: 3px 0; font-size: 13px; }
.ch-expansion-body .timeline li b { color: var(--accent); font-family: var(--mono); margin-right: 10px; }

.ch-expansion-foot {
  display: flex;
  align-items: center;
  justify-content: space-between;
  margin-top: 22px;
  padding-top: 16px;
  border-top: 1px solid var(--line);
  gap: 12px;
}
.ch-expansion-nav {
  display: inline-flex;
  align-items: center;
  gap: 6px;
  padding: 7px 14px;
  border-radius: 8px;
  background: rgba(255, 255, 255, 0.04);
  border: 1px solid var(--line-strong);
  color: var(--text-dim);
  font-size: 12.5px;
  font-weight: 600;
  cursor: pointer;
  font-family: var(--sans);
  transition: all 0.2s ease;
}
.ch-expansion-nav:hover {
  background: rgba(255, 255, 255, 0.09);
  color: var(--text);
  border-color: rgba(255, 255, 255, 0.3);
}
.ch-expansion-nav:disabled {
  opacity: 0.35;
  cursor: not-allowed;
}
.ch-expansion-counter {
  font-size: 11px;
  color: var(--text-faint);
  letter-spacing: 0.08em;
  font-family: var(--mono);
}

/* Highlight the active card */
.chapter-card.active .ch-front,
.chapter-card.active .ch-back {
  border-color: var(--accent);
  box-shadow: 0 0 0 1px var(--accent), 0 12px 30px -10px rgba(255, 148, 71, 0.4);
}

@media (max-width: 600px) {
  .ch-expansion-inner { padding: 24px 20px 22px; }
  .ch-expansion-meta { padding-right: 36px; }
  .ch-expansion-arrow { display: none; }
}

/* ===================================================================
   CODE / NOTEBOOKS — the centerpiece
   =================================================================== */
.section-code {
  background:
    radial-gradient(ellipse 60% 40% at 50% 0%, rgba(255, 148, 71, 0.06) 0%, transparent 60%),
    var(--bg);
}

.code-toolbar {
  display: flex;
  align-items: center;
  gap: 10px;
  flex-wrap: wrap;
  margin-bottom: 32px;
  padding: 14px;
  background: var(--surface);
  border: 1px solid var(--line);
  border-radius: var(--radius);
}
.tool-btn {
  display: inline-flex;
  align-items: center;
  gap: 8px;
  padding: 8px 14px;
  border-radius: 8px;
  background: rgba(255, 255, 255, 0.03);
  border: 1px solid var(--line);
  color: var(--text-dim);
  text-decoration: none;
  font-size: 13px;
  font-weight: 500;
  transition: all 0.2s ease;
}
.tool-btn:hover {
  color: var(--text);
  background: rgba(255, 255, 255, 0.06);
  border-color: var(--line-strong);
}
.tool-spacer { flex: 1; min-width: 0; }

.filter-group {
  display: flex;
  gap: 4px;
  padding: 4px;
  background: var(--bg);
  border-radius: 10px;
  border: 1px solid var(--line);
}
.filter-btn {
  padding: 7px 14px;
  border: none;
  background: transparent;
  color: var(--text-faint);
  font-size: 12px;
  font-weight: 600;
  border-radius: 7px;
  cursor: pointer;
  font-family: var(--sans);
  letter-spacing: 0.02em;
  transition: all 0.2s ease;
}
.filter-btn:hover { color: var(--text); }
.filter-btn.active {
  background: var(--accent);
  color: #1a1108;
}

.notebook-grid {
  display: grid;
  grid-template-columns: repeat(auto-fill, minmax(330px, 1fr));
  gap: 20px;
}

.nb-card {
  position: relative;
  padding: 26px 24px 22px;
  background: var(--surface);
  border: 1px solid var(--line);
  border-radius: var(--radius);
  transition: all 0.3s cubic-bezier(0.4, 0, 0.2, 1);
  overflow: hidden;
  display: flex;
  flex-direction: column;
}
.nb-card::after {
  content: '';
  position: absolute;
  top: -1px;
  left: -1px;
  right: -1px;
  bottom: -1px;
  border-radius: var(--radius);
  background: var(--gradient-spectrum);
  opacity: 0;
  z-index: -1;
  transition: opacity 0.3s ease;
}
.nb-card:hover {
  transform: translateY(-6px);
  border-color: transparent;
  box-shadow: var(--shadow-2);
}
.nb-card:hover::after { opacity: 0.45; }
.nb-card.flagship {
  background: linear-gradient(155deg, rgba(255, 148, 71, 0.06) 0%, var(--surface) 60%);
  border-color: rgba(255, 148, 71, 0.25);
}

.nb-head {
  display: flex;
  align-items: center;
  gap: 10px;
  margin-bottom: 14px;
  flex-wrap: wrap;
}
.nb-num {
  font-family: var(--serif);
  font-size: 28px;
  font-weight: 800;
  line-height: 1;
  background: var(--gradient-spectrum);
  -webkit-background-clip: text;
  background-clip: text;
  -webkit-text-fill-color: transparent;
  margin-right: auto;
}
.nb-tag {
  font-size: 10px;
  font-weight: 700;
  letter-spacing: 0.08em;
  padding: 3px 8px;
  border-radius: 4px;
  text-transform: uppercase;
}
.tag-cpu { background: rgba(92, 225, 230, 0.12); color: var(--accent-cool); border: 1px solid rgba(92, 225, 230, 0.25); }
.tag-gpu-small { background: rgba(255, 209, 102, 0.12); color: var(--accent-2); border: 1px solid rgba(255, 209, 102, 0.25); }
.tag-gpu-large { background: rgba(255, 148, 71, 0.14); color: var(--accent); border: 1px solid rgba(255, 148, 71, 0.3); }
.tag-gpu-xl { background: rgba(177, 77, 240, 0.14); color: var(--accent-deep); border: 1px solid rgba(177, 77, 240, 0.3); }
.nb-flag {
  font-size: 9px;
  font-weight: 800;
  letter-spacing: 0.14em;
  padding: 3px 8px;
  border-radius: 4px;
  background: var(--accent-deep);
  color: #fff;
  text-transform: uppercase;
}
.nb-flag.warn { background: #d94343; }

.nb-card h3 {
  font-family: var(--serif);
  font-size: 22px;
  font-weight: 600;
  margin: 0 0 10px;
  letter-spacing: -0.01em;
  color: var(--text);
  line-height: 1.2;
}
.nb-card p {
  font-size: 14px;
  color: var(--text-dim);
  line-height: 1.6;
  margin: 0 0 18px;
  flex: 1;
}
.nb-tech {
  list-style: none;
  padding: 0;
  margin: 0 0 20px;
  display: flex;
  flex-wrap: wrap;
  gap: 6px;
}
.nb-tech li {
  font-family: var(--mono);
  font-size: 11px;
  padding: 3px 9px;
  background: rgba(255, 255, 255, 0.04);
  border: 1px solid var(--line);
  border-radius: 4px;
  color: var(--text-faint);
}

.nb-actions {
  display: flex;
  gap: 8px;
  flex-wrap: wrap;
}
.nb-btn {
  flex: 1;
  text-align: center;
  padding: 9px 12px;
  border-radius: 8px;
  font-size: 12.5px;
  font-weight: 600;
  text-decoration: none;
  border: 1px solid var(--line-strong);
  background: rgba(255, 255, 255, 0.03);
  color: var(--text-dim);
  transition: all 0.2s ease;
  white-space: nowrap;
}
.nb-btn:hover {
  background: rgba(255, 255, 255, 0.08);
  color: var(--text);
  border-color: rgba(255, 255, 255, 0.3);
}
.nb-btn.primary {
  background: var(--accent);
  border-color: var(--accent);
  color: #1a1108;
}
.nb-btn.primary:hover {
  background: var(--accent-2);
  border-color: var(--accent-2);
}
.nb-btn.ghost {
  background: transparent;
  border-style: dashed;
}

.nb-card[data-hidden="true"] { display: none; }

.code-cta {
  margin-top: 56px;
  text-align: center;
  padding: 32px;
  border: 1px dashed var(--line-strong);
  border-radius: var(--radius);
  background: rgba(255, 255, 255, 0.02);
}
.code-cta p {
  margin: 0 0 20px;
  color: var(--text-dim);
  font-size: 15px;
}

/* ===================================================================
   QUICK START
   =================================================================== */
.section-quickstart { background: var(--bg-2); }
.qs-grid {
  display: grid;
  grid-template-columns: repeat(2, 1fr);
  gap: 20px;
}
.qs-step {
  background: var(--surface);
  border: 1px solid var(--line);
  border-radius: var(--radius);
  padding: 24px;
  position: relative;
  transition: border-color 0.2s ease;
}
.qs-step:hover { border-color: var(--line-strong); }
.qs-step-wide { grid-column: 1 / -1; }
.qs-num {
  width: 32px;
  height: 32px;
  border-radius: 8px;
  background: linear-gradient(135deg, var(--accent), var(--accent-2));
  color: #1a1108;
  font-weight: 800;
  font-size: 15px;
  display: flex;
  align-items: center;
  justify-content: center;
  margin-bottom: 14px;
}
.qs-step h4 {
  font-size: 16px;
  margin: 0 0 16px;
  color: var(--text);
  font-weight: 600;
}
.code-block {
  margin: 0;
  background: var(--bg);
  border: 1px solid var(--line);
  border-radius: 10px;
  padding: 16px 18px;
  overflow-x: auto;
  font-family: var(--mono);
  font-size: 13px;
  line-height: 1.7;
  color: #d4dbef;
}
.code-block .cmt { color: var(--text-faint); font-style: italic; }

@media (max-width: 800px) {
  .qs-grid { grid-template-columns: 1fr; }
}

/* hardware block */
.hw-block {
  margin-top: 56px;
  padding: 32px;
  border: 1px solid var(--line);
  border-radius: var(--radius);
  background: var(--surface);
}
.hw-block h3 {
  font-family: var(--serif);
  font-size: 22px;
  margin: 0 0 20px;
  color: var(--text);
}
.hw-grid {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(220px, 1fr));
  gap: 14px;
  margin-bottom: 20px;
}
.hw-cell {
  display: flex;
  align-items: flex-start;
  gap: 12px;
  padding: 14px;
  background: var(--bg);
  border: 1px solid var(--line);
  border-radius: 10px;
}
.hw-tag {
  flex-shrink: 0;
  font-size: 10px;
  font-weight: 700;
  letter-spacing: 0.08em;
  padding: 4px 9px;
  border-radius: 4px;
  text-transform: uppercase;
  align-self: flex-start;
}
.hw-text {
  font-size: 13px;
  color: var(--text-dim);
  line-height: 1.5;
}
.hw-note {
  font-size: 13px;
  color: var(--text-faint);
  font-style: italic;
  margin: 0;
}

/* ===================================================================
   AUTHOR
   =================================================================== */
.section-author { background: var(--bg); }
.author-card {
  display: grid;
  grid-template-columns: 220px 1fr;
  gap: 48px;
  align-items: center;
  max-width: 900px;
  margin: 0 auto;
  padding: 40px;
  background: var(--surface);
  border: 1px solid var(--line);
  border-radius: var(--radius-lg);
  position: relative;
  overflow: hidden;
}
.author-card::before {
  content: '';
  position: absolute;
  top: 0;
  left: 0;
  width: 4px;
  height: 100%;
  background: var(--gradient-spectrum);
}
.author-photo-link {
  display: block;
  position: relative;
  width: 200px;
  height: 200px;
  margin: 0 auto;
  border-radius: 50%;
  text-decoration: none;
  cursor: pointer;
  isolation: isolate;
}
.author-photo {
  position: relative;
  z-index: 2;
  width: 100%;
  height: 100%;
  border-radius: 50%;
  object-fit: cover;
  display: block;
  border: 3px solid var(--bg);
  box-shadow: 0 12px 40px -10px rgba(0, 0, 0, 0.6);
  transition: transform 0.3s ease;
}
.author-photo-ring {
  position: absolute;
  inset: -6px;
  border-radius: 50%;
  background: var(--gradient-spectrum);
  z-index: 1;
  opacity: 0.85;
  transition: inset 0.3s ease, opacity 0.3s ease;
}
.author-photo-link:hover .author-photo { transform: scale(1.03); }
.author-photo-link:hover .author-photo-ring { inset: -10px; opacity: 1; }

.author-text h3 {
  font-family: var(--serif);
  font-size: 28px;
  font-weight: 700;
  margin: 0 0 4px;
  color: var(--text);
  line-height: 1.1;
}
.author-name-link {
  color: inherit;
  text-decoration: none;
  background-image: linear-gradient(transparent calc(100% - 1px), var(--accent) 0);
  background-repeat: no-repeat;
  background-size: 0% 100%;
  transition: background-size 0.35s ease, color 0.2s ease;
}
.author-name-link:hover {
  background-size: 100% 100%;
  color: var(--accent-2);
}
.author-role {
  font-size: 14px;
  color: var(--accent);
  margin: 0 0 18px;
  font-weight: 500;
  letter-spacing: 0.04em;
}
.author-text p {
  font-size: 15px;
  color: var(--text-dim);
  line-height: 1.7;
  margin: 0 0 16px;
}
.author-homepage-line {
  margin-top: 4px;
}
.author-homepage {
  display: inline-flex;
  align-items: center;
  gap: 6px;
  padding: 6px 12px;
  border-radius: 999px;
  background: rgba(255, 148, 71, 0.08);
  border: 1px solid rgba(255, 148, 71, 0.3);
  color: var(--accent-2);
  text-decoration: none;
  font-size: 13px;
  font-weight: 600;
  letter-spacing: 0.01em;
  transition: all 0.2s ease;
}
.author-homepage:hover {
  background: rgba(255, 148, 71, 0.18);
  border-color: var(--accent);
  color: var(--accent);
}
.author-homepage svg:last-child { opacity: 0.7; }

.author-links {
  display: flex;
  flex-wrap: wrap;
  gap: 8px;
  margin-top: 22px;
}
.author-link {
  display: inline-flex;
  align-items: center;
  gap: 7px;
  padding: 7px 13px;
  border-radius: 8px;
  background: rgba(255, 255, 255, 0.04);
  border: 1px solid var(--line-strong);
  color: var(--text-dim);
  text-decoration: none;
  font-size: 12.5px;
  font-weight: 500;
  transition: all 0.2s ease;
}
.author-link svg { flex-shrink: 0; }
.author-link:hover {
  background: rgba(255, 255, 255, 0.09);
  color: var(--text);
  border-color: rgba(255, 255, 255, 0.3);
  transform: translateY(-1px);
}

@media (max-width: 720px) {
  .author-card { grid-template-columns: 1fr; padding: 32px 24px; gap: 24px; text-align: center; }
  .author-text { text-align: left; }
  .author-links { justify-content: flex-start; }
}

/* ===================================================================
   FINAL CTA
   =================================================================== */
.section-final-cta {
  padding: 100px 0;
  background:
    radial-gradient(ellipse 60% 50% at 50% 50%, rgba(255, 148, 71, 0.1) 0%, transparent 70%),
    var(--bg-2);
}
.final-cta {
  text-align: center;
  max-width: 720px;
  margin: 0 auto;
}
.final-cta h2 {
  font-family: var(--serif);
  font-size: clamp(28px, 4vw, 44px);
  font-weight: 700;
  line-height: 1.2;
  letter-spacing: -0.02em;
  margin: 0 0 16px;
  background: var(--gradient-spectrum);
  -webkit-background-clip: text;
  background-clip: text;
  -webkit-text-fill-color: transparent;
}
.final-cta p {
  font-size: 17px;
  color: var(--text-dim);
  margin: 0 0 32px;
  line-height: 1.6;
}

/* ===================================================================
   FOOTER
   =================================================================== */
.footer {
  padding: 48px 0 60px;
  border-top: 1px solid var(--line);
  background: var(--bg);
}
.footer-inner {
  display: flex;
  justify-content: space-between;
  align-items: center;
  flex-wrap: wrap;
  gap: 24px;
}
.footer-title {
  font-family: var(--serif);
  font-weight: 700;
  font-size: 18px;
  color: var(--text);
}
.footer-sub {
  font-size: 13px;
  color: var(--text-faint);
  margin-top: 2px;
}
.footer-links {
  display: flex;
  gap: 20px;
  flex-wrap: wrap;
}
.footer-links a {
  font-size: 13px;
  color: var(--text-dim);
  text-decoration: none;
  transition: color 0.2s ease;
}
.footer-links a:hover { color: var(--accent); }
.footer-meta {
  font-size: 12px;
  color: var(--text-faint);
  letter-spacing: 0.04em;
}

/* ===================================================================
   SCROLL REVEAL
   =================================================================== */
/* Only hide for reveal when JS is present — no-JS users see everything */
.js .reveal {
  opacity: 0;
  transform: translateY(24px);
  transition: opacity 0.7s ease, transform 0.7s ease;
}
.js .reveal.in-view {
  opacity: 1;
  transform: translateY(0);
}

/* prefers-reduced-motion */
@media (prefers-reduced-motion: reduce) {
  *, *::before, *::after {
    animation-duration: 0.01ms !important;
    animation-iteration-count: 1 !important;
    transition-duration: 0.01ms !important;
  }
  .reveal { opacity: 1; transform: none; }
}

/* ===================================================================
   FEEDBACK PAGE — header, channels grid, form, thanks state
   =================================================================== */

/* nav active state */
.nav-links a.active {
  color: var(--accent);
}

.page-header {
  position: relative;
  padding: 140px 28px 70px;
  overflow: hidden;
  background:
    radial-gradient(ellipse 70% 50% at 50% 0%, rgba(177, 77, 240, 0.15) 0%, transparent 60%),
    radial-gradient(ellipse 60% 40% at 100% 100%, rgba(255, 148, 71, 0.14) 0%, transparent 60%),
    var(--bg);
  text-align: center;
}
.page-header-grid {
  position: absolute;
  inset: 0;
  background-image:
    linear-gradient(rgba(255, 255, 255, 0.03) 1px, transparent 1px),
    linear-gradient(90deg, rgba(255, 255, 255, 0.03) 1px, transparent 1px);
  background-size: 64px 64px;
  mask-image: radial-gradient(ellipse 60% 50% at 50% 50%, black 30%, transparent 75%);
  -webkit-mask-image: radial-gradient(ellipse 60% 50% at 50% 50%, black 30%, transparent 75%);
  z-index: 0;
}
.page-header > .container { position: relative; z-index: 1; }

.page-title {
  font-family: var(--serif);
  font-weight: 900;
  font-size: clamp(48px, 9vw, 96px);
  line-height: 0.95;
  letter-spacing: -0.03em;
  margin: 24px 0 20px;
}
.page-title-pre {
  display: block;
  font-style: italic;
  font-weight: 500;
  color: var(--text-dim);
  font-size: 0.4em;
  margin-bottom: 6px;
  letter-spacing: 0.02em;
}
.page-title-main {
  display: block;
  background: var(--gradient-spectrum);
  -webkit-background-clip: text;
  background-clip: text;
  -webkit-text-fill-color: transparent;
  filter: drop-shadow(0 0 30px rgba(255, 148, 71, 0.15));
}
.page-lede {
  max-width: 620px;
  margin: 0 auto;
  font-size: clamp(15px, 1.5vw, 17px);
  color: var(--text-dim);
  line-height: 1.7;
}

/* channels grid */
.section-feedback {
  padding: 80px 0 120px;
  background: linear-gradient(180deg, var(--bg) 0%, var(--bg-2) 100%);
}
.feedback-grid {
  display: grid;
  grid-template-columns: 1.5fr 1fr;
  grid-template-rows: auto auto;
  gap: 18px;
}
.feedback-card-primary {
  grid-column: 1;
  grid-row: 1 / 3;
}
.feedback-card-secondary { grid-column: 2; grid-row: 1; }
.feedback-card-tertiary  { grid-column: 2; grid-row: 2; }

@media (max-width: 880px) {
  .feedback-grid {
    grid-template-columns: 1fr;
    grid-template-rows: auto;
  }
  .feedback-card-primary, .feedback-card-secondary, .feedback-card-tertiary {
    grid-column: 1;
    grid-row: auto;
  }
}

.feedback-card {
  position: relative;
  padding: 32px;
  background: var(--surface);
  border: 1px solid var(--line);
  border-radius: var(--radius-lg);
  text-decoration: none;
  color: inherit;
  transition: all 0.25s cubic-bezier(0.4, 0, 0.2, 1);
  display: flex;
  flex-direction: column;
  overflow: hidden;
}
.feedback-card::before {
  content: '';
  position: absolute;
  top: 0;
  left: 0;
  right: 0;
  height: 3px;
  background: var(--gradient-spectrum);
  transform: scaleX(0);
  transform-origin: left;
  transition: transform 0.35s ease;
}
.feedback-card:hover { border-color: var(--line-strong); transform: translateY(-3px); box-shadow: var(--shadow-2); }
.feedback-card:hover::before { transform: scaleX(1); }
.feedback-card-primary::before { transform: scaleX(1); }

.feedback-card-head {
  display: flex;
  gap: 16px;
  align-items: flex-start;
  margin-bottom: 20px;
}
.feedback-icon {
  width: 44px;
  height: 44px;
  border-radius: 11px;
  background: rgba(255, 148, 71, 0.10);
  border: 1px solid rgba(255, 148, 71, 0.25);
  color: var(--accent);
  display: flex;
  align-items: center;
  justify-content: center;
  flex-shrink: 0;
}
.feedback-card h2 {
  font-family: var(--serif);
  font-size: 22px;
  font-weight: 700;
  margin: 0 0 4px;
  color: var(--text);
  letter-spacing: -0.01em;
}
.feedback-card-sub {
  font-size: 13px;
  color: var(--text-dim);
  margin: 0;
  line-height: 1.4;
}
.feedback-card-body {
  font-size: 14px;
  color: var(--text-dim);
  line-height: 1.6;
  margin: 0 0 18px;
  flex: 1;
}
.feedback-card-cta {
  display: inline-flex;
  align-items: center;
  gap: 7px;
  font-size: 13px;
  font-weight: 600;
  color: var(--accent);
  margin-top: auto;
}

/* form fields */
.feedback-form {
  display: flex;
  flex-direction: column;
  gap: 14px;
}
.form-row {
  display: flex;
  flex-direction: column;
  gap: 6px;
}
.form-label {
  font-size: 12px;
  font-weight: 600;
  color: var(--text);
  letter-spacing: 0.04em;
}
.form-optional {
  font-weight: 400;
  color: var(--text-faint);
  letter-spacing: 0;
}
.feedback-form input[type="email"],
.feedback-form input[type="text"],
.feedback-form select,
.feedback-form textarea {
  width: 100%;
  padding: 11px 14px;
  font-family: var(--sans);
  font-size: 14px;
  color: var(--text);
  background: var(--bg);
  border: 1px solid var(--line-strong);
  border-radius: 10px;
  outline: none;
  transition: border-color 0.2s ease, box-shadow 0.2s ease;
}
.feedback-form input:focus,
.feedback-form select:focus,
.feedback-form textarea:focus {
  border-color: var(--accent);
  box-shadow: 0 0 0 3px rgba(255, 148, 71, 0.15);
}
.feedback-form textarea {
  resize: vertical;
  line-height: 1.55;
  min-height: 130px;
}
.feedback-form select {
  appearance: none;
  -webkit-appearance: none;
  background-image: url("data:image/svg+xml;utf8,<svg xmlns='http://www.w3.org/2000/svg' viewBox='0 0 24 24' fill='none' stroke='%23a3acc4' stroke-width='2' stroke-linecap='round' stroke-linejoin='round'><polyline points='6 9 12 15 18 9'/></svg>");
  background-repeat: no-repeat;
  background-position: right 12px center;
  background-size: 16px;
  padding-right: 36px;
  cursor: pointer;
}
.feedback-form select option { background: var(--bg-2); color: var(--text); }

.form-honeypot {
  position: absolute;
  left: -9999px;
  width: 1px;
  height: 1px;
  overflow: hidden;
  opacity: 0;
}

.form-actions {
  display: flex;
  align-items: center;
  gap: 18px;
  margin-top: 8px;
  flex-wrap: wrap;
}
.form-submit {
  padding: 13px 26px;
  font-size: 14px;
}
.form-note {
  font-size: 12px;
  color: var(--text-faint);
  margin: 0;
  flex: 1;
  min-width: 200px;
  font-style: italic;
}

/* thank-you state */
.feedback-thanks {
  text-align: center;
  padding: 30px 0;
  animation: ch-modal-pop 0.4s cubic-bezier(0.4, 0, 0.2, 1);
}
.feedback-thanks-icon {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  width: 64px;
  height: 64px;
  border-radius: 50%;
  background: rgba(92, 225, 230, 0.12);
  border: 1px solid rgba(92, 225, 230, 0.3);
  color: var(--accent-cool);
  margin: 0 auto 18px;
}
.feedback-thanks h3 {
  font-family: var(--serif);
  font-size: 24px;
  font-weight: 700;
  margin: 0 0 8px;
  color: var(--text);
}
.feedback-thanks p {
  font-size: 15px;
  color: var(--text-dim);
  margin: 0 0 24px;
}

/* foot note */
.feedback-foot {
  text-align: center;
  max-width: 640px;
  margin: 56px auto 0;
  font-size: 14px;
  color: var(--text-dim);
  line-height: 1.7;
  font-style: italic;
}

/* =========================
   BUY SECTION
   ========================= */
.section-buy { background: var(--bg-2); }

.buy-grid {
  display: grid;
  grid-template-columns: repeat(3, 1fr);
  gap: 24px;
  margin-top: 48px;
}
@media (max-width: 900px) {
  .buy-grid { grid-template-columns: 1fr; }
}

.buy-card {
  background: var(--bg-3);
  border: 1px solid rgba(232, 236, 245, 0.08);
  border-radius: 16px;
  padding: 32px 28px;
  display: flex;
  flex-direction: column;
  position: relative;
  transition: transform 0.18s ease, border-color 0.18s ease;
}
.buy-card.available {
  border-color: rgba(255, 148, 71, 0.35);
  box-shadow: 0 0 0 1px rgba(255, 148, 71, 0.18), 0 12px 36px rgba(255, 148, 71, 0.08);
}
.buy-card:hover { transform: translateY(-3px); }
.buy-card.coming { opacity: 0.78; }

.buy-badge {
  display: inline-block;
  font-family: var(--mono);
  font-size: 11px;
  font-weight: 600;
  text-transform: uppercase;
  letter-spacing: 0.08em;
  padding: 4px 10px;
  border-radius: 4px;
  background: rgba(255, 148, 71, 0.16);
  color: var(--accent);
  margin-bottom: 18px;
  width: fit-content;
}
.buy-badge-preorder {
  background: rgba(92, 225, 230, 0.14);
  color: var(--accent-cool);
}
.buy-badge-coming {
  background: rgba(232, 236, 245, 0.08);
  color: var(--text-dim);
}

.buy-card h3 {
  font-family: var(--serif);
  font-size: 26px;
  font-weight: 700;
  margin: 0 0 8px;
  color: var(--text);
}

.buy-price {
  font-family: var(--mono);
  font-size: 32px;
  font-weight: 600;
  color: var(--accent-2);
  margin-bottom: 22px;
}

.buy-meta {
  list-style: none;
  padding: 0;
  margin: 0 0 26px;
  font-size: 14px;
  color: var(--text-dim);
  line-height: 1.85;
}
.buy-meta li::before {
  content: "→ ";
  color: var(--accent);
  font-weight: 600;
}

.buy-btn { margin-top: auto; text-align: center; justify-content: center; }
.buy-btn.disabled {
  opacity: 0.55;
  pointer-events: none;
  cursor: not-allowed;
}

.buy-note {
  text-align: center;
  margin-top: 36px;
  font-size: 14px;
  color: var(--text-dim);
  line-height: 1.7;
}
.buy-note-fine {
  display: block;
  margin-top: 6px;
  font-size: 12px;
  color: var(--text-faint);
}

/* =========================
   CITE SECTION
   ========================= */
.section-cite { background: var(--bg); }

.cite-grid {
  display: grid;
  grid-template-columns: repeat(3, 1fr);
  gap: 20px;
  margin-top: 40px;
}
@media (max-width: 900px) {
  .cite-grid { grid-template-columns: 1fr; }
}

.cite-card {
  background: var(--bg-2);
  border: 1px solid rgba(232, 236, 245, 0.08);
  border-radius: 12px;
  padding: 20px 22px;
}
.cite-card-wide {
  grid-column: 1 / -1;
}

.cite-label {
  font-family: var(--mono);
  font-size: 11px;
  font-weight: 600;
  letter-spacing: 0.1em;
  text-transform: uppercase;
  color: var(--accent-cool);
  margin-bottom: 12px;
}

.cite-block {
  background: rgba(0, 0, 0, 0.35);
  border-radius: 8px;
  padding: 14px 16px;
  margin: 0;
  overflow-x: auto;
  font-family: var(--mono);
  font-size: 12.5px;
  line-height: 1.65;
  color: var(--text);
  white-space: pre-wrap;
  word-break: break-word;
}
.cite-block em {
  color: var(--accent-2);
  font-style: italic;
}
.cite-card-wide .cite-block {
  white-space: pre;
  font-size: 12px;
}

.cite-note {
  text-align: center;
  margin-top: 32px;
  font-size: 13px;
  color: var(--text-dim);
  line-height: 1.75;
}
.cite-note code {
  font-family: var(--mono);
  font-size: 12px;
  background: rgba(232, 236, 245, 0.06);
  padding: 2px 6px;
  border-radius: 4px;
  color: var(--text);
}

/* =========================
   CHEATSHEET SECTION
   ========================= */
.section-cheatsheet { background: var(--bg-2); }

.cheatsheet-shell {
  margin-top: 40px;
  display: flex;
  flex-direction: column;
  align-items: center;
  gap: 20px;
}

.cheatsheet-image-link {
  display: block;
  max-width: 880px;
  width: 100%;
  position: relative;
  border-radius: 14px;
  overflow: hidden;
  border: 1px solid rgba(232, 236, 245, 0.1);
  box-shadow: 0 18px 64px rgba(0, 0, 0, 0.4), 0 4px 12px rgba(255, 148, 71, 0.08);
  transition: transform 0.22s ease, box-shadow 0.22s ease;
  background: #fffaf3;
}
.cheatsheet-image-link:hover {
  transform: translateY(-3px);
  box-shadow: 0 22px 80px rgba(0, 0, 0, 0.5), 0 6px 20px rgba(255, 148, 71, 0.18);
}
.cheatsheet-image {
  display: block;
  width: 100%;
  height: auto;
}
.cheatsheet-image-cta {
  position: absolute;
  top: 16px;
  right: 16px;
  display: inline-flex;
  align-items: center;
  gap: 6px;
  padding: 6px 12px;
  background: rgba(10, 13, 20, 0.85);
  color: var(--accent-2);
  border-radius: 6px;
  font-family: var(--mono);
  font-size: 11px;
  font-weight: 600;
  letter-spacing: 0.06em;
  text-transform: uppercase;
  backdrop-filter: blur(8px);
  opacity: 0;
  transition: opacity 0.22s ease;
}
.cheatsheet-image-link:hover .cheatsheet-image-cta { opacity: 1; }

.cheatsheet-cta-row {
  display: flex;
  flex-wrap: wrap;
  gap: 14px;
  justify-content: center;
  align-items: center;
  margin-top: 8px;
}
.cheatsheet-cta-row .btn-ghost {
  font-style: italic;
  font-size: 14px;
}

.cheatsheet-summary {
  margin-top: 56px;
}
.cheatsheet-summary h3 {
  font-family: var(--serif);
  font-size: 24px;
  font-weight: 700;
  text-align: center;
  margin-bottom: 28px;
  color: var(--text);
}

.cheatsheet-grid {
  display: grid;
  grid-template-columns: repeat(4, 1fr);
  gap: 18px;
}
@media (max-width: 1100px) {
  .cheatsheet-grid { grid-template-columns: repeat(2, 1fr); }
}
@media (max-width: 600px) {
  .cheatsheet-grid { grid-template-columns: 1fr; }
}

.cheatsheet-card {
  background: var(--bg-3);
  border: 1px solid rgba(232, 236, 245, 0.08);
  border-radius: 10px;
  padding: 20px;
}
.cheatsheet-card.highlight {
  border-color: rgba(255, 148, 71, 0.35);
  background: linear-gradient(180deg, var(--bg-3) 0%, rgba(255, 148, 71, 0.04) 100%);
}

.cs-label {
  font-family: var(--mono);
  font-size: 10px;
  font-weight: 600;
  letter-spacing: 0.12em;
  text-transform: uppercase;
  color: var(--accent);
  margin-bottom: 10px;
}
.cheatsheet-card h4 {
  font-family: var(--serif);
  font-size: 17px;
  font-weight: 700;
  color: var(--text);
  margin-bottom: 8px;
}
.cheatsheet-card p {
  font-size: 13px;
  color: var(--text-dim);
  line-height: 1.55;
}

.cheatsheet-more {
  margin-top: 36px;
  text-align: center;
  font-size: 14px;
  color: var(--text-dim);
}
.cheatsheet-more a {
  color: var(--accent-cool);
  text-decoration: none;
  margin: 0 4px;
}
.cheatsheet-more a:hover {
  color: var(--accent);
  text-decoration: underline;
}

/* =========================
   CHEATSHEET TABS (multi-infographic switcher)
   ========================= */
.cs-tabs {
  display: grid;
  grid-template-columns: repeat(3, 1fr);
  gap: 12px;
  margin: 40px auto 24px;
  max-width: 880px;
  background: var(--bg-3);
  border: 1px solid rgba(232, 236, 245, 0.08);
  border-radius: 14px;
  padding: 8px;
}
.cs-tab {
  display: flex;
  flex-direction: column;
  align-items: center;
  gap: 6px;
  padding: 14px 12px;
  background: transparent;
  border: none;
  border-radius: 10px;
  cursor: pointer;
  color: var(--text-dim);
  transition: background 0.18s ease, color 0.18s ease;
  font-family: inherit;
  font-size: 14px;
}
.cs-tab:hover {
  background: rgba(255, 148, 71, 0.06);
  color: var(--text);
}
.cs-tab.active {
  background: var(--accent);
  color: var(--ink);
}
.cs-tab-num {
  font-family: var(--mono);
  font-size: 11px;
  font-weight: 700;
  letter-spacing: 0.12em;
  opacity: 0.8;
}
.cs-tab-name {
  font-family: var(--serif);
  font-size: 17px;
  font-weight: 700;
  text-align: center;
  line-height: 1.2;
}

.cs-panel { display: none; }
.cs-panel.active { display: block; }

.cs-blurb {
  margin-top: 28px;
  text-align: center;
  font-size: 15px;
  color: var(--text-dim);
  line-height: 1.6;
  max-width: 880px;
  margin-left: auto;
  margin-right: auto;
}
.cs-blurb strong {
  color: var(--text);
  font-weight: 600;
}