:root {
  --bg: #07060b;
  --surface: rgba(255, 255, 255, 0.04);
  --surface-hover: rgba(255, 255, 255, 0.07);
  --border: rgba(255, 255, 255, 0.08);
  --text: #e4e2ec;
  --text-dim: #8b87a0;
  --accent: #7c5cfc;
  --accent2: #00d4ff;
  --accent3: #c850f2;
  --glow: rgba(124, 92, 252, 0.25);
  --radius: 16px;
  --font: "Inter", system-ui, -apple-system, BlinkMacSystemFont, sans-serif;
  --warn: #f87171;
  --warn-dim: rgba(248, 113, 113, 0.12);
}

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

html {
  scroll-behavior: smooth;
}

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

a {
  color: inherit;
}

:focus-visible {
  outline: 2px solid var(--accent2);
  outline-offset: 2px;
}

/* ── Canvas background ── */

#pulse-canvas {
  position: fixed;
  inset: 0;
  z-index: 0;
  pointer-events: none;
  opacity: 0.5;
}

/* ── Layout ── */

.container {
  max-width: 1100px;
  margin: 0 auto;
  padding: 0 24px;
  position: relative;
  z-index: 1;
}

section {
  padding: 100px 0;
}

/* ── Nav ── */

nav {
  position: fixed;
  top: 0;
  left: 0;
  right: 0;
  z-index: 100;
  padding: 16px 0;
  transition: background 0.3s, backdrop-filter 0.3s;
}

nav.scrolled {
  background: rgba(7, 6, 11, 0.85);
  backdrop-filter: blur(20px);
  border-bottom: 1px solid var(--border);
}

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

.logo {
  display: flex;
  align-items: center;
  gap: 10px;
  text-decoration: none;
  color: var(--text);
  font-weight: 700;
  font-size: 1.2rem;
}

.logo-icon {
  width: 32px;
  height: 32px;
  border-radius: 8px;
  background: linear-gradient(135deg, var(--accent), var(--accent3));
  display: flex;
  align-items: center;
  justify-content: center;
}

.logo-icon svg {
  width: 18px;
  height: 18px;
}

.nav-links {
  display: flex;
  gap: 32px;
  align-items: center;
}

.nav-links a {
  color: var(--text-dim);
  text-decoration: none;
  font-size: 0.9rem;
  font-weight: 500;
  transition: color 0.2s;
}

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

.nav-links .btn-sm {
  color: var(--bg);
  background: var(--text);
  padding: 8px 20px;
  border-radius: 999px;
  font-weight: 600;
  transition: transform 0.2s, box-shadow 0.2s;
}

.nav-links .btn-sm:hover {
  transform: translateY(-1px);
  box-shadow: 0 4px 20px rgba(255, 255, 255, 0.15);
}

.mobile-toggle {
  display: none;
  background: none;
  border: none;
  color: var(--text);
  cursor: pointer;
}

/* ── Hero ── */

.hero {
  min-height: 100vh;
  display: flex;
  align-items: center;
  padding: 120px 0 80px;
  position: relative;
}

.hero-content {
  max-width: 740px;
  margin: 0 auto;
  text-align: center;
}

.hero-badge {
  display: inline-flex;
  align-items: center;
  gap: 10px;
  padding: 6px 18px;
  border-radius: 999px;
  background: var(--surface);
  border: 1px solid var(--border);
  font-size: 0.82rem;
  color: var(--text-dim);
  margin-bottom: 36px;
  font-weight: 500;
}

.pulse-dot {
  width: 8px;
  height: 8px;
  border-radius: 50%;
  background: #34d399;
  flex-shrink: 0;
  animation: pulse 2s ease-in-out infinite;
}

@keyframes pulse {
  0%, 100% { opacity: 1; }
  50% { opacity: 0.35; }
}

.hero h1 {
  font-size: clamp(2.5rem, 6vw, 4.2rem);
  font-weight: 800;
  line-height: 1.08;
  letter-spacing: -0.03em;
  margin-bottom: 28px;
  background: linear-gradient(135deg, #fff 0%, var(--accent2) 45%, var(--accent3) 100%);
  background-size: 200% 200%;
  -webkit-background-clip: text;
  -webkit-text-fill-color: transparent;
  background-clip: text;
  animation: gradientShift 8s ease-in-out infinite;
}

@keyframes gradientShift {
  0%, 100% { background-position: 0% 50%; }
  50% { background-position: 100% 50%; }
}

.hero-sub {
  font-size: clamp(1.05rem, 2vw, 1.3rem);
  color: var(--text-dim);
  max-width: 580px;
  margin: 0 auto 44px;
  line-height: 1.7;
}

.hero-actions {
  display: flex;
  gap: 16px;
  justify-content: center;
  flex-wrap: wrap;
}

.btn {
  display: inline-flex;
  align-items: center;
  gap: 8px;
  padding: 14px 32px;
  border-radius: 999px;
  font-weight: 600;
  font-size: 1rem;
  text-decoration: none;
  transition: all 0.25s;
}

.btn-primary {
  background: linear-gradient(135deg, var(--accent), var(--accent3));
  color: #fff;
  box-shadow: 0 4px 30px var(--glow);
}

.btn-primary:hover {
  transform: translateY(-2px);
  box-shadow: 0 8px 40px var(--glow);
}

.btn-secondary {
  background: var(--surface);
  color: var(--text);
  border: 1px solid var(--border);
}

.btn-secondary:hover {
  background: var(--surface-hover);
  border-color: rgba(255, 255, 255, 0.15);
}

.hero-glow {
  position: absolute;
  top: 18%;
  left: 50%;
  transform: translateX(-50%);
  width: 650px;
  height: 650px;
  background: radial-gradient(circle, var(--glow) 0%, transparent 70%);
  pointer-events: none;
  z-index: -1;
}

.hero-content > * {
  animation: fadeUp 0.8s cubic-bezier(0.16, 1, 0.3, 1) both;
}

.hero-content > *:nth-child(1) { animation-delay: 0.1s; }
.hero-content > *:nth-child(2) { animation-delay: 0.2s; }
.hero-content > *:nth-child(3) { animation-delay: 0.35s; }
.hero-content > *:nth-child(4) { animation-delay: 0.5s; }

/* ── Section headers ── */

.section-header {
  text-align: center;
  margin-bottom: 64px;
}

.section-header .section-subtitle {
  margin: 0 auto;
}

.section-title {
  font-size: clamp(1.8rem, 4vw, 2.8rem);
  font-weight: 800;
  letter-spacing: -0.02em;
  margin-bottom: 16px;
}

.section-subtitle {
  color: var(--text-dim);
  font-size: 1.1rem;
  max-width: 540px;
  line-height: 1.7;
}

/* ── Install section ── */

.install-section {
  padding: 80px 0 100px;
}

.install-card {
  max-width: 640px;
  margin: 0 auto;
  background: var(--surface);
  border: 1px solid var(--border);
  border-radius: var(--radius);
  padding: 40px 36px;
  position: relative;
  overflow: hidden;
}

.install-card::before {
  content: "";
  position: absolute;
  top: 0;
  left: 0;
  right: 0;
  height: 2px;
  background: linear-gradient(90deg, var(--accent), var(--accent2));
}

.install-label {
  display: block;
  font-size: 0.82rem;
  font-weight: 600;
  text-transform: uppercase;
  letter-spacing: 0.08em;
  color: var(--text-dim);
  margin-bottom: 10px;
}

.install-url-row {
  display: flex;
  gap: 0;
  margin-bottom: 36px;
}

.install-url-input {
  flex: 1;
  background: var(--bg);
  border: 1px solid var(--border);
  border-right: none;
  border-radius: 10px 0 0 10px;
  padding: 14px 16px;
  color: var(--accent2);
  font-family: "JetBrains Mono", "SF Mono", "Fira Code", monospace;
  font-size: 0.88rem;
  outline: none;
  cursor: text;
  min-width: 0;
}

.install-url-input:focus {
  border-color: var(--accent);
}

.install-copy-btn {
  display: flex;
  align-items: center;
  justify-content: center;
  padding: 0 18px;
  background: var(--bg);
  border: 1px solid var(--border);
  border-left: 1px solid var(--border);
  border-radius: 0 10px 10px 0;
  color: var(--text-dim);
  cursor: pointer;
  transition: color 0.2s, background 0.2s;
}

.install-copy-btn:hover {
  color: var(--text);
  background: var(--surface-hover);
}

.install-copy-btn.copied {
  color: #34d399;
}

.install-steps h3 {
  font-size: 1.1rem;
  font-weight: 700;
  margin-bottom: 20px;
}

.install-ol {
  list-style: none;
  counter-reset: install-step;
  display: flex;
  flex-direction: column;
  gap: 20px;
}

.install-ol li {
  counter-increment: install-step;
  display: flex;
  gap: 16px;
  align-items: flex-start;
  font-size: 0.95rem;
  line-height: 1.65;
  color: var(--text-dim);
}

.install-ol li::before {
  content: counter(install-step);
  flex-shrink: 0;
  width: 28px;
  height: 28px;
  border-radius: 50%;
  display: flex;
  align-items: center;
  justify-content: center;
  font-weight: 700;
  font-size: 0.8rem;
  background: rgba(124, 92, 252, 0.12);
  color: var(--accent);
  border: 1px solid rgba(124, 92, 252, 0.25);
  margin-top: 1px;
}

.install-ol li strong {
  color: var(--text);
}

.install-ol li code {
  background: rgba(255, 255, 255, 0.06);
  padding: 2px 7px;
  border-radius: 5px;
  font-family: "JetBrains Mono", "SF Mono", "Fira Code", monospace;
  font-size: 0.85em;
  color: var(--accent2);
}

.install-ol li em {
  color: var(--text);
  font-style: normal;
}

.install-code {
  margin-top: 12px;
  background: var(--bg);
  border: 1px solid var(--border);
  border-radius: 10px;
  padding: 16px 20px;
  overflow-x: auto;
}

.install-code pre {
  font-family: "JetBrains Mono", "SF Mono", "Fira Code", monospace;
  font-size: 0.82rem;
  line-height: 1.7;
  color: var(--text-dim);
  margin: 0;
}

.install-code .key {
  color: var(--accent2);
}

.install-code .str {
  color: #a8db8a;
}

/* ── Karpathy quote ── */

.quote-section {
  padding: 60px 0 80px;
}

.quote-card {
  max-width: 720px;
  margin: 0 auto;
  text-align: center;
  padding: 52px 44px;
  background: linear-gradient(135deg, rgba(124, 92, 252, 0.06), rgba(0, 212, 255, 0.03));
  border: 1px solid rgba(124, 92, 252, 0.12);
  border-radius: 24px;
  position: relative;
}

.quote-mark {
  position: absolute;
  top: 24px;
  left: 32px;
  width: 36px;
  height: 36px;
  color: rgba(124, 92, 252, 0.15);
}

.quote-card p {
  font-size: clamp(1.1rem, 2.5vw, 1.35rem);
  font-style: italic;
  line-height: 1.75;
  color: var(--text);
  margin-bottom: 28px;
}

.quote-card footer {
  border: none;
  padding: 0;
}

.quote-card cite {
  font-style: normal;
}

.quote-card cite strong {
  display: block;
  color: var(--text);
  font-size: 1rem;
}

.quote-card cite span {
  display: block;
  color: var(--text-dim);
  font-size: 0.85rem;
  margin-top: 2px;
}

.quote-bridge {
  text-align: center;
  max-width: 540px;
  margin: 36px auto 0;
  font-size: 1.15rem;
  color: var(--text-dim);
  line-height: 1.75;
}

/* ── Problem cards ── */

.problem-section {
  padding: 80px 0 100px;
}

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

.problem-card {
  background: var(--surface);
  border: 1px solid var(--border);
  border-radius: var(--radius);
  padding: 36px 28px;
  transition: all 0.3s;
  position: relative;
  overflow: hidden;
}

.problem-card::before {
  content: "";
  position: absolute;
  top: 0;
  left: 0;
  right: 0;
  height: 2px;
  background: linear-gradient(90deg, var(--warn), #fbbf24);
  opacity: 0.5;
}

.problem-card:hover {
  background: var(--surface-hover);
  transform: translateY(-4px);
}

.problem-icon {
  width: 48px;
  height: 48px;
  border-radius: 12px;
  display: flex;
  align-items: center;
  justify-content: center;
  margin-bottom: 20px;
  background: var(--warn-dim);
  border: 1px solid rgba(248, 113, 113, 0.18);
}

.problem-icon svg {
  width: 24px;
  height: 24px;
  stroke: var(--warn);
}

.problem-card h3 {
  font-size: 1.15rem;
  font-weight: 700;
  margin-bottom: 10px;
}

.problem-card p {
  color: var(--text-dim);
  font-size: 0.92rem;
  line-height: 1.65;
}

/* ── Chat demo ── */

.demo-section {
  padding: 80px 0 100px;
}

.chat-window {
  max-width: 680px;
  margin: 0 auto;
  background: rgba(255, 255, 255, 0.025);
  border: 1px solid var(--border);
  border-radius: var(--radius);
  overflow: hidden;
}

.chat-header {
  display: flex;
  align-items: center;
  gap: 10px;
  padding: 14px 20px;
  border-bottom: 1px solid var(--border);
  background: rgba(255, 255, 255, 0.02);
  font-weight: 600;
  font-size: 0.9rem;
}

.chat-status {
  width: 8px;
  height: 8px;
  border-radius: 50%;
  background: #34d399;
  flex-shrink: 0;
}

.chat-messages {
  padding: 28px 24px;
  display: flex;
  flex-direction: column;
  gap: 18px;
}

.msg {
  display: flex;
  max-width: 88%;
}

.msg.user {
  align-self: flex-end;
}

.msg.ai {
  align-self: flex-start;
}

.msg-bubble {
  padding: 14px 18px;
  border-radius: 18px;
  font-size: 0.9rem;
  line-height: 1.65;
}

.msg.user .msg-bubble {
  background: linear-gradient(135deg, var(--accent), var(--accent3));
  color: #fff;
  border-bottom-right-radius: 6px;
}

.msg.ai .msg-bubble {
  background: var(--surface);
  border: 1px solid var(--border);
  color: var(--text);
  border-bottom-left-radius: 6px;
}

.briefing-topic {
  color: var(--accent2);
  font-weight: 600;
  font-size: 0.88rem;
  letter-spacing: 0.02em;
}

.chat-msg {
  opacity: 0;
  transform: translateY(18px);
  transition: opacity 0.5s cubic-bezier(0.16, 1, 0.3, 1),
              transform 0.5s cubic-bezier(0.16, 1, 0.3, 1);
}

.chat-msg.visible {
  opacity: 1;
  transform: translateY(0);
}

/* ── Steps (how it works) ── */

.steps {
  display: flex;
  flex-direction: column;
  gap: 0;
  position: relative;
  max-width: 640px;
  margin: 0 auto;
}

.steps::before {
  content: "";
  position: absolute;
  left: 24px;
  top: 24px;
  bottom: 24px;
  width: 2px;
  background: linear-gradient(180deg, var(--accent), var(--accent2), var(--accent3));
}

.step {
  display: flex;
  gap: 24px;
  align-items: flex-start;
  padding: 24px 0;
}

.step-number {
  flex-shrink: 0;
  width: 48px;
  height: 48px;
  border-radius: 50%;
  display: flex;
  align-items: center;
  justify-content: center;
  font-weight: 700;
  font-size: 1.1rem;
  background: var(--bg);
  border: 2px solid var(--accent);
  color: var(--accent);
  position: relative;
  z-index: 1;
}

.step:nth-child(2) .step-number {
  border-color: var(--accent2);
  color: var(--accent2);
}

.step:nth-child(3) .step-number {
  border-color: var(--accent3);
  color: var(--accent3);
}

.step-content h3 {
  font-size: 1.15rem;
  font-weight: 700;
  margin-bottom: 6px;
}

.step-content p {
  color: var(--text-dim);
  font-size: 0.95rem;
  line-height: 1.65;
}

/* ── CTA ── */

.cta {
  text-align: center;
  padding: 80px 0 120px;
}

.cta-box {
  background: linear-gradient(135deg, rgba(124, 92, 252, 0.12), rgba(200, 80, 242, 0.08));
  border: 1px solid rgba(124, 92, 252, 0.2);
  border-radius: 24px;
  padding: 64px 40px;
  position: relative;
  overflow: hidden;
}

.cta-box::before {
  content: "";
  position: absolute;
  inset: 0;
  background: radial-gradient(ellipse at 50% 0%, rgba(124, 92, 252, 0.15), transparent 70%);
  pointer-events: none;
}

.cta-box h2 {
  font-size: clamp(1.8rem, 4vw, 2.6rem);
  font-weight: 800;
  margin-bottom: 16px;
  letter-spacing: -0.02em;
}

.cta-box p {
  color: var(--text-dim);
  font-size: 1.1rem;
  margin-bottom: 36px;
  max-width: 480px;
  margin-left: auto;
  margin-right: auto;
  line-height: 1.7;
}

/* ── Footer ── */

footer {
  border-top: 1px solid var(--border);
  padding: 40px 0;
}

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

.footer-left {
  color: var(--text-dim);
  font-size: 0.85rem;
}

.footer-links {
  display: flex;
  gap: 24px;
}

.footer-links a {
  color: var(--text-dim);
  text-decoration: none;
  font-size: 0.85rem;
  transition: color 0.2s;
}

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

/* ── Animations ── */

@keyframes fadeUp {
  from {
    opacity: 0;
    transform: translateY(30px);
  }
  to {
    opacity: 1;
    transform: translateY(0);
  }
}

.fade-up {
  opacity: 0;
  transform: translateY(30px);
  transition: opacity 0.7s cubic-bezier(0.16, 1, 0.3, 1),
              transform 0.7s cubic-bezier(0.16, 1, 0.3, 1);
}

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

/* ── Responsive ── */

@media (max-width: 900px) {
  .problem-grid {
    grid-template-columns: repeat(2, 1fr);
  }
}

@media (max-width: 640px) {
  .problem-grid {
    grid-template-columns: 1fr;
  }

  .nav-links {
    display: none;
    position: fixed;
    top: 0;
    left: 0;
    right: 0;
    bottom: 0;
    background: rgba(7, 6, 11, 0.97);
    backdrop-filter: blur(20px);
    flex-direction: column;
    align-items: center;
    justify-content: center;
    gap: 32px;
    z-index: 99;
  }

  .nav-links.open {
    display: flex;
  }

  .nav-links a {
    font-size: 1.2rem;
  }

  .mobile-toggle {
    display: block;
    z-index: 101;
  }

  section {
    padding: 64px 0;
  }

  .quote-section {
    padding: 40px 0 64px;
  }

  .quote-card {
    padding: 36px 24px;
  }

  .quote-mark {
    display: none;
  }

  .chat-messages {
    padding: 20px 16px;
  }

  .msg {
    max-width: 94%;
  }

  .install-card {
    padding: 28px 20px;
  }

  .install-url-input {
    font-size: 0.78rem;
    padding: 12px 12px;
  }

  .install-code {
    padding: 12px 14px;
  }

  .install-code pre {
    font-size: 0.72rem;
  }

  .cta-box {
    padding: 48px 24px;
  }

  footer .container {
    flex-direction: column;
    gap: 12px;
    text-align: center;
  }
}

@media (prefers-reduced-motion: reduce) {
  html {
    scroll-behavior: auto;
  }

  *,
  *::before,
  *::after {
    animation: none !important;
    transition: none !important;
  }

  .fade-up,
  .chat-msg {
    opacity: 1;
    transform: none;
  }
}