:root {
    --bg: #16191b;
    --bg-deep: #0f1112;
    --panel: #1e2225;
    --panel-raised: #23282b;
    --border: #2a2f33;
    --text: #e7e9ea;
    --text-dim: #8b9296;
    --text-faint: #5b6266;
    --accent: #5eead4;
    --accent-dim: #2dd4bf26;
    --warn: #fbbf6b;
    --font-sans: -apple-system, "Segoe UI", Roboto, "Helvetica Neue", Arial, sans-serif;
    --font-mono: ui-monospace, "SF Mono", "JetBrains Mono", Consolas, monospace;
  }

  ::selection{
    background: #5eead4;
    color: #16191b;
  }

  * { box-sizing: border-box; }
  html { scroll-behavior: smooth; }

  body {
    margin: 0;
    background: var(--bg);
    color: var(--text);
    font-family: var(--font-sans);
    line-height: 1.5;
    -webkit-font-smoothing: antialiased;
  }

  a { color: inherit; }

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

  .wrap {
    max-width: 1080px;
    margin: 0 auto;
    padding: 0 24px;
  }

  p { max-width: 60ch; color: var(--text-dim); }

  /* ---------- Nav ---------- */

  header.nav {
    position: sticky;
    top: 0;
    z-index: 50;
    background: rgba(22, 25, 27, 0.88);
    backdrop-filter: blur(10px);
    border-bottom: 1px solid var(--border);
  }

  .nav-inner {
    display: flex;
    align-items: center;
    justify-content: space-between;
    height: 64px;
  }

  .logo {
    display: flex;
    align-items: center;
    gap: 10px;
    font-family: var(--font-mono);
    font-size: 15px;
    font-weight: 600;
    text-decoration: none;
    color: var(--text);
  }

  .logo-mark {
    display: flex;
    align-items: center;
    gap: 2px;
    height: 16px;
  }

  .logo-mark span {
    width: 2.5px;
    background: var(--accent);
    border-radius: 1px;
  }

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

  .nav-links a {
    text-decoration: none;
    color: var(--text-dim);
    font-size: 14px;
    transition: color 0.15s ease;
  }
  .nav-links a:hover { color: var(--text); }

  .nav-cta {
    display: flex;
    align-items: center;
    gap: 16px;
  }

  .btn {
    display: inline-flex;
    align-items: center;
    gap: 8px;
    border-radius: 8px;
    font-family: var(--font-sans);
    font-size: 14px;
    font-weight: 600;
    padding: 10px 18px;
    text-decoration: none;
    cursor: pointer;
    border: 1px solid transparent;
    transition: transform 0.12s ease, background 0.15s ease, border-color 0.15s ease;
  }
  .btn:active { transform: scale(0.98); }

  .btn-primary {
    background: var(--accent);
    color: #0b1413;
  }
  .btn-primary:hover { background: #7ff2df; }

  .btn-ghost {
    background: transparent;
    color: var(--text);
    border-color: var(--border);
  }
  .btn-ghost:hover { border-color: var(--text-faint); }

  .btn-disabled {
    background: transparent;
    color: var(--text-faint);
    border-color: var(--border);
    cursor: default;
  }
  .btn-disabled:hover { transform: none; }
  .btn:focus-visible, a:focus-visible, button:focus-visible {
    outline: 2px solid var(--accent);
    outline-offset: 2px;
  }

  .icon-github {
    width: 20px; height: 20px;
    color: var(--text-dim);
  }
  .icon-github:hover { color: var(--text); }

  .menu-toggle { display: none; }

  /* ---------- Hero ---------- */

  .hero {
    padding: 96px 0 72px;
    text-align: center;
  }

  .hero h1 {
    font-size: clamp(34px, 5vw, 54px);
    line-height: 1.12;
    letter-spacing: -0.01em;
    margin: 0 auto 20px;
    max-width: 15ch;
    font-weight: 700;
  }

  .hero p.lede {
    margin: 0 auto 36px;
    max-width: 52ch;
    font-size: 17px;
    color: var(--text-dim);
  }

  .hero-actions {
    display: flex;
    flex-direction: column;
    align-items: center;
    gap: 16px;
  }

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

  .btn-lg {
    font-size: 15px;
    padding: 13px 24px;
  }

  .platform-row {
    display: flex;
    align-items: center;
    gap: 18px;
    font-family: var(--font-mono);
    font-size: 12px;
    color: var(--text-faint);
  }

  .platform-row .pf {
    display: flex;
    align-items: center;
    gap: 6px;
  }
  .platform-row .pf.pf-active { color: var(--text-dim); }
  .platform-row .pf svg { width: 14px; height: 14px; }

  /* ---------- Waveform hero visual ---------- */

  .wave-stage {
    margin: 50px auto 0;
    display: flex;
    justify-content: center;
  }

  .wave-pill {
    display: flex;
    align-items: center;
    justify-content: center;
    gap: 4px;
    background: var(--panel);
    border: 1px solid var(--border);
    border-radius: 40px;
    padding: 28px 34px;
    height: 30px;
  }

  .wave-pill .bar {
    width: 4px;
    background: var(--accent);
    border-radius: 3px;
    transform: scaleY(0.2);
    animation: wave 1.6s ease-in-out infinite;
  }

  @keyframes wave {
    0%, 100% { transform: scaleY(0.2); opacity: 0.55; }
    50% { transform: scaleY(0.5); opacity: 0.80; }
  }

  @media (prefers-reduced-motion: reduce) {
    .wave-pill .bar { animation: none; transform: scaleY(0.4); }
  }

  /* ---------- How it works ---------- */

  section { padding: 88px 0; }
  section.alt { background: var(--bg-deep); border-top: 1px solid var(--border); border-bottom: 1px solid var(--border); }

  .section-head {
    max-width: 46ch;
    margin: 0 0 48px;
  }
  .section-head h2 {
    font-size: 30px;
    margin: 0 0 14px;
    letter-spacing: -0.01em;
  }

  .steps {
    display: grid;
    grid-template-columns: repeat(3, 1fr);
    gap: 32px;
  }

  .step {
    border-top: 1px solid var(--border);
    padding-top: 20px;
  }

  .step .num {
    font-family: var(--font-mono);
    color: var(--accent);
    font-size: 13px;
    margin-bottom: 12px;
  }

  .step h3 {
    font-size: 18px;
    margin: 0 0 8px;
  }

  .step p { font-size: 14.5px; margin: 0; max-width: 34ch; }

  /* ---------- Privacy block ---------- */

  .privacy-grid {
    display: grid;
    grid-template-columns: 1.1fr 0.9fr;
    gap: 56px;
    align-items: center;
  }

  .privacy-copy h2 { font-size: 28px; margin: 0 0 16px; letter-spacing: -0.01em; }
  .privacy-copy p { font-size: 15.5px; }

  .device-diagram {
    border: 1px dashed var(--border);
    border-radius: 14px;
    padding: 28px 20px;
    display: flex;
    flex-direction: column;
    align-items: center;
    gap: 16px;
    font-family: var(--font-mono);
    font-size: 13px;
  }

  .device-diagram .label-top {
    color: var(--text-faint);
    font-size: 11px;
  }

  .diagram-chip {
    background: var(--panel-raised);
    border: 1px solid var(--border);
    border-radius: 8px;
    padding: 10px 16px;
    color: var(--text);
    width: 100%;
    max-width: 220px;
    text-align: center;
  }

  .diagram-chip.accent { border-color: var(--accent); color: var(--accent); }

  .diagram-arrow { color: var(--text-faint); font-size: 16px; }

  /* ---------- Features ---------- */

  .feature-layout {
    display: grid;
    grid-template-columns: 1.2fr 1fr;
    gap: 40px;
  }

  .feature-lead {
    background: var(--panel);
    border: 1px solid var(--border);
    border-radius: 14px;
    padding: 32px;
  }

  .feature-lead h3 { font-size: 20px; margin: 0 0 10px; }
  .feature-lead p { font-size: 14.5px; margin: 0 0 20px; }

  .vocab-demo {
    display: flex;
    flex-wrap: wrap;
    gap: 8px;
  }

  .vocab-tag {
    font-family: var(--font-mono);
    font-size: 12.5px;
    background: var(--panel-raised);
    border: 1px solid var(--border);
    border-radius: 20px;
    padding: 6px 14px;
    color: var(--text-dim);
  }
  .vocab-tag.new { color: var(--accent); border-color: var(--accent); }

  .feature-list {
    display: flex;
    flex-direction: column;
    gap: 0;
  }

  .feature-item {
    border-top: 1px solid var(--border);
    padding: 20px 0;
  }
  .feature-item:last-child { border-bottom: 1px solid var(--border); }

  .feature-item h4 {
    font-size: 15.5px;
    margin: 0 0 6px;
  }
  .feature-item p { font-size: 14px; margin: 0; }

  /* ---------- Download ---------- */

  .download-panel {
    background: var(--panel);
    border: 1px solid var(--border);
    border-radius: 16px;
    padding: 56px 40px;
    text-align: center;
  }

  .download-panel h2 { font-size: 28px; margin: 0 0 12px; }
  .download-panel > p { margin: 0 auto 32px; }

  .platform-cards {
    display: grid;
    grid-template-columns: repeat(3, 1fr);
    gap: 16px;
    max-width: 640px;
    margin: 0 auto;
  }

  .platform-card {
    border: 1px solid var(--border);
    border-radius: 12px;
    padding: 22px 16px;
    background: var(--bg);
    display: flex;
    flex-direction: column;
    align-items: center;
    gap: 10px;
  }

  .platform-card.recommended {
    border-color: var(--accent);
    box-shadow: 0 0 0 1px var(--accent);
  }

  .platform-card svg { width: 26px; height: 26px; color: var(--text-dim); }
  .platform-card.recommended svg { color: var(--accent); }

  .platform-card .pname { font-size: 14px; font-weight: 600; }
  .platform-card .ptag {
    font-family: var(--font-mono);
    font-size: 11px;
    color: var(--text-faint);
  }
  .platform-card.recommended .ptag { color: var(--accent); }

  .platform-card a.btn { width: 100%; justify-content: center; margin-top: 4px; }

  /* ---------- FAQ ---------- */

  .faq-list { max-width: 720px; }

  .faq-item {
    border-top: 1px solid var(--border);
  }
  .faq-item:last-child { border-bottom: 1px solid var(--border); }

  .faq-item summary {
    list-style: none;
    cursor: pointer;
    padding: 22px 0;
    font-size: 16px;
    font-weight: 600;
    display: flex;
    justify-content: space-between;
    align-items: center;
    gap: 16px;
  }
  .faq-item summary::-webkit-details-marker { display: none; }

  .faq-item .chevron {
    flex-shrink: 0;
    width: 18px; height: 18px;
    color: var(--text-faint);
    transition: transform 0.2s ease;
  }
  .faq-item[open] .chevron { transform: rotate(180deg); }

  .faq-item .faq-answer {
    padding: 0 0 24px;
    font-size: 14.5px;
    max-width: 62ch;
  }

  /* ---------- Footer ---------- */

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

  .footer-inner {
    display: flex;
    align-items: center;
    justify-content: space-between;
    flex-wrap: wrap;
    gap: 16px;
  }

  .footer-links {
    display: flex;
    gap: 24px;
    font-size: 13.5px;
  }
  .footer-links a { color: var(--text-dim); text-decoration: none; }
  .footer-links a:hover { color: var(--text); }

  .footer-credit {
    font-family: var(--font-mono);
    font-size: 12px;
    color: var(--text-faint);
  }

  /* ---------- Responsive ---------- */

  @media (max-width: 860px) {
    .privacy-grid, .feature-layout { grid-template-columns: 1fr; }
    .device-diagram { max-width: 320px; margin: 0 auto; }
  }

  @media (max-width: 720px) {
    .nav-links { display: none; }
    .steps { grid-template-columns: 1fr; gap: 28px; }
    .platform-cards { grid-template-columns: 1fr; }
    section { padding: 64px 0; }
    .hero { padding: 64px 0 56px; }
    .download-panel { padding: 40px 22px; }
  }

  @media (max-width: 480px) {
    .wave-pill { padding: 20px 24px; height: 68px; gap: 3px; }
    .hero-buttons { flex-direction: column; width: 100%; }
    .hero-buttons .btn { width: 100%; justify-content: center; }
  }