/* ============ THEME TOKENS ============ */
  :root {
    /* LIGHT — the default (also the no-JS fallback) */
    --bg: #F4F6FA;
    --surface: #FFFFFF;
    --surface-2: #EAEEF6;
    --ink: #0D1220;
    --ink-dim: #454C5E;
    --muted: #7C8397;
    --line: rgba(13, 18, 32, 0.10);
    --line-2: rgba(13, 18, 32, 0.17);
    --accent: #2743E8;
    --accent-strong: #1B31C4;
    --accent-ink: #FFFFFF;
    --accent-soft: rgba(39, 67, 232, 0.09);
    --accent-line: rgba(39, 67, 232, 0.32);
    --dead: #9AA0AE;
    --dead-soft: rgba(154, 160, 174, 0.14);
    --shadow: 0 14px 38px -20px rgba(13, 18, 32, 0.38);
  }
  [data-theme="dark"] {
    /* DARK — strictly black & white, monochrome accent */
    --bg: #000000;
    --surface: #0C0C0D;
    --surface-2: #161618;
    --ink: #FFFFFF;
    --ink-dim: #B9B9BE;
    --muted: #7C7C83;
    --line: rgba(255, 255, 255, 0.14);
    --line-2: rgba(255, 255, 255, 0.24);
    --accent: #FFFFFF;
    --accent-strong: #FFFFFF;
    --accent-ink: #000000;
    --accent-soft: rgba(255, 255, 255, 0.10);
    --accent-line: rgba(255, 255, 255, 0.36);
    --dead: #6A6A70;
    --dead-soft: rgba(255, 255, 255, 0.05);
    --shadow: 0 14px 38px -20px rgba(0, 0, 0, 0.85);
  }

  :root {
    --sans: system-ui, -apple-system, "Segoe UI", Roboto, Helvetica, Arial, sans-serif;
    --mono: ui-monospace, "SF Mono", SFMono-Regular, Menlo, Consolas, monospace;
    --wrap: 1080px;
    --prose: 64ch;
  }

  * { box-sizing: border-box; }
  html { -webkit-text-size-adjust: 100%; }
  @media (prefers-reduced-motion: no-preference) { html { scroll-behavior: smooth; } }

  body {
    margin: 0;
    background: var(--bg);
    color: var(--ink);
    font-family: var(--sans);
    font-size: 1.0625rem;
    line-height: 1.62;
    -webkit-font-smoothing: antialiased;
    text-rendering: optimizeLegibility;
    overflow-x: hidden;
    transition: background-color .3s ease, color .3s ease;
  }
  ::selection { background: var(--accent); color: var(--accent-ink); }
  a { color: inherit; }
  img, svg, canvas { max-width: 100%; display: block; }
  h1, h2, h3 { margin: 0; text-wrap: balance; }
  p { margin: 0; }

  .wrap { width: 100%; max-width: var(--wrap); margin-inline: auto; padding-inline: clamp(1.15rem, 4vw, 2.25rem); }

  /* ============ TYPE UTILITIES ============ */
  .eyebrow {
    font-family: var(--mono); font-size: 0.72rem; letter-spacing: 0.18em;
    text-transform: uppercase; color: var(--accent); margin: 0; font-weight: 500;
  }
  .eyebrow.dim { color: var(--muted); }
  .lead { color: var(--ink-dim); font-size: clamp(1.05rem, 1.6vw, 1.24rem); line-height: 1.58; max-width: var(--prose); }
  .prose { max-width: var(--prose); }
  .prose p + p { margin-top: 1rem; }
  .num { font-variant-numeric: tabular-nums; }

  h2.h {
    font-weight: 720; font-size: clamp(1.8rem, 3.8vw, 2.85rem);
    line-height: 1.05; letter-spacing: -0.03em;
  }
  h3 { font-weight: 650; font-size: 1.075rem; letter-spacing: -0.015em; }

  a:focus-visible, button:focus-visible, summary:focus-visible, select:focus-visible {
    outline: 2px solid var(--accent); outline-offset: 3px; border-radius: 4px;
  }

  /* ============ HEADER ============ */
  header.top {
    position: sticky; top: 0; z-index: 40;
    background: color-mix(in srgb, var(--bg) 78%, transparent);
    backdrop-filter: blur(12px); -webkit-backdrop-filter: blur(12px);
    border-bottom: 1px solid var(--line);
  }
  .top-in { display: flex; align-items: center; gap: 1.25rem; height: 62px; }
  .brand { display: flex; align-items: center; gap: 0.6rem; text-decoration: none; }
  .brand .mast { width: 20px; height: 20px; color: var(--accent); flex: none; }
  .brand .mast svg { width: 20px; height: 20px; stroke: currentColor; fill: none; }
  .brand b { font-weight: 760; font-size: 1.3rem; letter-spacing: -0.03em; }
  .brand .sub { font-family: var(--mono); font-size: 0.64rem; letter-spacing: 0.1em; color: var(--muted); text-transform: uppercase; }
  @media (max-width: 560px) { .brand .sub { display: none; } }

  nav.links { margin-left: auto; display: flex; gap: 1.5rem; }
  nav.links a { font-size: 0.9rem; color: var(--ink-dim); text-decoration: none; }
  nav.links a:hover { color: var(--ink); }
  @media (max-width: 800px) { nav.links { display: none; } }

  .controls { margin-left: auto; display: flex; align-items: center; gap: 0.5rem; }
  nav.links + .controls { margin-left: 1.5rem; }
  .icon-btn {
    width: 38px; height: 38px; display: grid; place-items: center;
    border: 1px solid var(--line-2); border-radius: 10px; background: transparent;
    color: var(--ink); cursor: pointer; padding: 0;
  }
  .icon-btn:hover { background: var(--surface-2); }
  .icon-btn svg { width: 18px; height: 18px; stroke: currentColor; fill: none; stroke-width: 1.7; }
  .icon-btn .moon { display: none; }
  [data-theme="dark"] .icon-btn .sun { display: none; }
  [data-theme="dark"] .icon-btn .moon { display: block; }
  .lang-wrap { position: relative; display: flex; align-items: center; }
  .lang-select {
    appearance: none; -webkit-appearance: none;
    font-family: var(--mono); font-size: 0.76rem; letter-spacing: 0.06em; text-transform: uppercase;
    color: var(--ink); background: transparent; border: 1px solid var(--line-2);
    border-radius: 10px; padding: 0.5rem 1.8rem 0.5rem 0.7rem; cursor: pointer; height: 38px;
  }
  .lang-select:hover { background: var(--surface-2); }
  .lang-wrap::after {
    content: ""; position: absolute; right: 0.62rem; top: 50%; width: 7px; height: 7px;
    border-right: 1.6px solid var(--muted); border-bottom: 1.6px solid var(--muted);
    transform: translateY(-70%) rotate(45deg); pointer-events: none;
  }
  .lang-select option { color: initial; }

  /* ============ BADGES ============ */
  .badges { display: flex; flex-wrap: wrap; gap: 0.7rem; }
  .badge {
    display: inline-flex; align-items: center; gap: 0.6rem;
    padding: 0.6rem 1rem 0.64rem; background: var(--ink); color: var(--bg);
    border-radius: 12px; text-decoration: none; border: 1px solid transparent;
    transition: transform .15s ease, box-shadow .15s ease;
  }
  .badge:hover { transform: translateY(-2px); box-shadow: var(--shadow); }
  .badge svg { width: 22px; height: 22px; fill: var(--bg); flex: none; }
  .badge .bt { display: flex; flex-direction: column; line-height: 1.05; }
  .badge .bt small { font-size: 0.62rem; letter-spacing: 0.04em; text-transform: uppercase; opacity: 0.72; }
  .badge .bt span { font-size: 1.02rem; font-weight: 680; letter-spacing: -0.015em; }

  /* ============ SECTIONS ============ */
  section { border-top: 1px solid var(--line); }
  section.first { border-top: 0; }
  .pad { padding-block: clamp(3.6rem, 8vw, 6.5rem); }
  .kicker-row { display: flex; align-items: center; gap: 0.8rem; margin-bottom: 1.15rem; }
  .kicker-row .rule { height: 1px; background: var(--line-2); flex: 1; }

  /* ============ HERO ============ */
  .hero .pad { padding-top: clamp(2.8rem, 6vw, 4.6rem); padding-bottom: clamp(2.8rem, 6vw, 4.4rem); }
  .hero h1 {
    font-weight: 780; font-size: clamp(2.5rem, 6.6vw, 4.6rem);
    line-height: 0.99; letter-spacing: -0.045em; max-width: 15ch; margin-top: 1.1rem;
  }
  .hero h1 em { font-style: normal; color: var(--accent); }
  .hero .lead { margin-top: 1.4rem; }
  .hero .cta { margin-top: 2rem; }
  .hero .microtrust {
    margin-top: 1.2rem; display: flex; flex-wrap: wrap; gap: 0.5rem 1.3rem;
    font-family: var(--mono); font-size: 0.74rem; letter-spacing: 0.02em; color: var(--muted);
  }
  .hero .microtrust b { color: var(--ink-dim); font-weight: 500; display: inline-flex; align-items: center; gap: 0.4rem; }
  .hero .microtrust b::before { content: ""; width: 5px; height: 5px; border-radius: 50%; background: var(--accent); }
  .scope {
    background: var(--accent-soft); border: 1px solid var(--accent-line); color: var(--ink);
    border-radius: 14px; padding: 0.85rem 1.05rem; margin-top: 1.9rem; max-width: 48ch;
    font-size: 0.92rem; display: flex; gap: 0.7rem;
  }
  .scope svg { width: 18px; height: 18px; fill: var(--accent); margin-top: 0.15rem; flex: none; }
  .scope em { font-style: normal; font-family: var(--mono); font-size: 0.92em; }
  .wave-band { margin-top: 2.4rem; border-top: 1px solid var(--line); border-bottom: 1px solid var(--line); }
  .wave-band canvas { width: 100%; height: 92px; display: block; }

  /* ============ TIMELINE ============ */
  .timeline { display: grid; gap: 0; margin-top: 1.9rem; }
  .tl { display: grid; grid-template-columns: 9rem 1fr; gap: 1rem; padding: 0.9rem 0; border-top: 1px solid var(--line); align-items: baseline; }
  .tl:first-child { border-top: 0; }
  .tl .date { font-family: var(--mono); font-size: 0.82rem; color: var(--accent); letter-spacing: 0.01em; }
  .tl .date.past { color: var(--dead); }
  .tl .what b { display: block; font-weight: 650; }
  .tl .what span { color: var(--ink-dim); font-size: 0.94rem; }
  @media (max-width: 560px) { .tl { grid-template-columns: 1fr; gap: 0.15rem; } }

  /* ============ PATHS DIAGRAM ============ */
  .paths { display: grid; grid-template-columns: 1fr 1fr; gap: 1.15rem; margin-top: 2rem; }
  @media (max-width: 780px) { .paths { grid-template-columns: 1fr; } }
  .path { border: 1px solid var(--line-2); border-radius: 16px; padding: 1.4rem 1.35rem 1.55rem; background: var(--surface); position: relative; overflow: hidden; }
  .path.now { border-color: var(--accent-line); background: linear-gradient(180deg, var(--accent-soft), var(--surface)); }
  .path .tag { font-family: var(--mono); font-size: 0.7rem; letter-spacing: 0.14em; text-transform: uppercase; }
  .path.then .tag { color: var(--dead); }
  .path.now .tag { color: var(--accent); }
  .path h3 { margin-top: 0.5rem; margin-bottom: 1.1rem; }
  .diagram { display: flex; align-items: center; gap: 0.55rem; margin: 0.4rem 0 1.1rem; flex-wrap: wrap; }
  .node { display: flex; flex-direction: column; align-items: center; gap: 0.32rem; font-size: 0.66rem; font-family: var(--mono); letter-spacing: 0.03em; text-align: center; color: var(--ink-dim); }
  .node .ic { width: 44px; height: 44px; border-radius: 11px; display: grid; place-items: center; border: 1px solid var(--line-2); background: var(--surface-2); }
  .node .ic svg { width: 22px; height: 22px; fill: none; stroke-width: 1.7; }
  .then .node .ic svg { stroke: var(--dead); }
  .now .node .ic { border-color: var(--accent-line); background: var(--accent-soft); }
  .now .node .ic svg { stroke: var(--accent); }
  .link { flex: 1; min-width: 24px; height: 2px; position: relative; border-radius: 2px; }
  .then .link { background: repeating-linear-gradient(90deg, var(--dead) 0 6px, transparent 6px 12px); opacity: 0.7; }
  .now .link { background: var(--accent); }
  .link .x { position: absolute; top: 50%; left: 50%; transform: translate(-50%, -50%); width: 20px; height: 20px; border-radius: 50%; background: var(--surface); border: 1px solid var(--dead); color: var(--dead); display: grid; place-items: center; font-size: 0.68rem; font-family: var(--mono); }
  .path p { color: var(--ink-dim); font-size: 0.94rem; }
  .path .verdict { margin-top: 0.9rem; font-family: var(--mono); font-size: 0.78rem; letter-spacing: 0.01em; }
  .path.then .verdict { color: var(--dead); }
  .path.now .verdict { color: var(--accent); }
  .house-note { margin-top: 1.9rem; }
  .house-note em { font-style: normal; }

  /* ============ FEATURES ============ */
  .features { display: grid; grid-template-columns: repeat(3, 1fr); gap: 1rem; margin-top: 2rem; }
  @media (max-width: 820px) { .features { grid-template-columns: 1fr 1fr; } }
  @media (max-width: 520px) { .features { grid-template-columns: 1fr; } }
  .feat { border: 1px solid var(--line); border-radius: 14px; padding: 1.3rem 1.2rem; background: var(--surface); }
  .feat .fi { width: 30px; height: 30px; margin-bottom: 0.85rem; }
  .feat .fi svg { width: 30px; height: 30px; fill: none; stroke: var(--accent); stroke-width: 1.6; }
  .feat h3 { margin-bottom: 0.35rem; }
  .feat p { color: var(--ink-dim); font-size: 0.93rem; }
  .feat .tiny { display: block; margin-top: 0.55rem; font-family: var(--mono); font-size: 0.68rem; color: var(--muted); letter-spacing: 0.02em; }

  /* ============ STEPS ============ */
  .steps { display: grid; gap: 1rem; margin-top: 2rem; }
  .step { display: grid; grid-template-columns: 3.4rem 1fr; gap: 1.1rem; border: 1px solid var(--line); border-radius: 14px; padding: 1.25rem 1.3rem; background: var(--surface); }
  .step .no { font-family: var(--mono); font-size: 1.55rem; color: var(--accent); font-variant-numeric: tabular-nums; line-height: 1; font-weight: 500; }
  .step h3 { margin-bottom: 0.4rem; }
  .step p { color: var(--ink-dim); font-size: 0.96rem; }
  .step .hint { margin-top: 0.75rem; padding: 0.6rem 0.8rem; border-radius: 9px; background: var(--surface-2); border: 1px solid var(--line); font-size: 0.86rem; color: var(--ink-dim); }
  .step .hint b { color: var(--ink); }
  @media (max-width: 480px) { .step { grid-template-columns: 1fr; gap: 0.4rem; } }

  .troubleshoot { margin-top: 1.4rem; border: 1px dashed var(--line-2); border-radius: 13px; padding: 1.15rem 1.25rem; }
  .troubleshoot .eyebrow { margin-bottom: 0.7rem; }
  .troubleshoot ul { margin: 0; padding-left: 1.1rem; color: var(--ink-dim); font-size: 0.93rem; }
  .troubleshoot li { margin-bottom: 0.35rem; }
  .troubleshoot li b { color: var(--ink); }

  /* ============ COMPAT ============ */
  .compat-grid { display: grid; grid-template-columns: 1.3fr 1fr; gap: 1.15rem; margin-top: 2rem; }
  @media (max-width: 780px) { .compat-grid { grid-template-columns: 1fr; } }
  .panel { border: 1px solid var(--line); border-radius: 14px; padding: 1.3rem 1.35rem; background: var(--surface); }
  .panel h3 { margin-bottom: 0.9rem; }
  .models { display: flex; flex-wrap: wrap; gap: 0.5rem; }
  .chip { font-family: var(--mono); font-size: 0.78rem; letter-spacing: 0.01em; padding: 0.34rem 0.62rem; border-radius: 7px; border: 1px solid var(--line-2); color: var(--ink-dim); background: var(--surface-2); }
  .req { display: grid; gap: 0.7rem; }
  .req div { display: flex; justify-content: space-between; gap: 1rem; padding-bottom: 0.7rem; border-bottom: 1px solid var(--line); font-size: 0.92rem; }
  .req div:last-child { border-bottom: 0; padding-bottom: 0; }
  .req span { color: var(--muted); font-family: var(--mono); font-size: 0.74rem; letter-spacing: 0.03em; text-transform: uppercase; }
  .req b { text-align: right; }

  /* ============ CAN / CANNOT ============ */
  .cando { display: grid; grid-template-columns: 1fr 1fr; gap: 1.15rem; margin-top: 2rem; }
  @media (max-width: 640px) { .cando { grid-template-columns: 1fr; } }
  .cando ul { list-style: none; margin: 0.4rem 0 0; padding: 0; }
  .cando li { display: flex; gap: 0.65rem; padding: 0.55rem 0; border-top: 1px solid var(--line); font-size: 0.95rem; align-items: baseline; }
  .cando li:first-child { border-top: 0; }
  .cando .mk { font-family: var(--mono); flex: none; width: 1.1rem; }
  .can .mk { color: var(--accent); }
  .cant .mk { color: var(--dead); }
  .cant li { color: var(--ink-dim); }

  /* ============ FAQ ============ */
  .faq { margin-top: 2rem; border-top: 1px solid var(--line); }
  .faq details { border-bottom: 1px solid var(--line); }
  .faq summary { cursor: pointer; list-style: none; padding: 1.05rem 2.2rem 1.05rem 0; position: relative; font-weight: 620; font-size: 1.02rem; color: var(--ink); }
  .faq summary::-webkit-details-marker { display: none; }
  .faq summary::after { content: "+"; position: absolute; right: 0.2rem; top: 50%; transform: translateY(-50%); font-family: var(--mono); font-size: 1.3rem; color: var(--accent); }
  .faq details[open] summary::after { content: "\2212"; }
  .faq .ans { padding: 0 0 1.15rem; color: var(--ink-dim); font-size: 0.96rem; max-width: var(--prose); }
  .faq .ans a { color: var(--accent); }

  /* ============ FINAL ============ */
  .final { text-align: center; }
  .final h2 { margin-inline: auto; }
  .final .badges { justify-content: center; margin-top: 1.8rem; }
  .final .lead { margin-inline: auto; margin-top: 1rem; }

  /* ============ FOOTER ============ */
  footer { border-top: 1px solid var(--line-2); background: var(--surface); }
  .foot-grid { display: grid; grid-template-columns: 1.4fr 1fr 1fr; gap: 2rem; padding-block: clamp(2.6rem, 5vw, 3.6rem); }
  @media (max-width: 720px) { .foot-grid { grid-template-columns: 1fr; gap: 1.6rem; } }
  footer .brand b { font-size: 1.2rem; }
  footer h4 { font-family: var(--mono); font-size: 0.72rem; letter-spacing: 0.14em; text-transform: uppercase; color: var(--muted); margin: 0 0 0.9rem; }
  footer ul { list-style: none; margin: 0; padding: 0; display: grid; gap: 0.55rem; }
  footer ul a { color: var(--ink-dim); text-decoration: none; font-size: 0.92rem; }
  footer ul a:hover { color: var(--ink); }
  .legal { border-top: 1px solid var(--line); padding-block: 1.6rem 2.2rem; display: grid; gap: 1rem; }
  .legal .mark { font-family: var(--mono); font-size: 0.78rem; line-height: 1.6; color: var(--ink-dim); max-width: 78ch; }
  .legal .mark .req-en { color: var(--ink); }
  .legal .meta { font-size: 0.8rem; color: var(--muted); display: flex; flex-wrap: wrap; gap: 0.4rem 1.2rem; }
  .legal .meta b { color: var(--ink-dim); font-weight: 500; }
  .ph { color: var(--accent); font-family: var(--mono); font-size: 0.92em; }

  /* ============ REVEAL ============ */
  .reveal { opacity: 0; transform: translateY(14px); }
  .reveal.in { opacity: 1; transform: none; transition: opacity .6s ease, transform .6s ease; }
  @media (prefers-reduced-motion: reduce) { .reveal { opacity: 1; transform: none; } html { scroll-behavior: auto; } }

  /* ============ DOCUMENT / LEGAL PAGES ============ */
  .doc-main { padding-block: clamp(2.4rem, 6vw, 4.2rem); }
  .back-link { display: inline-flex; align-items: center; gap: 0.45rem; font-family: var(--mono); font-size: 0.74rem; letter-spacing: 0.08em; text-transform: uppercase; color: var(--muted); text-decoration: none; margin-bottom: 1.5rem; }
  .back-link:hover { color: var(--ink); }
  .back-link svg { width: 13px; height: 13px; stroke: currentColor; fill: none; stroke-width: 2; }
  .doc-head { margin-bottom: 2.2rem; }
  .doc-head h1 { font-weight: 760; font-size: clamp(2rem, 4.6vw, 3rem); letter-spacing: -0.035em; line-height: 1.03; }
  .doc-updated { margin-top: 0.7rem; font-family: var(--mono); font-size: 0.76rem; color: var(--muted); letter-spacing: 0.02em; }
  .doc { max-width: 68ch; }
  .doc > .intro { color: var(--ink); font-size: clamp(1.05rem, 1.6vw, 1.18rem); line-height: 1.55; margin-bottom: 1.6rem; }
  .doc h2 { font-weight: 700; font-size: 1.28rem; letter-spacing: -0.02em; margin: 2.3rem 0 0.7rem; }
  .doc h2:first-of-type { margin-top: 0.5rem; }
  .doc h3 { font-weight: 650; font-size: 1rem; margin: 1.5rem 0 0.4rem; }
  .doc p { color: var(--ink-dim); margin-bottom: 0.9rem; }
  .doc ul { color: var(--ink-dim); padding-left: 1.15rem; margin: 0 0 1rem; display: grid; gap: 0.55rem; }
  .doc a { color: var(--accent); }
  .doc .verbatim { color: var(--ink); font-weight: 500; }
  .notice { border: 1px solid var(--accent-line); background: var(--accent-soft); border-radius: 12px; padding: 0.9rem 1.1rem; font-size: 0.92rem; margin-bottom: 1.9rem; display: flex; gap: 0.6rem; color: var(--ink); max-width: 68ch; }
  .notice svg { width: 18px; height: 18px; fill: var(--accent); flex: none; margin-top: 0.12rem; }
  .dl { display: grid; gap: 0; margin: 0.4rem 0 1rem; }
  .dl div { display: flex; gap: 1rem; justify-content: space-between; border-bottom: 1px solid var(--line); padding: 0.55rem 0; font-size: 0.93rem; flex-wrap: wrap; }
  .dl div:last-child { border-bottom: 0; }
  .dl dt { color: var(--muted); font-family: var(--mono); font-size: 0.72rem; letter-spacing: 0.04em; text-transform: uppercase; margin: 0; }
  .dl dd { margin: 0; text-align: right; color: var(--ink); }
  .doc-links { display: flex; flex-wrap: wrap; gap: 0.7rem; margin-top: 0.5rem; }
  .doc-links a { display: inline-flex; align-items: center; gap: 0.45rem; padding: 0.55rem 0.95rem; border: 1px solid var(--line-2); border-radius: 10px; text-decoration: none; color: var(--ink); font-size: 0.88rem; }
  .doc-links a:hover { background: var(--surface-2); }
  .eula-body { max-width: 72ch; }
  .eula-body h2 { font-size: 1.08rem; margin-top: 1.9rem; }
  .eula-body p, .eula-body li { color: var(--ink-dim); font-size: 0.95rem; }
  .eula-body ol { color: var(--ink-dim); padding-left: 1.2rem; display: grid; gap: 0.4rem; margin: 0 0 1rem; }
  .eula-body .ph { color: var(--accent); }