:root {
    --bg: #11141a;
    --surface: #171b22;
    --surface-2: #1c212a;
    --border: #262b35;
    --text: #e9e8e4;
    --text-muted: #8b92a0;
    --text-dim: #565d6b;
    --brass: #b08d57;
    --brass-dim: #8a6f45;
    --signal: #6b93b5;
    --serif: 'Spectral', Georgia, serif;
    --sans: 'IBM Plex Sans', -apple-system, BlinkMacSystemFont, sans-serif;
  }

  /* Light mode is opt-in only, per message, never remembered — no localStorage,
     no prefers-color-scheme. Reload and it's dark again. */
  html[data-theme="light"] {
    --bg: #f6f4ef;
    --surface: #ffffff;
    --surface-2: #eeebe3;
    --border: #ddd7c9;
    --text: #201d19;
    --text-muted: #5b5548;
    --text-dim: #8a8375;
    --brass: #9c7a3f;
    --brass-dim: #b08d57;
    --signal: #3d6a8f;
  }

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

  html { scroll-behavior: smooth; }

  body {
    background: var(--bg);
    color: var(--text);
    font-family: var(--sans);
    line-height: 1.6;
    -webkit-font-smoothing: antialiased;
  }

  a { color: inherit; }

  .wrap {
    max-width: 1080px;
    margin: 0 auto;
    padding: 0 32px;
  }

  /* ---------- Nav ---------- */
  header {
    padding: 28px 0;
    border-bottom: 1px solid var(--border);
  }
  header .wrap {
    display: flex;
    justify-content: space-between;
    align-items: center;
  }
  .mark {
    font-family: var(--serif);
    font-size: 19px;
    font-weight: 600;
    letter-spacing: 0.01em;
  }
  .mark span { color: var(--brass); }
  /* THE BOLT WORDMARK, PAINTED THROUGH THE PNG'S ALPHA RATHER THAN FROM ITS OWN
     PIXELS — and that is the whole reason it works in both themes from one file.
     The artwork is a single near-white (#F1EFE9) on transparent: correct on the
     dark theme, and all but invisible on the light one, whose background is
     #f6f4ef — five points apart. A mask takes only the SHAPE and takes the
     colour from a token, so the light theme gets a dark mark for free and there
     is no second, hand-recoloured file that can drift out of step with this one.
     --text rather than --brass so dark mode still resolves to very nearly the
     artwork's own colour; swap the one line to make it the accent.
     -webkit- first for Safari, which still needs the prefix. */
  .mark-img {
    display: block;
    width: 160px; height: 48px;
    background: var(--text);
    -webkit-mask: url('/img/zerowitness-mark.png') no-repeat center / contain;
    mask: url('/img/zerowitness-mark.png') no-repeat center / contain;
  }
  nav a {
    text-decoration: none;
    color: var(--text-muted);
    font-size: 14.5px;
    margin-left: 32px;
    transition: color 0.2s ease;
  }
  nav a:hover { color: var(--text); }
  .theme-switch {
    display: inline-flex;
    align-items: center;
    gap: 6px;
    background: none;
    border: none;
    padding: 0;
    cursor: pointer;
    margin-left: 24px;
    line-height: 0;
  }
  .theme-icon {
    color: var(--text-dim);
    transition: color 0.2s ease;
  }
  .theme-switch[aria-checked="true"] .theme-icon-sun { color: var(--brass); }
  .theme-switch:not([aria-checked="true"]) .theme-icon-moon { color: var(--brass); }
  .theme-switch-track {
    display: inline-flex;
    align-items: center;
    width: 42px;
    height: 24px;
    background: var(--surface-2);
    border: 1px solid var(--border);
    border-radius: 999px;
    padding: 2px;
    transition: border-color 0.2s ease;
  }
  .theme-switch:hover .theme-switch-track { border-color: var(--text-dim); }
  .theme-switch-thumb {
    width: 18px;
    height: 18px;
    border-radius: 50%;
    background: var(--brass);
    transform: translateX(0);
    transition: transform 0.2s ease;
  }
  .theme-switch[aria-checked="true"] .theme-switch-thumb { transform: translateX(18px); }

  /* ---------- Hero ---------- */
  .hero {
    padding: 120px 0 100px;
    border-bottom: 1px solid var(--border);
  }
  .hero-grid {
    display: grid;
    grid-template-columns: 1.15fr 0.85fr;
    gap: 64px;
    align-items: center;
  }
  h1 {
    font-family: var(--serif);
    font-weight: 500;
    font-size: 46px;
    line-height: 1.22;
    max-width: 620px;
    letter-spacing: -0.01em;
  }
  .lede {
    margin-top: 26px;
    font-size: 17px;
    color: var(--text-muted);
    max-width: 480px;
    line-height: 1.7;
  }
  .cta-row {
    margin-top: 38px;
    display: flex;
    align-items: center;
    gap: 22px;
  }
  .btn {
    display: inline-block;
    background: var(--brass);
    color: #14161b;
    font-weight: 600;
    font-size: 15px;
    padding: 13px 26px;
    border-radius: 3px;
    text-decoration: none;
    white-space: nowrap;
    transition: background 0.2s ease;
  }
  .btn:hover { background: #c39b62; }
  .cta-note {
    font-size: 13.5px;
    color: var(--text-dim);
  }

  /* erasure demo */
  .demo {
    background: var(--surface);
    border: 1px solid var(--border);
    border-radius: 4px;
    padding: 28px;
    min-height: 220px;
    display: flex;
    flex-direction: column;
    justify-content: center;
  }
  .demo-label {
    font-size: 12.5px;
    color: var(--text-dim);
    margin-bottom: 16px;
  }
  .demo-line {
    font-family: var(--serif);
    font-size: 18px;
    color: var(--text);
    min-height: 54px;
  }
  .demo-cursor {
    display: inline-block;
    width: 2px;
    height: 18px;
    background: var(--signal);
    margin-left: 2px;
    vertical-align: -2px;
    animation: blink 1s step-end infinite;
  }
  @keyframes blink { 50% { opacity: 0; } }
  .demo-footer {
    margin-top: 18px;
    font-size: 12.5px;
    color: var(--text-dim);
    border-top: 1px solid var(--border);
    padding-top: 14px;
  }

  /* ---------- How it works ---------- */
  .section {
    padding: 96px 0;
    border-bottom: 1px solid var(--border);
  }
  .section-head {
    font-family: var(--serif);
    font-size: 30px;
    font-weight: 500;
    max-width: 480px;
    margin-bottom: 56px;
  }
  .steps {
    display: grid;
    grid-template-columns: repeat(3, 1fr);
    gap: 44px;
  }
  .step-num {
    font-family: var(--serif);
    font-size: 15px;
    color: var(--brass);
    margin-bottom: 14px;
  }
  .step h3 {
    font-size: 17px;
    font-weight: 600;
    margin-bottom: 10px;
  }
  .step p {
    font-size: 14.5px;
    color: var(--text-muted);
    line-height: 1.65;
  }

  /* ---------- Why section ---------- */
  .why {
    padding: 96px 0;
    border-bottom: 1px solid var(--border);
  }
  .why-grid {
    display: grid;
    grid-template-columns: 0.9fr 1.1fr;
    gap: 64px;
  }
  .why-grid h2 {
    font-family: var(--serif);
    font-size: 28px;
    font-weight: 500;
    line-height: 1.3;
  }
  .why-body p {
    color: var(--text-muted);
    font-size: 15.5px;
    line-height: 1.75;
    max-width: 540px;
  }
  .why-body p + p { margin-top: 18px; }
  .why-body strong { color: var(--text); font-weight: 600; }

  .honest-note {
    margin-top: 32px;
    padding: 18px 20px;
    background: var(--surface);
    border-left: 2px solid var(--brass-dim);
    font-size: 14px;
    color: var(--text-muted);
    max-width: 540px;
  }

  /* ---------- FAQ ---------- */
  .faq {
    padding: 96px 0;
    border-bottom: 1px solid var(--border);
  }
  .faq h2 {
    font-family: var(--serif);
    font-size: 30px;
    font-weight: 500;
    margin-bottom: 48px;
  }

  /* Mode comparison, moved here from the chat page — it was an accordion inside
     the mode bar, which spent permanent vertical space on the one screen where
     space is scarcest, to answer a question people ask once. It belongs with the
     other questions. */
  .cmp {
    display: grid;
    grid-template-columns: 1fr 1fr;
    gap: 0 24px;
    margin: 18px 0 22px;
  }
  .cmp-head {
    font-size: 14px;
    font-weight: 500;
    color: var(--text);
    padding-bottom: 10px;
  }
  .cmp-head:first-child { display: none; }
  .cmp-tier {
    display: inline-block;
    margin-left: 6px;
    font-size: 10.5px;
    font-weight: 600;
    letter-spacing: 0.03em;
    text-transform: uppercase;
    padding: 2px 6px;
    border-radius: 3px;
    vertical-align: 1px;
  }
  .cmp-tier.strongest { background: rgba(176,141,87,0.15); color: var(--brass); }
  .cmp-tier.strong { background: rgba(107,147,181,0.15); color: var(--signal); }
  .cmp-row {
    grid-column: 1 / -1;
    font-size: 11px;
    text-transform: uppercase;
    letter-spacing: 0.05em;
    color: var(--text-dim);
    padding: 13px 0 6px;
    border-top: 1px solid var(--border);
  }
  .cmp-val {
    display: flex;
    align-items: flex-start;
    gap: 8px;
    font-size: 14px;
    line-height: 1.5;
    color: var(--text-muted);
    padding-bottom: 12px;
  }
  .cmp-val .mk {
    width: 15px; height: 15px;
    flex-shrink: 0;
    margin-top: 2px;
    fill: none;
    stroke-width: 2.2;
    stroke-linecap: round;
    stroke-linejoin: round;
  }
  .cmp-val.yes { color: var(--text); }
  .cmp-val.yes .mk { stroke: var(--brass); }
  .cmp-val.no .mk { stroke: var(--text-dim); }
  /* Only needed once the columns stack and a value loses the header above it. */
  .cmp-who { display: none; }
  @media (max-width: 640px) {
    .cmp { grid-template-columns: 1fr; }
    .cmp-head { display: none; }
    .cmp-who { display: inline; color: var(--text-dim); }
    .cmp-val { padding-bottom: 7px; }
  }

  .faq-item {
    border-top: 1px solid var(--border);
  }
  .faq-item:last-child { border-bottom: 1px solid var(--border); }
  .faq-q {
    width: 100%;
    background: none;
    border: none;
    color: var(--text);
    font-family: var(--sans);
    font-size: 16px;
    font-weight: 500;
    text-align: left;
    padding: 22px 40px 22px 0;
    cursor: pointer;
    position: relative;
    line-height: 1.5;
  }
  .faq-q::after {
    content: '+';
    position: absolute;
    right: 8px;
    top: 20px;
    font-size: 20px;
    color: var(--brass);
    font-weight: 400;
  }
  .faq-item.open .faq-q::after { content: '−'; }
  .faq-a {
    display: none;
    padding: 0 60px 26px 0;
    font-size: 15px;
    color: var(--text-muted);
    line-height: 1.75;
    max-width: 660px;
  }
  .faq-item.open .faq-a { display: block; }
  .faq-a p + p { margin-top: 14px; }
  .faq-a strong { color: var(--text); font-weight: 600; }

  /* ---------- Footer ---------- */
  .footer-mark {
    /* inline-block so the link shrink-wraps the mark. Left inline it lays out as
       a full-width box and a click on empty footer navigates home from nowhere
       near the logo — the same bug the rail's brand already had. */
    display: inline-block;
    opacity: 0.75;
  }
  .footer-mark:hover { opacity: 1; }
  .footer-mark:focus-visible { outline: 2px solid var(--brass-dim); outline-offset: 3px; border-radius: 2px; }
  /* Smaller than the header's, and it inherits the same alpha-mask treatment, so
     it takes --text in both themes with no second asset. */
  .footer-mark .mark-img { width: 118px; height: 35px; }
  footer {
    padding: 44px 0;
    border-top: 1px solid var(--border);
  }
  footer .wrap {
    display: flex;
    justify-content: space-between;
    align-items: center;
    gap: 24px;
    font-size: 13px;
    color: var(--text-dim);
  }
  .footer-right {
    display: flex;
    align-items: center;
    gap: 24px;
  }
  .footer-link {
    background: none;
    border: none;
    color: var(--text-dim);
    font-family: var(--sans);
    font-size: 13px;
    cursor: pointer;
    text-decoration: underline;
    text-underline-offset: 3px;
    padding: 0;
  }
  .footer-link:hover { color: var(--text-muted); }

  /* ---------- Contact modal ---------- */
  .modal-overlay {
    display: none;
    position: fixed;
    inset: 0;
    background: rgba(10, 12, 16, 0.72);
    z-index: 50;
    align-items: center;
    justify-content: center;
    padding: 24px;
  }
  .modal-overlay.open { display: flex; }
  .modal {
    background: var(--surface);
    border: 1px solid var(--border);
    border-radius: 4px;
    max-width: 440px;
    width: 100%;
    padding: 32px;
  }
  .modal h3 {
    font-family: var(--serif);
    font-size: 21px;
    font-weight: 500;
    margin-bottom: 8px;
  }
  .modal p.modal-note {
    font-size: 13.5px;
    color: var(--text-muted);
    margin-bottom: 22px;
    line-height: 1.6;
  }
  .field { margin-bottom: 16px; }
  .field label {
    display: block;
    font-size: 12.5px;
    color: var(--text-dim);
    margin-bottom: 6px;
  }
  .field input, .field textarea {
    width: 100%;
    background: var(--bg);
    border: 1px solid var(--border);
    border-radius: 3px;
    color: var(--text);
    font-family: var(--sans);
    font-size: 14.5px;
    padding: 10px 12px;
  }
  .field input:focus, .field textarea:focus {
    outline: 2px solid var(--signal);
    outline-offset: 1px;
  }
  .field textarea { min-height: 96px; resize: vertical; }
  .modal-actions {
    display: flex;
    justify-content: space-between;
    align-items: center;
    margin-top: 22px;
  }
  .modal-close {
    background: none;
    border: none;
    color: var(--text-dim);
    font-size: 13.5px;
    cursor: pointer;
    text-decoration: underline;
  }
  .modal-status {
    font-size: 13px;
    margin-top: 14px;
    min-height: 18px;
  }
  .modal-status.ok { color: #7fae8a; }
  .modal-status.err { color: #b57a7a; }

  @media (max-width: 760px) {
    /* The lockup is wider than the text wordmark it replaced (120px against
       103px), and at 375px those 17px are what pushes the nav onto a second
       row. Scoped to .mark-img so it cannot reach anything else — the sibling
       of the rule this project already had to scope after an unscoped one hid
       the Close button on two panels. */
    .mark-img { width: 104px; height: 31px; }
    .hero-grid, .why-grid { grid-template-columns: 1fr; }
    .steps { grid-template-columns: 1fr; gap: 32px; }
    h1 { font-size: 34px; }
    .hero { padding: 56px 0 56px; }
    .lede { font-size: 16px; margin-top: 20px; }
    .cta-row {
      flex-direction: column;
      align-items: flex-start;
      gap: 14px;
      margin-top: 30px;
    }
    nav a { margin-left: 18px; }
    .section, .why, .faq { padding: 56px 0; }
    .section-head { margin-bottom: 36px; }
    .faq h2 { margin-bottom: 32px; }
    .faq-q { font-size: 15.5px; padding: 20px 36px 20px 0; }
    .faq-a { padding-right: 12px; }
    footer { padding: 32px 0 40px; }
    footer .wrap {
      flex-direction: column;
      align-items: flex-start;
      gap: 14px;
    }
    .footer-right {
      flex-direction: column;
      align-items: flex-start;
      gap: 14px;
    }
    .footer-link { text-align: left; }
  }

/* ── Accessibility utilities ─────────────────────────────────────────────
   Added 9 Sep 2026 with the <main> landmarks and chat.html's h1.

   EVERY COLOUR HERE CARRIES A var() FALLBACK ON PURPOSE. These same two rules
   go into three stylesheets that deliberately do not share a :root, and this
   repo has already paid for that once: --brass-dim existed in index.css and not
   chat.css, and an undefined custom property invalidates the whole declaration
   rather than falling back, so a button computed to transparent and every focus
   ring went invisible. A literal fallback cannot fail that way. */

/* The first focusable thing in the document, and off-screen until it is
   focused — so it costs a sighted visitor nothing and saves a keyboard one a
   full pass through the navigation on every load. Not display:none, which
   would take it out of the focus order and defeat the point entirely. */
.skip-link {
  position: absolute;
  left: -9999px;
  top: 0;
  z-index: 200;
}
.skip-link:focus {
  left: 10px;
  top: 10px;
  padding: 10px 14px;
  background: var(--surface, #16181d);
  color: var(--text, #e9e8e4);
  border: 1px solid var(--brass, #b08d57);
  border-radius: 8px;
  font: 500 14px/1.2 'IBM Plex Sans', system-ui, -apple-system, sans-serif;
  text-decoration: none;
}

/* Announced, never drawn. clip-path is the modern half and clip the legacy one;
   both are kept because dropping either loses a browser somebody still uses. */
.sr-only {
  position: absolute;
  width: 1px;
  height: 1px;
  padding: 0;
  margin: -1px;
  overflow: hidden;
  clip: rect(0 0 0 0);
  clip-path: inset(50%);
  white-space: nowrap;
  border: 0;
}