:root {
  --paper: #F3F6F4;
  --surface: #FFFFFF;
  --tint: #E8EEEA;
  --ink: #15272C;
  --ink-soft: #4C5F63;
  --line: #D6DEDA;
  --accent: #0E8C72;
  --accent-deep: color-mix(in srgb, var(--accent), #000 30%);
  --accent-soft: color-mix(in srgb, var(--accent) 13%, var(--surface));
  --accent-line: color-mix(in srgb, var(--accent) 40%, var(--line));
  --danger: #B23B3B;
  --shadow: 22px 30px 60px -40px rgba(9, 40, 34, .40);
  --sans: system-ui, -apple-system, "Segoe UI", Roboto, Helvetica, Arial, sans-serif;
  --mono: ui-monospace, "SF Mono", "Cascadia Code", "Menlo", Consolas, monospace;
}
@media (prefers-color-scheme: dark) {
  :root {
    --paper: #0E1618; --surface: #152327; --tint: #1A2A2E; --ink: #E7EDEA;
    --ink-soft: #9BADAE; --line: #263A3E; --danger: #E08A8A;
    --shadow: 22px 30px 60px -42px rgba(0, 0, 0, .75);
  }
}
:root[data-theme="light"] {
  --paper: #F3F6F4; --surface: #FFFFFF; --tint: #E8EEEA; --ink: #15272C;
  --ink-soft: #4C5F63; --line: #D6DEDA; --danger: #B23B3B;
  --shadow: 22px 30px 60px -40px rgba(9, 40, 34, .40);
}
:root[data-theme="dark"] {
  --paper: #0E1618; --surface: #152327; --tint: #1A2A2E; --ink: #E7EDEA;
  --ink-soft: #9BADAE; --line: #263A3E; --danger: #E08A8A;
  --shadow: 22px 30px 60px -42px rgba(0, 0, 0, .75);
}

* { box-sizing: border-box; }
html { -webkit-text-size-adjust: 100%; }
body {
  margin: 0; background: var(--paper); color: var(--ink);
  font-family: var(--sans); line-height: 1.62; font-size: 17px;
  -webkit-font-smoothing: antialiased;
}
.wrap { max-width: 940px; margin: 0 auto; padding: 0 24px 80px; }
.mono { font-family: var(--mono); }
.eyebrow { font-family: var(--mono); font-size: .74rem; letter-spacing: .18em; text-transform: uppercase; color: var(--accent); font-weight: 600; }
h1, h2, h3 { text-wrap: balance; line-height: 1.12; }
a { color: var(--accent); }
button { font-family: inherit; }
.hidden { display: none !important; }

/* ================= PROMPT (home) ================= */
#home { padding-top: 74px; }
.brand-mark { display: block; width: 64px; height: 64px; margin-bottom: 22px; }
#home .eyebrow { display: block; margin-bottom: 26px; }
#home h1 { font-size: clamp(2.3rem, 6.5vw, 3.9rem); margin: 0; letter-spacing: -.02em; font-weight: 800; }
.home-sub { color: var(--ink-soft); max-width: 60ch; margin: 20px 0 0; font-size: 1.04rem; }

/* ================= ABOUT / LEGAL PAGES ================= */
#about { padding-top: 40px; }
#about .back { display: inline-block; margin-bottom: 26px; text-decoration: none; }
#about .eyebrow { display: block; margin-bottom: 18px; }
#about h1 { font-size: clamp(2rem, 5.5vw, 3.1rem); margin: 0; letter-spacing: -.02em; font-weight: 800; }
#about .home-sub + .home-sub { margin-top: 14px; }

.prompt { margin: 32px 0 20px; display: flex; gap: 12px; max-width: 620px; flex-wrap: wrap; }
.prompt input {
  flex: 1 1 320px; font-size: 1.05rem; font-family: var(--sans);
  padding: 15px 18px; border-radius: 12px;
  border: 1px solid var(--line); background: var(--surface); color: var(--ink);
}
.prompt input:focus { outline: 2px solid var(--accent); outline-offset: 1px; border-color: transparent; }
.prompt button {
  flex: 0 0 auto; font-size: 1rem; font-weight: 600; cursor: pointer;
  padding: 15px 26px; border-radius: 12px; border: none;
  background: var(--accent); color: #fff; transition: filter .15s, transform .1s;
}
.prompt button:hover:not(:disabled) { filter: brightness(1.06); }
.prompt button:active:not(:disabled) { transform: translateY(1px); }
.prompt button:disabled { opacity: .55; cursor: default; }
.examples { display: flex; flex-wrap: wrap; gap: 9px; align-items: center; }
.examples.recent { margin-top: 12px; }
.examples span { font-family: var(--mono); font-size: .72rem; letter-spacing: .1em; text-transform: uppercase; color: var(--ink-soft); }
.chip {
  cursor: pointer; background: var(--surface); border: 1px solid var(--line);
  color: var(--ink-soft); border-radius: 999px; padding: 6px 14px; font-size: .85rem;
  max-width: 220px; overflow: hidden; text-overflow: ellipsis; white-space: nowrap;
  transition: border-color .15s, color .15s;
}
.chip:hover { border-color: var(--accent); color: var(--accent); }
.chip:focus-visible { outline: 2px solid var(--accent); outline-offset: 2px; }
.home-note { margin-top: 34px; font-family: var(--mono); font-size: .78rem; color: var(--ink-soft); letter-spacing: .02em; max-width: 60ch; }
.home-error { margin-top: 24px; color: var(--danger); font-size: .95rem; max-width: 60ch; }
#homeRetry { margin-top: 14px; }

/* ================= LOADING ================= */
#loading { padding-top: 120px; text-align: center; }
.spinner { width: 46px; height: 46px; margin: 0 auto 26px; border-radius: 50%;
  border: 3px solid var(--line); border-top-color: var(--accent); animation: spin 1s linear infinite; }
@media (prefers-reduced-motion: reduce) { .spinner { animation: none; border-top-color: var(--accent); } }
@keyframes spin { to { transform: rotate(360deg); } }
#loading .status { font-family: var(--mono); color: var(--ink-soft); font-size: .95rem; }
#loading .status b { color: var(--ink); font-weight: 600; }

/* ================= READER ================= */
@media (prefers-reduced-motion: no-preference) {
  #reader.enter { animation: fade .4s ease both; }
}
@keyframes fade { from { opacity: 0; transform: translateY(8px); } to { opacity: 1; transform: none; } }

.topbar { display: flex; align-items: center; justify-content: space-between; gap: 14px; padding: 30px 0 0; flex-wrap: wrap; }
.topbar-right { display: flex; align-items: center; gap: 12px; flex-wrap: wrap; }
.back { background: var(--surface); border: 1px solid var(--line); color: var(--ink);
  border-radius: 10px; padding: 9px 15px; font-size: .86rem; cursor: pointer;
  font-family: var(--mono); letter-spacing: .02em; transition: border-color .15s, background .15s, color .15s; }
.back:hover { border-color: var(--accent); color: var(--accent); }
.back:focus-visible { outline: 2px solid var(--accent); outline-offset: 2px; }
.back.copied { background: var(--accent); border-color: var(--accent); color: #fff; }
.back.speaking { background: var(--accent-deep); border-color: var(--accent-deep); color: #fff; }
.back:disabled { opacity: .6; cursor: default; }
.field-chip { font-family: var(--mono); font-size: .72rem; letter-spacing: .14em; text-transform: uppercase; color: var(--accent); font-weight: 700; border: 1px solid var(--accent-line); border-radius: 999px; padding: 6px 14px; }

.demo-banner { margin-top: 22px; background: var(--accent-soft); border: 1px solid var(--accent-line);
  border-radius: 12px; padding: 13px 18px; font-size: .88rem; color: var(--ink); }
.demo-banner b { font-family: var(--mono); text-transform: uppercase; letter-spacing: .08em; font-size: .72rem; color: var(--accent); }

.rhero { padding: 38px 0 38px; border-bottom: 1px solid var(--line); }
.rhero .eyebrow { display: block; margin-bottom: 22px; }
.rhero h1 { font-size: clamp(2.2rem, 6vw, 3.8rem); margin: 0; letter-spacing: -.02em; font-weight: 800; }
.byline { font-family: var(--mono); color: var(--ink-soft); margin: 18px 0 0; font-size: .9rem; }
.thesis { font-size: clamp(1.12rem, 2.4vw, 1.36rem); max-width: 36ch; margin: 26px 0 0; line-height: 1.42; font-weight: 500; }
.thesis strong { color: var(--accent); font-weight: 700; }
.pareto { margin-top: 34px; display: grid; grid-template-columns: auto 1fr; gap: 20px; align-items: center; background: var(--tint); border: 1px solid var(--line); border-radius: 14px; padding: 20px 24px; max-width: 640px; }
.pareto .num { font-family: var(--mono); font-size: 2.4rem; font-weight: 700; color: var(--accent); line-height: 1; }
.pareto .pct { font-size: 1.3rem; color: var(--ink-soft); }
.pareto p { margin: 0; font-size: .95rem; color: var(--ink-soft); }

section { padding-top: 58px; }
.sec-head { display: flex; align-items: baseline; gap: 14px; margin-bottom: 8px; }
.sec-head .idx { font-family: var(--mono); color: var(--accent); font-size: .8rem; font-weight: 600; }
h2 { font-size: clamp(1.5rem, 4vw, 2.05rem); margin: 0; letter-spacing: -.01em; }
.lede { color: var(--ink-soft); max-width: 62ch; margin: 14px 0 30px; }

.fw-card { background: var(--surface); border: 1px solid var(--line); border-radius: 20px; box-shadow: var(--shadow); padding: 34px; }
.fw-card.is-loop { display: grid; grid-template-columns: minmax(270px, 1fr) 1fr; gap: 30px 44px; align-items: center; }
.fw-card svg { width: 100%; height: auto; display: block; }
.loop-legend { display: flex; flex-direction: column; gap: 18px; }
.leg-item { display: grid; grid-template-columns: auto 1fr; gap: 3px 14px; align-items: start; }
.leg-item .dot { width: 13px; height: 13px; border-radius: 50%; margin-top: 6px; }
.leg-item h4 { margin: 0; font-size: 1rem; font-family: var(--mono); text-transform: uppercase; letter-spacing: .05em; }
.leg-item p { margin: 2px 0 0; grid-column: 2; font-size: .89rem; color: var(--ink-soft); }

.pgrid { display: grid; grid-template-columns: repeat(3, 1fr); gap: 16px; }
.ptile { border: 1px solid var(--line); border-radius: 14px; padding: 20px; background: var(--accent-soft); }
.ptile .pn { font-family: var(--mono); font-size: .78rem; font-weight: 700; color: var(--accent); letter-spacing: .08em; }
.ptile h4 { margin: 8px 0 7px; font-size: 1.05rem; }
.ptile p { margin: 0; font-size: .88rem; color: var(--ink-soft); }

.cards { display: grid; grid-template-columns: repeat(2, 1fr); gap: 18px; }
.card { background: var(--surface); border: 1px solid var(--line); border-radius: 16px; padding: 26px 26px 24px; position: relative; overflow: hidden; }
.card::before { content: ""; position: absolute; left: 0; top: 0; bottom: 0; width: 4px; background: var(--accent); }
.card .no { font-family: var(--mono); font-size: .76rem; letter-spacing: .1em; color: var(--ink-soft); font-weight: 600; }
.card h3 { font-size: 1.15rem; margin: 8px 0 10px; }
.card p { margin: 0; font-size: .93rem; color: var(--ink-soft); }
.card .eg { display: block; margin-top: 14px; padding-top: 12px; border-top: 1px solid var(--line); font-size: .84rem; color: var(--ink); }
.card .eg b { font-family: var(--mono); font-size: .71rem; text-transform: uppercase; letter-spacing: .09em; color: var(--accent); display: block; margin-bottom: 3px; }
.card.wide { grid-column: 1 / -1; }

/* Category-browse picks: cards that act as buttons */
.book-pick { cursor: pointer; transition: border-color .15s, transform .1s; }
.book-pick:hover { border-color: var(--accent); }
.book-pick:active { transform: translateY(1px); }
.book-pick:focus-visible { outline: 2px solid var(--accent); outline-offset: 2px; }
.book-pick .pick-author { font-family: var(--mono); font-size: .78rem; color: var(--ink-soft); margin: -4px 0 10px; }
.book-pick .eg b { margin-bottom: 0; }

.impl-intro { background: var(--tint); border: 1px solid var(--line); border-radius: 14px; padding: 18px 22px; font-size: .9rem; color: var(--ink-soft); margin-bottom: 28px; }
.impl-intro strong { color: var(--ink); font-weight: 700; }
.steps { display: flex; flex-direction: column; gap: 14px; }
.step { display: grid; grid-template-columns: auto 1fr; gap: 20px; background: var(--surface); border: 1px solid var(--line); border-radius: 14px; padding: 22px 24px; align-items: start; }
.step .frame { font-family: var(--mono); font-size: .66rem; text-transform: uppercase; letter-spacing: .07em; color: var(--accent); font-weight: 700; writing-mode: vertical-rl; transform: rotate(180deg); border-left: 2px solid var(--accent); padding-left: 8px; align-self: stretch; }
.step h3 { font-size: 1.05rem; margin: 0 0 6px; }
.step p { margin: 0; font-size: .92rem; color: var(--ink-soft); }

footer { margin-top: 60px; padding-top: 26px; border-top: 1px solid var(--line); display: flex; flex-wrap: wrap; justify-content: space-between; gap: 12px; font-family: var(--mono); font-size: .78rem; color: var(--ink-soft); letter-spacing: .03em; }
footer button.linklike { background: none; border: none; color: var(--accent); cursor: pointer; font: inherit; padding: 0; }

/* Site-wide footer (home + reader + static pages) */
.sitefoot { margin-top: 70px; }
.sitefoot-links { display: flex; flex-wrap: wrap; gap: 8px 20px; }
.sitefoot-links a { color: var(--ink-soft); text-decoration: none; }
.sitefoot-links a:hover { color: var(--accent); text-decoration: underline; }

/* Legal pages */
.legal-callout { background: var(--accent-soft); border: 1px solid var(--accent-line); border-radius: 14px; padding: 18px 22px; margin-top: 30px; font-size: .95rem; }
.legal-callout b { color: var(--accent); }
.legal h2 { font-size: 1.25rem; margin-top: 0; }
.legal section { padding-top: 34px; }
.legal p, .legal li { font-size: .95rem; color: var(--ink-soft); }
.legal p b, .legal li b { color: var(--ink); }
.legal .effective { font-family: var(--mono); font-size: .78rem; color: var(--ink-soft); margin-top: 16px; }
.cta-link { display: inline-block; margin-top: 6px; background: var(--accent); color: #fff; text-decoration: none; font-weight: 600; padding: 13px 24px; border-radius: 12px; }
.cta-link:hover { filter: brightness(1.06); color: #fff; }

@media (max-width: 720px) {
  .fw-card.is-loop { grid-template-columns: 1fr; }
  .cards { grid-template-columns: 1fr; }
  .pgrid { grid-template-columns: 1fr; }
  .pareto { grid-template-columns: 1fr; gap: 8px; }
}
@media (max-width: 560px) {
  body { font-size: 16px; }
  .wrap { padding: 0 18px 64px; }
  #home { padding-top: 40px; }
  .prompt { flex-direction: column; gap: 10px; }
  .prompt input { flex: 1 1 auto; width: 100%; }
  .prompt button { width: 100%; }
  .chip { max-width: 100%; }
  .fw-card { padding: 22px; }
  .step { padding: 18px 16px; gap: 14px; }
  .rhero { padding: 28px 0; }
  .topbar-right { width: 100%; }
}
@media (max-width: 380px) { .pgrid { grid-template-columns: 1fr; } }