/* The retrieval section: the book's typography on a plain page. */
body { min-height: 100vh; padding: 0 16px 80px; }
.topbar { max-width: 1100px; margin: 0 auto; padding: 22px 12px; display: flex; align-items: center; gap: 18px; font: 500 12px/1 var(--mono); letter-spacing: .06em; color: var(--muted); }
.brand { font: 500 19px/1 var(--serif); letter-spacing: 0; color: var(--strong); text-decoration: none; }
.crumb { text-transform: uppercase; position: relative; top: 2.5px; }
.modes { margin-left: auto; display: flex; gap: 4px; }
.modes button { border: 0; background: none; cursor: pointer; padding: 8px 12px; border-radius: 999px; font: 500 12px/1 var(--mono); letter-spacing: .06em; text-transform: uppercase; color: var(--muted); }
.modes button:hover { color: var(--strong); }
.modes button[aria-current="true"] { background: var(--card); box-shadow: var(--lift); color: var(--strong); }
.wrap { max-width: 760px; margin: 0 auto; }
.intro { margin: 48px 0 36px; }
.intro h1 { font: 400 clamp(40px, 6vw, 64px)/1 var(--serif); color: var(--strong); letter-spacing: -.01em; }
.intro .sub { font: italic 400 clamp(19px, 2.2vw, 24px)/1.35 var(--serif); color: var(--muted); margin-top: 14px; max-width: 620px; }
.intro .how { margin-top: 14px; max-width: 62ch; }
.card { background: var(--card); border-radius: 14px; box-shadow: var(--lift); padding: 28px 32px 30px; margin: 0 0 18px; }
.kicker { font: 500 12px/1 var(--mono); letter-spacing: .12em; color: var(--muted); text-transform: uppercase; }
.kicker a { color: inherit; text-decoration: none; }
.kicker a:hover { color: var(--strong); }
.card h2 { font: 400 26px/1.2 var(--serif); color: var(--strong); margin: 12px 0 14px; }
.card p { margin: 0 0 12px; max-width: 62ch; }
.choices { list-style: none; padding: 0; margin: 8px 0 0; display: grid; gap: 6px; }
.choices button { width: 100%; display: flex; gap: 12px; align-items: baseline; text-align: left; cursor: pointer; border: 1px solid var(--faint); background: var(--card); border-radius: 8px; padding: 10px 12px; font: 15px/1.4 var(--sans); color: var(--text); }
.choices button:hover:not(:disabled) { border-color: var(--mid); color: var(--strong); }
.choices button:disabled { cursor: default; }
.choices .letter { font: 500 12px var(--mono); color: var(--muted); }
.choices button.right { border-color: #2f8f5b; background: #eef7f1; color: var(--strong); }
.choices button.right .letter { color: #2f8f5b; }
.choices button.wrong { border-color: var(--red); background: #fcefef; }
.choices button.wrong .letter { color: var(--red); }
.why { margin-top: 14px; padding: 10px 0 2px 16px; border-left: 1px solid var(--mid); font-size: 15px; }
.why p { margin: 0 0 8px; }
.why .eq { font: 400 20px/1.3 var(--serif); color: var(--strong); padding: 4px 0 4px 12px; border-left: 1px solid var(--mid); margin: 6px 0; }
.why i { font-family: var(--serif); font-size: 1.08em; }
.card .next { margin-top: 16px; display: flex; justify-content: space-between; align-items: center; gap: 12px; flex-wrap: wrap; }
.btn { border: 1px solid var(--faint); background: var(--card); color: var(--hi); cursor: pointer; font: 500 12px var(--mono); letter-spacing: .06em; padding: 9px 14px; border-radius: 999px; text-decoration: none; text-transform: uppercase; }
.btn:hover { border-color: var(--mid); color: var(--strong); }
.btn.primary { background: var(--strong); color: var(--card); border-color: var(--strong); }
.btn.primary:hover { background: #000; }
.tally { font: 12px/1 var(--mono); color: var(--muted); letter-spacing: .04em; }
.progress { display: grid; gap: 10px; }
.progress .row { display: grid; grid-template-columns: 56px 1fr 160px 70px; gap: 14px; align-items: center; background: var(--card); border-radius: 10px; box-shadow: var(--lift); padding: 12px 16px; text-decoration: none; color: inherit; }
.progress .no { font: 11px var(--mono); color: var(--muted); letter-spacing: .04em; }
.progress .t { font: 400 20px/1.2 var(--serif); color: var(--strong); }
.progress .bar { height: 7px; border-radius: 4px; background: #ecece8; overflow: hidden; }
.progress .bar i { display: block; height: 100%; background: #3d63a8; }
.progress .pct { font: 12px var(--mono); color: var(--hi); text-align: right; font-variant-numeric: tabular-nums; }
.pick { display: grid; grid-template-columns: repeat(auto-fill, minmax(220px, 1fr)); gap: 10px; margin-bottom: 18px; }
.pick label { display: flex; gap: 10px; align-items: baseline; background: var(--card); border-radius: 10px; box-shadow: var(--lift); padding: 12px 14px; cursor: pointer; font: 15px var(--sans); }
.pick label span { font: 11px var(--mono); color: var(--muted); }
.links { list-style: none; padding: 0; margin: 12px 0 0; display: grid; gap: 8px; counter-reset: link; }
.links li { position: relative; padding: 10px 14px 10px 44px; border: 1px solid var(--faint); border-radius: 8px; background: var(--card); font-size: 15px; line-height: 1.45; }
.links li::before { counter-increment: link; content: counter(link); position: absolute; left: 14px; top: 10px; font: 500 12px var(--mono); color: var(--muted); }
.links li.hidden { color: transparent; user-select: none; background: #f4f4f1; border-style: dashed; }
.links li.hidden::after { content: '· · ·'; position: absolute; left: 44px; top: 10px; color: var(--lo); }
.self { display: flex; gap: 8px; margin-top: 16px; flex-wrap: wrap; align-items: center; }
.self .q { font: 15px var(--sans); color: var(--text); margin-right: auto; }
textarea.chain { width: 100%; min-height: 110px; border: 1px solid var(--faint); border-radius: 8px; padding: 10px 12px; font: 15px/1.5 var(--sans); color: var(--strong); background: var(--card); resize: vertical; }
textarea.chain:focus { outline: none; border-color: var(--mid); }
.done { text-align: center; padding: 20px 0 10px; }
.done h2 { font: 400 32px/1.1 var(--serif); color: var(--strong); margin-bottom: 10px; }
.done p { color: var(--muted); }
.empty { color: var(--muted); font-style: italic; font-family: var(--serif); font-size: 19px; }
@media (max-width: 600px) {
  body { padding: 0 12px 56px; }
  .topbar { padding: 16px 4px; flex-wrap: wrap; gap: 10px; }
  .modes { margin-left: 0; width: 100%; justify-content: space-between; }
  .modes button { padding: 8px 8px; font-size: 11px; }
  .intro { margin: 24px 0 20px; }
  .card { padding: 20px 18px 22px; }
  .progress .row { grid-template-columns: 1fr 70px; }
  .progress .no, .progress .bar { display: none; }
}