:root {
  --ink: #1c2530;
  --ink-soft: #4a5562;
  --paper: #fbfaf7;
  --card: #ffffff;
  --line: #e4e0d8;
  --brand: #1f3a5f;
  --brand-ink: #ffffff;
  --accent: #c8862a;
  --accent-soft: #fbf1e2;
  --good: #2f7a4d;
  --bad: #a23b2a;
  --radius: 10px;
  --wrap: 44rem;
  --serif: Georgia, "Iowan Old Style", "Times New Roman", serif;
  --sans: system-ui, -apple-system, "Segoe UI", Roboto, sans-serif;
}
@media (prefers-color-scheme: dark) {
  :root {
    --ink: #e9e6e0; --ink-soft: #b3aca1; --paper: #14191f; --card: #1c232b;
    --line: #2e3842; --brand: #8fb3e0; --brand-ink: #10161d; --accent: #e3a54f;
    --accent-soft: #2a2318; --good: #6cc08e; --bad: #e08a7a;
  }
}
* { box-sizing: border-box; }
html { -webkit-text-size-adjust: 100%; }
body { margin: 0; background: var(--paper); color: var(--ink); font: 1.0625rem/1.65 var(--sans); }
a { color: var(--brand); }
img { max-width: 100%; height: auto; }
.wrap { max-width: var(--wrap); margin: 0 auto; padding: 0 1rem; }

header.top { border-bottom: 1px solid var(--line); background: var(--card); }
header.top .wrap { display: flex; align-items: center; justify-content: space-between; gap: 1rem; min-height: 3.5rem; flex-wrap: wrap; }
.logo { font: 700 1.05rem/1.2 var(--serif); color: var(--ink); text-decoration: none; letter-spacing: .01em; }
.logo span { color: var(--accent); }
nav a { margin-left: 1rem; font-size: .95rem; text-decoration: none; }

h1, h2, h3 { font-family: var(--serif); line-height: 1.25; }
h1 { font-size: clamp(1.8rem, 6vw, 2.6rem); margin: 2rem 0 .75rem; }
h2 { font-size: 1.45rem; margin: 2.25rem 0 .5rem; }
h3 { font-size: 1.15rem; margin: 1.5rem 0 .25rem; }
.lede { font-size: 1.15rem; color: var(--ink-soft); }

.hero { padding: 1rem 0 2rem; }
.hero-img { display: block; width: 100%; aspect-ratio: 21 / 9; object-fit: cover; object-position: 40% 60%; border-radius: var(--radius); margin-top: 1.25rem; }
.hero h1 { margin-top: 1.5rem; }
.offer { display: grid; gap: 1.25rem; align-items: center; }
.offer .cover { width: 62%; max-width: 260px; margin: 0 auto; border-radius: 4px 8px 8px 4px; box-shadow: 0 18px 40px rgba(0,0,0,.28), -6px 0 0 rgba(0,0,0,.15) inset; transform: rotate(-2deg); }
.offer .signup { margin: 0; }
@media (min-width: 40rem) { .offer { grid-template-columns: 220px 1fr; } .offer .cover { width: 100%; } }
.card { background: var(--card); border: 1px solid var(--line); border-radius: var(--radius); padding: 1.25rem; margin: 1.25rem 0; }
.signup h2 { margin-top: 0; }
.signup form { display: grid; gap: .6rem; }
label { font-weight: 600; font-size: .95rem; }
input { font: inherit; padding: .7rem .8rem; border: 1px solid var(--line); border-radius: 8px; background: var(--paper); color: var(--ink); width: 100%; }
input:focus-visible, button:focus-visible, a:focus-visible { outline: 3px solid var(--accent); outline-offset: 2px; }
button, .button { font: 600 1rem/1.2 var(--sans); background: var(--brand); color: var(--brand-ink); border: 0; border-radius: 8px; padding: .85rem 1.1rem; cursor: pointer; text-decoration: none; display: inline-block; text-align: center; }
button:hover, .button:hover { filter: brightness(1.1); }
.fine { font-size: .85rem; color: var(--ink-soft); }
ul.checks { padding-left: 0; list-style: none; }
ul.checks li { padding-left: 1.6rem; position: relative; margin: .4rem 0; }
ul.checks li::before { content: "✓"; position: absolute; left: 0; color: var(--good); font-weight: 700; }

.chapter blockquote, .disclaimer { border-left: 4px solid var(--accent); background: var(--accent-soft); margin: 1.5rem 0; padding: .75rem 1rem; border-radius: 0 8px 8px 0; }
.chapter blockquote p { margin: .4rem 0; }
.chapter li { margin: .25rem 0; }
.cta-band { background: var(--brand); color: var(--brand-ink); border-radius: var(--radius); padding: 1.25rem; margin: 2rem 0; }
.cta-band a.button { background: var(--accent); color: #1c1408; }

.author { display: flex; gap: 1rem; align-items: flex-start; }
.author img { width: 120px; height: 120px; border-radius: 50%; object-fit: cover; flex: none; border: 3px solid var(--card); box-shadow: 0 0 0 1px var(--line); }
.author p { margin: 0; }
@media (max-width: 30rem) { .author { flex-direction: column; } }

/* calculator */
.calc { display: grid; gap: 1rem; }
.calc .field { display: grid; gap: .3rem; }
.calc .hint { font-size: .85rem; color: var(--ink-soft); }
.money { position: relative; }
.money::before { content: "$"; position: absolute; left: .8rem; top: 50%; transform: translateY(-50%); color: var(--ink-soft); }
.money input { padding-left: 1.6rem; }
.pct { position: relative; }
.pct::after { content: "%"; position: absolute; right: .8rem; top: 50%; transform: translateY(-50%); color: var(--ink-soft); }
.results { display: grid; gap: .5rem; }
.result { display: flex; justify-content: space-between; gap: 1rem; padding: .55rem 0; border-bottom: 1px solid var(--line); }
.result strong { font-variant-numeric: tabular-nums; }
.result.big { font-size: 1.2rem; border-bottom: 0; padding-top: .8rem; }
.result.big strong { color: var(--brand); }
.verdict { padding: .75rem 1rem; border-radius: 8px; font-weight: 600; }
.verdict.ok { background: color-mix(in srgb, var(--good) 15%, transparent); color: var(--good); }
.verdict.no { background: color-mix(in srgb, var(--bad) 15%, transparent); color: var(--bad); }
@media (min-width: 40rem) { .calc { grid-template-columns: 1fr 1fr; } .calc .wide { grid-column: 1 / -1; } }

/* interactive chapter: terms */
button.term { font: inherit; color: inherit; background: none; border: 0; padding: 0; cursor: pointer; text-decoration: underline dotted var(--accent) 2px; text-underline-offset: 3px; border-radius: 3px; }
button.term:hover { background: var(--accent-soft); text-decoration-style: solid; }
button.term.demo { cursor: default; }
.tip { font-size: .9rem; color: var(--ink-soft); background: var(--card); border: 1px dashed var(--line); border-radius: 8px; padding: .5rem .75rem; }
.term-pop { position: absolute; z-index: 50; background: var(--card); color: var(--ink); border: 1px solid var(--line); border-radius: 12px; box-shadow: 0 16px 40px rgba(0,0,0,.22); padding: 1rem 1.1rem; max-height: 70vh; overflow: auto; font-size: .95rem; }
.term-pop.sheet { position: fixed; left: 0; right: 0; bottom: 0; top: auto; width: auto; border-radius: 16px 16px 0 0; max-height: 75vh; }
.term-pop h3 { margin: 0 2rem .4rem 0; font-size: 1.15rem; }
.term-pop h4 { margin: .9rem 0 .3rem; font: 700 .75rem/1.2 var(--sans); text-transform: uppercase; letter-spacing: .08em; color: var(--ink-soft); }
.term-pop ul { margin: 0; padding-left: 1.1rem; }
.term-pop li { margin: .2rem 0; }
.tp-close { position: absolute; top: .5rem; right: .6rem; background: none; border: 0; font-size: 1.5rem; line-height: 1; color: var(--ink-soft); cursor: pointer; padding: .2rem .4rem; }
.tp-def { margin: 0; }
.tp-count { color: var(--ink-soft); font-size: .85rem; }
.tp-book li.locked { list-style: none; margin-left: -1.1rem; color: var(--ink-soft); }
.tp-book .lock { margin-right: .35rem; font-size: .8rem; }
.tp-sum { margin: 0 0 .3rem; font-size: .9rem; }
.tp-cta { margin: .6rem 0 0; font-size: .85rem; background: var(--accent-soft); border-radius: 6px; padding: .45rem .6rem; }
.flash { animation: flash 1.6s ease; }
@keyframes flash { 0%, 40% { background: var(--accent-soft); } 100% { background: transparent; } }

/* interactive chapter: tables */
.chapter table { width: 100%; border-collapse: collapse; margin: 1.25rem 0; font-size: .95rem; display: block; overflow-x: auto; }
.chapter th, .chapter td { border-bottom: 1px solid var(--line); padding: .55rem .6rem; text-align: left; vertical-align: top; }
.chapter thead th { background: var(--brand); color: var(--brand-ink); }
.chapter tbody tr:hover { background: var(--accent-soft); }

/* widgets */
.w { background: var(--card); border: 1px solid var(--line); border-radius: var(--radius); padding: 1.1rem; margin: 1.75rem 0; }
.w h3 { margin: 0; }
.w-sub { margin: .15rem 0 .9rem; font-size: .88rem; color: var(--ink-soft); }
.w-note { font-size: .95rem; margin: .75rem 0 0; }
.w-more { margin: .5rem 0 0; font-size: .95rem; }
.w-slider { display: grid; gap: .2rem; font-weight: 600; font-size: .9rem; margin-top: .6rem; }
.w-slider output { font-variant-numeric: tabular-nums; color: var(--brand); }
.w-slider input[type=range] { width: 100%; padding: 0; border: 0; background: none; accent-color: var(--accent); }
.w-grid { display: grid; gap: .25rem 1rem; }
@media (min-width: 40rem) { .w-grid { grid-template-columns: 1fr 1fr; } }
.w-tip { position: absolute; z-index: 60; max-width: 250px; background: var(--ink); color: var(--paper); font-size: .82rem; padding: .45rem .6rem; border-radius: 6px; pointer-events: none; }
.seg.seller { background: var(--brand); } .seg.you { background: var(--accent); } .seg.repairs { background: #8a6f55; } .seg.margin { background: #9aa6b2; }
.mf-cards { display: flex; align-items: stretch; gap: .4rem; }
.mf-card { flex: 1; border: 1px solid var(--line); border-radius: 10px; padding: .6rem; text-align: center; transition: transform .15s; }
.mf-card:hover, .mf-card:focus { transform: translateY(-2px); outline: 2px solid var(--accent); }
.mf-card.you { background: var(--accent-soft); }
.mf-who { font-size: .8rem; text-transform: uppercase; letter-spacing: .06em; color: var(--ink-soft); }
.mf-amt { font: 700 1.15rem/1.3 var(--serif); font-variant-numeric: tabular-nums; }
.mf-role { font-size: .78rem; color: var(--ink-soft); line-height: 1.35; }
.mf-arrow { align-self: center; color: var(--accent); font-weight: 700; }
.mf-bar, .dm-bar { display: flex; height: 22px; border-radius: 6px; overflow: hidden; margin: .9rem 0 .2rem; background: var(--line); }
.dm-bar { height: 34px; }
.mf-bar .seg, .dm-bar .seg { height: 100%; transition: width .2s; }
.dm-bar .seg:hover, .dm-bar .seg:focus { filter: brightness(1.15); outline: none; }
.dm-legend { list-style: none; padding: 0; margin: .5rem 0; display: grid; gap: .2rem; font-size: .9rem; }
.dm-legend i { display: inline-block; width: .8rem; height: .8rem; border-radius: 3px; margin-right: .4rem; vertical-align: -1px; }
.dm-legend i.seller { background: var(--brand); } .dm-legend i.you { background: var(--accent); } .dm-legend i.repairs { background: #8a6f55; } .dm-legend i.margin { background: #9aa6b2; }
@media (max-width: 30rem) { .mf-cards { flex-direction: column; } .mf-arrow { transform: rotate(90deg); } }
.tl-rail { list-style: none; padding: 0; margin: .5rem 0 0; display: flex; overflow-x: auto; gap: .2rem; }
.tl-rail li { flex: 1 0 4.5rem; position: relative; }
.tl-rail li::before { content: ""; position: absolute; top: 1rem; left: 0; right: 0; height: 3px; background: var(--line); }
.tl-rail li.done::before, .tl-rail li.on::before { background: var(--accent); }
.tl-rail button { position: relative; display: grid; justify-items: center; gap: .3rem; width: 100%; background: none; border: 0; cursor: pointer; padding: 0; color: var(--ink); font: inherit; }
.tl-dot { width: 2rem; height: 2rem; border-radius: 50%; display: grid; place-items: center; background: var(--card); border: 2px solid var(--line); font-weight: 700; font-size: .85rem; }
.tl-rail .done .tl-dot { border-color: var(--accent); }
.tl-rail .on .tl-dot { background: var(--accent); border-color: var(--accent); color: #1c1408; }
.tl-name { font-size: .72rem; line-height: 1.2; text-align: center; color: var(--ink-soft); }
.tl-panel { margin-top: .9rem; background: var(--paper); border-radius: 8px; padding: .8rem 1rem; }
.tl-panel h4 { margin: .1rem 0 .3rem; font-family: var(--serif); font-size: 1.05rem; }
.tl-panel p { margin: 0; }
.tl-when { font-size: .78rem; text-transform: uppercase; letter-spacing: .06em; color: var(--accent); font-weight: 700; }
.tl-nav { display: flex; justify-content: space-between; margin-top: .7rem; }
button.ghost { background: none; color: var(--brand); border: 1px solid var(--line); padding: .45rem .8rem; font-size: .9rem; }
button.ghost:disabled { opacity: .4; cursor: default; }
.qz { padding-left: 1.2rem; }
.qz-q { font-weight: 600; margin: .8rem 0 .4rem; }
.qz-opts { display: grid; gap: .35rem; }
.qz-opt { text-align: left; background: var(--paper); color: var(--ink); border: 1px solid var(--line); font-weight: 400; }
.qz-opt.right { border-color: var(--good); background: color-mix(in srgb, var(--good) 14%, transparent); }
.qz-opt.wrong { border-color: var(--bad); background: color-mix(in srgb, var(--bad) 14%, transparent); }
.qz-fb { font-size: .9rem; margin: .35rem 0 0; color: var(--ink-soft); }
.qz-score { font-weight: 700; }
.gl { list-style: none; padding: 0; columns: 2 12rem; column-gap: 1.5rem; margin: .5rem 0 0; }
.gl li { break-inside: avoid; margin: .25rem 0; }
.gl-n { font-size: .8rem; color: var(--ink-soft); }

footer { border-top: 1px solid var(--line); margin-top: 3rem; padding: 1.5rem 0 2.5rem; font-size: .85rem; color: var(--ink-soft); }