/* Layout: one reading column (max ~72ch for lessons) inside a 1120px frame; sticky top bar; cards only for interactive units. */
:root {
  --bg: #f5f7f9;
  --surface: #ffffff;
  --sunk: #eef2f5;
  --ink: #142033;
  --muted: #5b6678;
  --line: #dde3ea;
  --navy: #0b2545;
  --accent: #0f766e;
  --accent-ink: #ffffff;
  --gold: #a87a1f;
  --gold-wash: #fbf4e4;
  --ok: #157f4a;
  --ok-wash: #e6f5ec;
  --bad: #b42318;
  --bad-wash: #fdecea;
  --tip-wash: #fff6dd;
  --display: "Source Serif 4", Georgia, "Times New Roman", serif;
  --body: "Inter", system-ui, -apple-system, "Segoe UI", Roboto, sans-serif;
  --r: 12px;
}
@media (prefers-color-scheme: dark) {
  :root:not([data-theme="light"]) {
    --bg: #0e1522; --surface: #151e2e; --sunk: #1b2639; --ink: #e7ecf4; --muted: #9ba7b9; --line: #283449;
    --navy: #cfe0ff; --accent: #2dd4bf; --accent-ink: #04201d; --gold: #e2b65c; --gold-wash: #2a2312;
    --ok: #4ade80; --ok-wash: #12301f; --bad: #f87171; --bad-wash: #3a1717; --tip-wash: #2d2610; color-scheme: dark;
  }
}
:root[data-theme="dark"] {
  --bg: #0e1522; --surface: #151e2e; --sunk: #1b2639; --ink: #e7ecf4; --muted: #9ba7b9; --line: #283449;
  --navy: #cfe0ff; --accent: #2dd4bf; --accent-ink: #04201d; --gold: #e2b65c; --gold-wash: #2a2312;
  --ok: #4ade80; --ok-wash: #12301f; --bad: #f87171; --bad-wash: #3a1717; --tip-wash: #2d2610; color-scheme: dark;
}
* { box-sizing: border-box; }
body { background: var(--bg); color: var(--ink); font: 16px/1.6 var(--body); margin: 0; }
a { color: var(--accent); }
a:focus-visible, button:focus-visible, select:focus-visible, input:focus-visible, textarea:focus-visible { outline: 2px solid var(--accent); outline-offset: 2px; }
h1, h2, h3 { font-family: var(--display); line-height: 1.2; margin: 0 0 .5em; text-wrap: balance; color: var(--ink); }
h1 { font-size: clamp(1.8rem, 4vw, 2.6rem); }
h2 { font-size: clamp(1.35rem, 2.6vw, 1.75rem); }
h3 { font-size: 1.15rem; }
p { margin: 0 0 1em; }
.wrap { max-width: 1120px; margin: 0 auto; padding-inline: 16px; padding-block: 24px; }
.read { max-width: 74ch; }
.muted { color: var(--muted); }
.fine { font-size: .82rem; color: var(--muted); }
.eyebrow { font-size: .75rem; letter-spacing: .09em; text-transform: uppercase; font-weight: 700; color: var(--accent); margin-bottom: 6px; }
.loading { color: var(--muted); padding: 40px 0; }
.stack { display: grid; gap: 16px; }
.row { display: flex; flex-wrap: wrap; gap: 12px; align-items: center; }
.between { justify-content: space-between; }
.grid { display: grid; gap: 16px; grid-template-columns: repeat(auto-fit, minmax(250px, 1fr)); }
.grid > * { min-width: 0; }

/* top bar */
.top { position: sticky; top: env(safe-area-inset-top, 0px); z-index: 20; background: var(--surface); border-bottom: 1px solid var(--line); }
.top-in { max-width: 1120px; margin: 0 auto; padding-inline: 16px; display: flex; align-items: center; gap: 20px; min-height: 58px; flex-wrap: wrap; }
.brand { display: flex; align-items: center; gap: 10px; font-weight: 700; color: var(--ink); text-decoration: none; font-size: 1.05rem; }
.mark { width: 30px; height: 30px; border-radius: 7px; background: var(--navy); color: var(--bg); display: grid; place-items: center; font-family: var(--display); font-weight: 700; font-size: .8rem; letter-spacing: .02em; }
.nav { display: flex; gap: 2px; flex-wrap: wrap; overflow-x: auto; }
.nav a { color: var(--muted); text-decoration: none; padding: 7px 11px; border-radius: 8px; font-size: .92rem; font-weight: 500; white-space: nowrap; }
.nav a:hover, .nav a.on { background: var(--sunk); color: var(--ink); }
@media (max-width: 720px) { .top-in { padding-block: 8px; gap: 8px; } .nav { width: 100%; flex-wrap: nowrap; } }

/* buttons, badges */
.btn { display: inline-flex; align-items: center; justify-content: center; gap: 8px; padding: 10px 16px; border-radius: 10px; border: 1px solid var(--line); background: var(--surface); color: var(--ink); font: 600 .93rem var(--body); cursor: pointer; text-decoration: none; }
.btn:hover { border-color: var(--muted); }
.btn:disabled { opacity: .5; cursor: not-allowed; }
.btn.primary { background: var(--accent); border-color: var(--accent); color: var(--accent-ink); }
.btn.big { padding: 13px 22px; font-size: 1rem; }
.btn.small { padding: 6px 11px; font-size: .84rem; }
.link { background: none; border: 0; padding: 0; color: var(--accent); font: inherit; cursor: pointer; text-decoration: underline; }
.badge { display: inline-block; padding: 2px 9px; border-radius: 999px; background: var(--sunk); color: var(--muted); font-size: .75rem; font-weight: 600; white-space: nowrap; }
.badge.ok { background: var(--ok-wash); color: var(--ok); }
.badge.bad { background: var(--bad-wash); color: var(--bad); }
.badge.gold { background: var(--gold-wash); color: var(--gold); }

/* cards and panels */
.card { background: var(--surface); border: 1px solid var(--line); border-radius: var(--r); padding: 20px; }
a.card { color: inherit; text-decoration: none; display: block; }
a.card:hover { border-color: var(--accent); }
.bar { height: 7px; background: var(--sunk); border-radius: 99px; overflow: hidden; }
.bar > i { display: block; height: 100%; background: var(--accent); }
.stat b { display: block; font: 700 1.7rem/1.1 var(--display); font-variant-numeric: tabular-nums; }
.stat span { color: var(--muted); font-size: .85rem; }

/* home */
.hero { display: grid; grid-template-columns: 1.15fr .85fr; gap: 32px; align-items: center; padding-block: 24px 8px; }
.hero > * { min-width: 0; }
.hero p.lead { font-size: 1.12rem; color: var(--muted); max-width: 58ch; }
@media (max-width: 860px) { .hero { grid-template-columns: 1fr; } }
.ledger { background: var(--surface); border: 1px solid var(--line); border-radius: var(--r); padding: 18px 20px; font-variant-numeric: tabular-nums; }
.ledger table { width: 100%; border-collapse: collapse; font-size: .92rem; }
.ledger td { padding: 7px 0; border-bottom: 1px dashed var(--line); }
.ledger td:last-child { text-align: right; font-weight: 600; }
.ledger tr:last-child td { border-bottom: 0; }

/* lists of modules */
.mods { display: grid; }
.mod { display: grid; grid-template-columns: 44px 1fr auto; gap: 12px; padding: 14px 0; border-bottom: 1px solid var(--line); align-items: start; }
.mod:last-child { border-bottom: 0; }
.mod > * { min-width: 0; }
.mod .n { font: 700 1rem var(--display); color: var(--muted); font-variant-numeric: tabular-nums; }
.mod ul { margin: 6px 0 0; padding-left: 1.1em; color: var(--muted); font-size: .9rem; }
.mod details summary { cursor: pointer; color: var(--muted); font-size: .85rem; margin-top: 4px; }

/* lesson */
.lesson { display: grid; grid-template-columns: 250px 1fr; gap: 32px; align-items: start; }
.lesson > * { min-width: 0; }
@media (max-width: 900px) { .lesson { grid-template-columns: 1fr; } .side { order: 2; } }
.side { position: sticky; top: calc(env(safe-area-inset-top, 0px) + 74px); }
.steps { list-style: none; margin: 10px 0 0; padding: 0; font-size: .9rem; }
.steps a { display: grid; grid-template-columns: 24px 1fr; gap: 8px; padding: 7px 8px; border-radius: 8px; color: var(--muted); text-decoration: none; }
.steps a:hover { background: var(--sunk); }
.steps li.cur a { background: var(--sunk); color: var(--ink); font-weight: 600; }
.dot { width: 22px; height: 22px; border-radius: 50%; border: 2px solid var(--line); display: grid; place-items: center; font-size: .7rem; font-weight: 700; }
.steps li.done .dot { background: var(--accent); border-color: var(--accent); color: var(--accent-ink); }
.crumb { font-size: .86rem; color: var(--muted); margin-bottom: 10px; }
.crumb a { color: var(--muted); }
.statement { border-left: 4px solid var(--accent); background: var(--surface); padding: 14px 18px; border-radius: 0 10px 10px 0; margin: 12px 0 24px; }
.prose { font-size: 1.02rem; }
.prose table { border-collapse: collapse; margin: 10px 0 16px; font-size: .92rem; display: block; overflow-x: auto; max-width: 100%; }
.prose th, .prose td { border: 1px solid var(--line); padding: 6px 10px; text-align: left; }
.prose th { background: var(--sunk); }
.label { font-size: .75rem; letter-spacing: .09em; text-transform: uppercase; font-weight: 700; color: var(--muted); margin: 28px 0 10px; }
.points { background: var(--surface); border: 1px solid var(--line); border-radius: var(--r); padding: 14px 20px; }
.points ul { margin: 0; padding-left: 1.1em; }
.points li + li { margin-top: 5px; }
.formula { background: var(--surface); border: 1px solid var(--line); border-radius: var(--r); padding: 12px 18px; margin-bottom: 10px; overflow-x: auto; }
.formula .fn { font-weight: 600; font-size: .9rem; }
.formula .fw { color: var(--muted); font-size: .86rem; }
.example { background: var(--surface); border: 1px solid var(--line); border-radius: var(--r); padding: 18px 20px; }
.example details { border-top: 1px dashed var(--line); margin-top: 12px; padding-top: 10px; }
.example summary { cursor: pointer; color: var(--accent); font-weight: 600; }
.market { background: var(--gold-wash); border: 1px solid var(--gold); border-radius: var(--r); padding: 18px 20px; }
.market .tag { color: var(--gold); }
.market .lesson-line { font-weight: 600; margin: 10px 0 0; }
.tip { background: var(--tip-wash); border-radius: var(--r); padding: 12px 18px; }
.pager { display: flex; justify-content: space-between; gap: 12px; flex-wrap: wrap; margin: 36px 0 8px; }
mjx-container { max-width: 100%; overflow-x: auto; overflow-y: hidden; }

/* questions */
.q { background: var(--surface); border: 1px solid var(--line); border-radius: var(--r); padding: 18px 20px; margin-bottom: 16px; }
.q-head { display: flex; gap: 6px; flex-wrap: wrap; align-items: center; font-size: .84rem; color: var(--muted); margin-bottom: 8px; }
.q-head b { color: var(--ink); margin-right: 4px; }
.opts { display: grid; gap: 8px; margin-top: 10px; }
.opt { display: grid; grid-template-columns: 30px 1fr; gap: 10px; text-align: left; padding: 11px 13px; border: 1.5px solid var(--line); border-radius: 10px; background: var(--surface); color: var(--ink); font: inherit; cursor: pointer; width: 100%; }
.opt > * { min-width: 0; }
.opt:hover:not(:disabled) { border-color: var(--accent); }
.opt .L { width: 26px; height: 26px; border-radius: 50%; background: var(--sunk); display: grid; place-items: center; font-weight: 700; font-size: .82rem; }
.opt.sel { border-color: var(--accent); }
.opt.sel .L { background: var(--accent); color: var(--accent-ink); }
.opt.right { border-color: var(--ok); background: var(--ok-wash); }
.opt.right .L { background: var(--ok); color: var(--surface); }
.opt.wrong { border-color: var(--bad); background: var(--bad-wash); }
.opt.wrong .L { background: var(--bad); color: var(--surface); }
.opt:disabled { cursor: default; }
.opt .why { grid-column: 2; font-size: .87rem; color: var(--muted); }
.opt .why:empty { display: none; }
.fb { margin-top: 14px; padding: 12px 16px; border-radius: 10px; background: var(--sunk); }
.fb .v { font-weight: 700; margin-bottom: 4px; }
.fb.ok .v { color: var(--ok); }
.fb.bad .v { color: var(--bad); }
.qa { display: flex; gap: 14px; align-items: center; margin-top: 12px; flex-wrap: wrap; }
.vignette { background: var(--surface); border: 1px solid var(--line); border-radius: var(--r); padding: 18px 20px; margin-bottom: 16px; }
.essay-part { border-top: 1px solid var(--line); padding-top: 14px; margin-top: 14px; }
textarea, select, input { width: 100%; padding: 10px 12px; border-radius: 10px; border: 1px solid var(--line); background: var(--surface); color: var(--ink); font: inherit; }
.check { display: flex; gap: 8px; align-items: center; font-size: .92rem; }
.check input { width: auto; }
.form-grid { display: grid; gap: 14px; grid-template-columns: repeat(auto-fit, minmax(180px, 1fr)); }
.form-grid > * { min-width: 0; }
label.f { display: block; font-weight: 600; font-size: .86rem; margin-bottom: 5px; }

/* exam */
.exam-top { position: sticky; top: calc(env(safe-area-inset-top, 0px) + 58px); z-index: 10; background: var(--navy); color: var(--bg); border-radius: 10px; padding: 10px 14px; display: flex; gap: 12px; align-items: center; flex-wrap: wrap; margin-bottom: 18px; }
.exam-top .t { flex: 1; font-weight: 600; min-width: 0; overflow: hidden; text-overflow: ellipsis; white-space: nowrap; }
.timer { font-variant-numeric: tabular-nums; font-weight: 700; padding: 4px 10px; border-radius: 7px; background: var(--accent); color: var(--accent-ink); }
.timer.low { background: var(--bad); color: var(--surface); }
.exam { display: grid; grid-template-columns: 1fr 240px; gap: 20px; align-items: start; }
.exam > * { min-width: 0; }
@media (max-width: 900px) { .exam { grid-template-columns: 1fr; } }
.navg { display: grid; grid-template-columns: repeat(6, 1fr); gap: 5px; max-height: 50vh; overflow-y: auto; }
.navg button { padding: 5px 0; border: 1px solid var(--line); border-radius: 6px; background: var(--surface); color: var(--ink); font: .78rem var(--body); cursor: pointer; font-variant-numeric: tabular-nums; }
.navg button.a { background: var(--accent); border-color: var(--accent); color: var(--accent-ink); }
.navg button.f { box-shadow: inset 0 -3px 0 var(--gold); }
.navg button.c { outline: 2px solid var(--ink); }
.confirm { border: 2px solid var(--accent); }

/* tables */
.tbl { overflow-x: auto; }
table.t { width: 100%; border-collapse: collapse; font-size: .92rem; font-variant-numeric: tabular-nums; }
table.t th, table.t td { text-align: left; padding: 9px 10px; border-bottom: 1px solid var(--line); vertical-align: top; }
table.t th { font-size: .74rem; text-transform: uppercase; letter-spacing: .06em; color: var(--muted); }

.foot { border-top: 1px solid var(--line); background: var(--surface); margin-top: 48px; font-size: .9rem; }
@media (prefers-reduced-motion: reduce) { * { scroll-behavior: auto !important; transition: none !important; } }
.select { user-select: all; -webkit-user-select: all; font-weight: 600; }
.email { font-size: 1.15rem; word-break: break-all; }
.seo-links { font-size: .85rem; color: var(--muted); }
.seo-links a { color: var(--muted); }

.page-top{background:var(--surface);border-bottom:1px solid var(--line)}
.page-top .in{max-width:1120px;margin:0 auto;padding:12px 16px;display:flex;gap:18px;align-items:center;flex-wrap:wrap}
.page-top nav{display:flex;gap:14px;flex-wrap:wrap;font-size:.92rem}
.page-top nav a{color:var(--muted);text-decoration:none}
.cta{display:flex;gap:12px;flex-wrap:wrap;margin:20px 0}
.outcome h3{margin-top:22px}