:root {
  --bg: #f6f4ef; --card: #ffffff; --ink: #1b2433; --muted: #59627a; --line: #e1ded6; --soft: #efece5;
  --blue: #1d3f8f; --blue-ink: #ffffff; --blue-soft: #e6ecf8; --red: #c8102e;
  --ok: #17703f; --ok-soft: #e3f3e9; --ko: #b3261e; --ko-soft: #fbe7e5; --mid: #a35f00;
  --focus: #f0b429; --shadow: 0 1px 2px rgba(20, 30, 50, .06), 0 4px 14px rgba(20, 30, 50, .05);
  color-scheme: light;
}
@media (prefers-color-scheme: dark) {
  :root:not([data-mode=light]) {
    --bg: #0f1420; --card: #182033; --ink: #e8ebf2; --muted: #a3acc0; --line: #2a3450; --soft: #1f2840;
    --blue: #8fb0ff; --blue-ink: #0f1420; --blue-soft: #24305066; --red: #ff6b7d;
    --ok: #5fd08d; --ok-soft: #173826; --ko: #ff8a80; --ko-soft: #3d1c1c; --mid: #f0b45a;
    --shadow: none; color-scheme: dark;
  }
}
:root[data-mode=dark] {
  --bg: #0f1420; --card: #182033; --ink: #e8ebf2; --muted: #a3acc0; --line: #2a3450; --soft: #1f2840;
  --blue: #8fb0ff; --blue-ink: #0f1420; --blue-soft: #24305066; --red: #ff6b7d;
  --ok: #5fd08d; --ok-soft: #173826; --ko: #ff8a80; --ko-soft: #3d1c1c; --mid: #f0b45a;
  --shadow: none; color-scheme: dark;
}

* { box-sizing: border-box; }
html { -webkit-text-size-adjust: 100%; }
html[data-text=lg] { font-size: 120%; }
body { margin: 0; background: var(--bg); color: var(--ink);
  font: 1.125rem/1.5 system-ui, -apple-system, "Segoe UI", Roboto, "Helvetica Neue", sans-serif; }
main { max-width: 760px; margin: 0 auto; padding: 8px 16px calc(64px + env(safe-area-inset-bottom)); outline: none; }
h1 { font-size: 1.75rem; line-height: 1.2; margin: 12px 0 10px; letter-spacing: -.01em; }
h2 { font-size: 1.2rem; line-height: 1.3; margin: 28px 0 12px; }
.h3 { font-size: 1.08rem; margin: 0 0 12px; }
.mt { margin-top: 20px; }
p { margin: 0 0 12px; }
.lead { font-size: 1.05rem; }
.muted { color: var(--muted); }
.small { font-size: .88rem; }
.center { text-align: center; }
a { color: var(--blue); text-underline-offset: 2px; }
button { font: inherit; color: inherit; cursor: pointer; }
:focus-visible { outline: 3px solid var(--focus); outline-offset: 2px; border-radius: 6px; }
.skip { position: absolute; left: -9999px; }
.skip:focus { left: 12px; top: 12px; background: var(--card); padding: 8px 12px; z-index: 9; }
[hidden] { display: none !important; }

.flag { display: flex; height: 5px; }
.flag i { flex: 1; } .flag i:nth-child(1) { background: #1d3f8f; } .flag i:nth-child(2) { background: #fff; } .flag i:nth-child(3) { background: #c8102e; }
.top { max-width: 760px; margin: 0 auto; padding: 10px 16px 0; display: flex; align-items: center; justify-content: space-between; }
.brand { font-weight: 700; color: var(--ink); text-decoration: none; font-size: 1rem; }
.brand span { font-weight: 400; color: var(--muted); }
.top-tools { display: flex; gap: 8px; }
.text-btn span { font-weight: 700; font-size: .8rem; line-height: 1; } .text-btn b { font-size: 1.15rem; }
.text-btn[aria-pressed=true] { background: var(--blue-soft); border-color: var(--blue); color: var(--blue); }
.icon-btn { width: 44px; height: 44px; display: grid; place-items: center; border: 1px solid var(--line);
  border-radius: 12px; background: var(--card); color: var(--ink); }

.card { background: var(--card); border: 1px solid var(--line); border-radius: 16px; padding: 18px; margin: 16px 0;
  box-shadow: var(--shadow); }

/* tracks */
.tracks { border: 0; padding: 0; margin: 18px 0; display: grid; gap: 8px; }
.tracks legend { font-weight: 600; margin-bottom: 8px; padding: 0; }
.tracks label { display: block; cursor: pointer; }
.tracks input { position: absolute; opacity: 0; }
.tracks span { display: flex; justify-content: space-between; align-items: center; gap: 12px; min-height: 56px;
  padding: 10px 16px; border: 2px solid var(--line); border-radius: 14px; background: var(--card); }
.tracks small { color: var(--muted); font-size: .85rem; text-align: right; white-space: nowrap; }
.tracks input:checked + span { border-color: var(--blue); background: var(--blue-soft); }
.tracks input:checked + span b::before { content: "✓ "; color: var(--blue); }
.tracks input:focus-visible + span { outline: 3px solid var(--focus); outline-offset: 2px; }

/* readiness */
.ready { display: flex; gap: 18px; align-items: center; }
.ready .gauge { flex: 0 0 96px; }
.ready h2 { margin-bottom: 4px; font-size: 1.25rem; }
.ready p { margin: 0 0 4px; }
.ring { width: 100%; height: auto; display: block; }
.ring circle { fill: none; stroke-width: 10; }
.ring-bg { stroke: var(--soft); }
.ring-fg { stroke: var(--blue); stroke-linecap: round; transition: stroke-dasharray .6s ease; }
.ring text { fill: var(--ink); font-size: 20px; font-weight: 700; }
.ring.big text { font-size: 19px; }

/* modes */
.modes { display: grid; gap: 10px; }
.mode { display: flex; gap: 14px; align-items: flex-start; text-align: left; width: 100%; min-height: 72px;
  padding: 16px; border: 1px solid var(--line); border-radius: 16px; background: var(--card); box-shadow: var(--shadow); }
.mode:hover { border-color: var(--blue); }
.mode .ico { font-size: 1.5rem; line-height: 1; flex: 0 0 auto; margin-top: 2px; }
.mode b { display: block; font-size: 1.05rem; }
.mode small { display: block; color: var(--muted); font-size: .9rem; margin-top: 2px; }
.mode.main { background: var(--blue); border-color: var(--blue); color: var(--blue-ink); }
.mode.main small { color: inherit; opacity: .85; }
@media (min-width: 700px) { .modes { grid-template-columns: repeat(2, 1fr); } .mode.main { grid-column: 1 / -1; } }

.theme-list { list-style: none; padding: 0; margin: 0; display: grid; gap: 8px; }
.theme-btn { display: flex; gap: 12px; align-items: center; width: 100%; text-align: left; padding: 12px;
  border: 1px solid var(--line); border-radius: 12px; background: var(--bg); min-height: 56px; }
.theme-btn:hover { border-color: var(--blue); }
.tn { flex: 0 0 34px; height: 34px; border-radius: 50%; display: grid; place-items: center; background: var(--blue-soft);
  color: var(--blue); font-weight: 700; }
.tt { flex: 1; } .tt b { display: block; } .tt small { color: var(--muted); font-size: .85rem; }
.mini { display: block; height: 5px; background: var(--soft); border-radius: 3px; margin-top: 6px; overflow: hidden; }
.mini i { display: block; height: 100%; background: var(--ok); }

/* custom mock */
.checks, .seg { border: 0; padding: 0; margin: 0 0 14px; }
.checks legend, .seg legend { font-weight: 600; padding: 0; margin-bottom: 8px; }
.checks { display: grid; gap: 8px; }
.checks label { display: flex; gap: 12px; align-items: center; min-height: 48px; padding: 8px 12px; border: 1px solid var(--line);
  border-radius: 12px; background: var(--bg); cursor: pointer; }
.checks input { width: 22px; height: 22px; flex: 0 0 22px; accent-color: var(--blue); margin: 0; }
.seg { display: flex; gap: 8px; flex-wrap: wrap; }
.seg legend { width: 100%; }
.seg label { flex: 1 1 0; cursor: pointer; }
.seg input { position: absolute; opacity: 0; }
.seg span { display: grid; place-items: center; min-height: 48px; border: 2px solid var(--line); border-radius: 12px;
  background: var(--card); font-weight: 600; }
.seg input:checked + span { border-color: var(--blue); background: var(--blue-soft); color: var(--blue); }
.seg input:focus-visible + span { outline: 3px solid var(--focus); outline-offset: 2px; }
#custom-pick .btn { width: 100%; }

/* export / import */
.data-btns { display: grid; gap: 10px; margin-bottom: 8px; }
@media (min-width: 640px) { .data-btns { grid-template-columns: 1fr 1fr; } }
#data-msg:empty { display: none; }
#data-msg.ko { color: var(--ko); } #data-msg.ok { color: var(--ok); }

/* diagnostic */
.diag { border-top: 5px solid var(--blue); }
.diag .btn { width: 100%; margin-bottom: 8px; }
.diag .link { display: block; margin: 4px auto 0; min-height: 44px; }
.verdict { flex-wrap: wrap; }
.verdict-cta { flex: 1 1 100%; }
.verdict-cta p { margin: 4px 0 10px; }
.verdict-cta .btn { width: 100%; }

/* exam-date plan */
.plan .countdown { display: inline-block; font-variant-numeric: tabular-nums; background: var(--blue); color: var(--blue-ink);
  border-radius: 10px; padding: 2px 10px; margin-right: 6px; }
.plan-date { display: flex; flex-wrap: wrap; align-items: center; gap: 8px 12px; margin-bottom: 4px; }
.plan-date label { font-weight: 600; }
.plan-date input { font: inherit; min-height: 44px; padding: 6px 10px; border: 1px solid var(--line); border-radius: 10px;
  background: var(--bg); color: var(--ink); }
.plan-steps { list-style: none; padding: 0; margin: 14px 0; display: grid; gap: 8px; }
.plan-steps li { display: flex; gap: 10px; align-items: flex-start; padding: 10px 12px; border-radius: 12px; background: var(--bg); }
.plan-steps li::before { content: ""; flex: 0 0 22px; height: 22px; border-radius: 50%; border: 2px solid var(--line); margin-top: 2px; }
.plan-steps li.done::before { content: "✓"; border-color: var(--ok); background: var(--ok); color: var(--card);
  display: grid; place-items: center; font-size: .8rem; font-weight: 700; }
.plan-steps small { display: block; color: var(--muted); font-size: .85rem; }
.plan .btn { width: 100%; }

/* book block */
.book { border-left: 4px solid var(--blue); }
.ticks { padding-left: 0; list-style: none; margin: 0 0 14px; }
.ticks li { padding-left: 26px; position: relative; margin: 6px 0; }
.ticks li::before { content: "✓"; position: absolute; left: 2px; color: var(--ok); font-weight: 700; }

/* buttons */
.btn { display: inline-flex; align-items: center; justify-content: center; min-height: 50px; padding: 10px 18px;
  border-radius: 12px; border: 2px solid var(--blue); font-weight: 600; text-decoration: none; text-align: center; }
.btn.primary { background: var(--blue); color: var(--blue-ink); }
.btn.primary:disabled { opacity: .45; cursor: default; }
.btn.ghost { background: transparent; color: var(--blue); }
.btn.ghost:disabled { opacity: .4; cursor: default; }
.btn.small { min-height: 40px; padding: 6px 12px; font-size: .9rem; margin-top: 6px; }
.link { background: none; border: 0; padding: 0; color: var(--blue); text-decoration: underline; font-size: inherit; }
.foot { margin-top: 28px; }

/* quiz */
.qbar { display: flex; align-items: center; justify-content: space-between; gap: 10px; margin-top: 6px; }
.count { font-weight: 600; }
.timer { font-variant-numeric: tabular-nums; font-weight: 700; padding: 6px 12px; border-radius: 10px; background: var(--card);
  border: 1px solid var(--line); min-width: 76px; text-align: center; }
.timer.low { color: var(--ko); border-color: var(--ko); }
.progress { height: 6px; background: var(--soft); border-radius: 3px; margin: 12px 0 18px; overflow: hidden; }
#progress { height: 100%; background: var(--blue); width: 0; transition: width .25s; }
.eyebrow { color: var(--muted); font-size: .82rem; text-transform: uppercase; letter-spacing: .04em; margin: 0 0 8px; }
.scenario { background: var(--card); border: 1px solid var(--line); border-left: 4px solid var(--blue); padding: 14px 16px;
  border-radius: 12px; }
.scenario:empty { display: none; }
.question { font-size: 1.25rem; line-height: 1.35; margin: 8px 0 16px; outline: none; }
.qtools { display: flex; flex-wrap: wrap; gap: 8px; margin: -6px 0 14px; }
.qtools:not(:has(> :not([hidden]))) { display: none; }
.chip { display: inline-flex; align-items: center; gap: 6px; min-height: 44px; padding: 6px 14px; border-radius: 22px;
  border: 1px solid var(--line); background: var(--card); color: var(--blue); font-weight: 600; font-size: .92rem; }
.chip:hover { border-color: var(--blue); }
.chip[aria-pressed=true] { background: var(--blue-soft); border-color: var(--blue); }
.feedback .chip { margin-top: 4px; }
.gloss { color: var(--muted); font-size: .92rem; font-style: italic; border-left: 3px solid var(--line); padding-left: 10px; }
.question + .gloss { margin: -8px 0 14px; }
.options { display: grid; gap: 10px; }
.opt { display: flex; gap: 12px; align-items: flex-start; width: 100%; text-align: left; min-height: 56px; padding: 12px 14px;
  border: 2px solid var(--line); border-radius: 14px; background: var(--card); color: var(--ink); }
.opt:hover:not(:disabled) { border-color: var(--muted); }
.opt .key { flex: 0 0 30px; height: 30px; border-radius: 8px; display: grid; place-items: center; background: var(--soft);
  font-weight: 700; font-size: .9rem; }
.opt .txt { padding-top: 2px; }
.opt[aria-checked=true] { border-color: var(--blue); background: var(--blue-soft); }
.opt[aria-checked=true] .key { background: var(--blue); color: var(--blue-ink); }
.opt.right { border-color: var(--ok); background: var(--ok-soft); }
.opt.right .key { background: var(--ok); color: var(--card); }
.opt.wrong { border-color: var(--ko); background: var(--ko-soft); }
.opt.wrong .key { background: var(--ko); color: var(--card); }
.opt:disabled { cursor: default; color: var(--ink); }
.feedback { margin-top: 16px; padding: 14px 16px; border-radius: 14px; border: 1px solid var(--line); background: var(--card); }
.feedback.ok { border-left: 5px solid var(--ok); }
.feedback.ko { border-left: 5px solid var(--ko); }
.fb-h { font-weight: 700; }
.feedback.ok .fb-h { color: var(--ok); } .feedback.ko .fb-h { color: var(--ko); }
.fb-a { font-weight: 600; }
.chap { color: var(--blue); font-weight: 600; margin-bottom: 0; }
.qactions { display: grid; grid-template-columns: 1fr 2fr; gap: 10px; margin: 20px 0 10px;
  position: sticky; bottom: 0; padding: 10px 0 calc(10px + env(safe-area-inset-bottom)); background: var(--bg);
  box-shadow: 0 -10px 12px -8px var(--bg); }
.qactions #skip[hidden] + #next { grid-column: 1 / -1; }

/* result */
.verdict { display: flex; gap: 18px; align-items: center; }
.verdict .score-ring { flex: 0 0 110px; }
.verdict h1 { margin: 0 0 4px; font-size: 2rem; }
.verdict p { margin: 0 0 4px; }
.verdict.pass { border-top: 5px solid var(--ok); } .verdict.pass h1 { color: var(--ok); } .verdict.pass .ring-fg { stroke: var(--ok); }
.verdict.fail { border-top: 5px solid var(--ko); } .verdict.fail h1 { color: var(--ko); } .verdict.fail .ring-fg { stroke: var(--ko); }
.verdict.practice { border-top: 5px solid var(--blue); }
.grid2 { display: grid; gap: 0 16px; }
@media (min-width: 700px) { .grid2 { grid-template-columns: 1fr 1fr; } }
.bars { list-style: none; padding: 0; margin: 0; }
.bars li { margin: 0 0 14px; }
.bar-h { display: flex; justify-content: space-between; gap: 8px; font-size: .95rem; margin-bottom: 4px; }
.bar-t { position: relative; height: 10px; background: var(--soft); border-radius: 5px; overflow: hidden; }
.bar-t div { height: 100%; border-radius: 5px; background: var(--blue); }
.bar-t i { position: absolute; top: 0; bottom: 0; width: 2px; background: var(--muted); opacity: .5; }
.bars .good .bar-t div { background: var(--ok); } .bars .mid .bar-t div { background: var(--mid); } .bars .low .bar-t div { background: var(--ko); }
.weak { list-style: none; padding: 0; margin: 0; }
.weak li { padding: 12px 0; border-top: 1px solid var(--line); }
.weak li:first-child { border-top: 0; padding-top: 0; }
.weak .chap { margin: 4px 0 0; font-weight: 500; }
.chart { width: 100%; max-width: 560px; height: auto; display: block; margin: 0 auto; }
.chart text { fill: var(--muted); font-size: 11px; }
.chart .grid { stroke: var(--line); }
.chart .pass { stroke: var(--ok); stroke-dasharray: 4 3; }
.chart .pass-t { fill: var(--ok); }
.chart .line { fill: none; stroke: var(--blue); stroke-width: 2.5; }
.chart .dot { stroke: var(--card); stroke-width: 2; } .chart .dot.ok { fill: var(--ok); } .chart .dot.ko { fill: var(--ko); }
.actions { display: grid; gap: 10px; margin: 20px 0; }
@media (min-width: 640px) { .actions { grid-template-columns: 1fr 1fr; } }
.corr summary { cursor: pointer; list-style: none; }
.corr summary::-webkit-details-marker { display: none; }
.corr summary h2 { display: inline; margin: 0; }
.corr summary::after { content: " ▾"; color: var(--muted); }
.corr[open] summary::after { content: " ▴"; }
.review { padding-left: 22px; margin: 16px 0 0; }
.review li { margin: 0 0 18px; }
.review .q { font-weight: 600; margin-bottom: 4px; }
.review .ans { margin-bottom: 2px; }
.review li.ok .ans { color: var(--ok); }
.review li.ko .ans { color: var(--ko); }
.review .ans.good { color: var(--ok); }
.review .why { margin: 6px 0 4px; }

/* errata page */
main > ul { padding-left: 22px; }

@media (prefers-reduced-motion: reduce) { * { transition: none !important; scroll-behavior: auto !important; } }
@media (max-width: 380px) { body { font-size: 1.0625rem; } h1 { font-size: 1.55rem; } .ready .gauge { flex-basis: 80px; } .verdict .score-ring { flex-basis: 92px; } }