:root {
  --bg: #f6f3ec;
  --panel: #ffffff;
  --panel-2: #faf8f3;
  --ink: #1f2a26;
  --ink-2: #4b5852;
  --muted: #7b867f;
  --line: #e4dfd2;
  --accent: #2c6e5b;
  --accent-ink: #ffffff;
  --accent-soft: #e2f0ea;
  --ok: #1f8a4c;
  --ok-soft: #e1f3e8;
  --bad: #c0392b;
  --bad-soft: #fbe6e3;
  --hl: #fff1a6;
  --hl-o: #ffd9b3;
  --shadow: 0 1px 2px rgba(30, 40, 35, .06), 0 4px 16px rgba(30, 40, 35, .05);
  --serif: "Source Serif 4", "Noto Serif KR", Georgia, "Times New Roman", serif;
  --sans: "Pretendard", "Segoe UI", "Malgun Gothic", "Apple SD Gothic Neo", system-ui, sans-serif;
  --side-w: 300px;
}
@media (prefers-color-scheme: dark) {
  :root {
    --bg: #14181a;
    --panel: #1c2225;
    --panel-2: #20282b;
    --ink: #e8ece9;
    --ink-2: #b4beb8;
    --muted: #8a968f;
    --line: #2d3734;
    --accent: #5cc2a1;
    --accent-ink: #0d1a15;
    --accent-soft: #1d3a31;
    --ok: #55d08a;
    --ok-soft: #1a3a28;
    --bad: #ff8a7a;
    --bad-soft: #3e2220;
    --hl: #5b5420;
    --hl-o: #6a4524;
    --shadow: 0 1px 2px rgba(0,0,0,.3), 0 4px 16px rgba(0,0,0,.25);
  }
}

* { box-sizing: border-box; }
html, body { margin: 0; height: 100%; }
body {
  background: var(--bg);
  color: var(--ink);
  font-family: var(--sans);
  font-size: 16px;
  line-height: 1.6;
  -webkit-font-smoothing: antialiased;
}
button { font: inherit; color: inherit; cursor: pointer; }
a { color: var(--accent); }
a.tile, a.btn, a.rail-chip, a.nav-item { text-decoration: none; color: inherit; }
a.btn.primary { color: var(--accent-ink); }
a.rail-chip.cur { color: var(--accent-ink); }
a.rail-chip.done { color: var(--ok); }
a.rail-chip.cur.done { color: var(--accent-ink); }

.app { display: flex; min-height: 100vh; }

/* ───────── sidebar ───────── */
.side {
  width: var(--side-w);
  flex: none;
  position: sticky;
  top: 0;
  height: 100vh;
  overflow-y: auto;
  background: var(--panel);
  border-right: 1px solid var(--line);
  padding: 18px 14px 28px;
}
.brand { padding: 4px 8px 14px; }
.brand h1 { margin: 0; font-size: 18px; letter-spacing: -.01em; }
.brand p { margin: 2px 0 10px; color: var(--muted); font-size: 13px; }
.total-bar { height: 6px; background: var(--line); border-radius: 99px; overflow: hidden; }
.total-bar span { display: block; height: 100%; background: var(--accent); border-radius: 99px; transition: width .3s; }
.total-txt { font-size: 12px; color: var(--muted); margin-top: 6px; }

.nav-list { list-style: none; margin: 8px 0 0; padding: 0; }
.nav-item {
  display: flex; align-items: center; gap: 10px;
  width: 100%;
  padding: 9px 10px;
  border: 0; background: transparent;
  border-radius: 10px;
  text-align: left;
  color: var(--ink);
  text-decoration: none;
}
.nav-item:hover { background: var(--panel-2); }
.nav-item.active { background: var(--accent-soft); }
.nav-badge {
  flex: none;
  width: 34px; height: 34px;
  display: grid; place-items: center;
  border-radius: 10px;
  background: var(--panel-2);
  border: 1px solid var(--line);
  font-weight: 700; font-size: 13px;
  color: var(--accent);
}
.nav-item.active .nav-badge { background: var(--accent); color: var(--accent-ink); border-color: var(--accent); }
.nav-txt { min-width: 0; flex: 1; }
.nav-txt b { display: block; font-size: 14px; line-height: 1.25; font-weight: 600; }
.nav-txt small { display: block; color: var(--muted); font-size: 12px; white-space: nowrap; overflow: hidden; text-overflow: ellipsis; }
.nav-prog { font-size: 11px; color: var(--muted); font-variant-numeric: tabular-nums; }
.nav-item.done .nav-prog { color: var(--ok); font-weight: 700; }
.nav-sep { margin: 12px 8px 4px; font-size: 11px; letter-spacing: .08em; color: var(--muted); text-transform: uppercase; }
.pill-count { background: var(--bad); color: #fff; border-radius: 99px; padding: 0 7px; font-size: 11px; font-weight: 700; line-height: 18px; }

/* ───────── main ───────── */
.main { flex: 1; min-width: 0; padding: 28px clamp(16px, 4vw, 48px) 80px; outline: none; }
.wrap { max-width: 860px; margin: 0 auto; }

h2.ch-title { margin: 0; font-size: clamp(22px, 3.2vw, 30px); letter-spacing: -.02em; line-height: 1.25; }
.ch-sub { color: var(--ink-2); margin: 4px 0 0; }
.ch-no { display: block; font-size: 12px; font-weight: 700; letter-spacing: .08em; color: var(--accent); text-transform: uppercase; margin-bottom: 4px; }

.rail { display: flex; flex-wrap: wrap; gap: 6px; margin: 18px 0 22px; padding: 10px; background: var(--panel); border: 1px solid var(--line); border-radius: 14px; }
.rail-chip {
  display: inline-flex; align-items: center; gap: 6px;
  padding: 6px 11px;
  border-radius: 99px;
  border: 1px solid var(--line);
  background: var(--panel-2);
  font-size: 13px;
  color: var(--ink-2);
  white-space: nowrap;
}
.rail-chip:hover { border-color: var(--accent); }
.rail-chip.quiz { font-weight: 600; }
.rail-chip.quiz::before { content: "✎"; font-size: 12px; }
.rail-chip.done { color: var(--ok); border-color: color-mix(in srgb, var(--ok) 40%, var(--line)); }
.rail-chip.done::after { content: "✓"; font-weight: 800; }
.rail-chip.cur { background: var(--accent); color: var(--accent-ink); border-color: var(--accent); }
.rail-chip.cur::after { color: var(--accent-ink); }

.card { background: var(--panel); border: 1px solid var(--line); border-radius: 16px; padding: clamp(16px, 3vw, 28px); box-shadow: var(--shadow); }
.part-title { margin: 0 0 6px; font-size: clamp(19px, 2.6vw, 24px); letter-spacing: -.01em; line-height: 1.3; }
.page-ref { font-size: 12px; color: var(--muted); margin-bottom: 14px; }

.tldr { background: var(--accent-soft); border-radius: 12px; padding: 10px 14px; margin: 12px 0 18px; font-size: 15px; }
.tldr b { color: var(--accent); margin-right: 6px; }

/* ───────── content blocks ───────── */
.content p { margin: 0 0 12px; font-family: var(--serif); font-size: 17px; line-height: 1.7; }
.content h3 { margin: 24px 0 8px; font-size: 17px; font-family: var(--sans); color: var(--accent); }
.content h4 { margin: 16px 0 6px; font-size: 15px; font-family: var(--sans); color: var(--ink-2); }
.content ul, .content ol { font-family: var(--serif); font-size: 17px; line-height: 1.65; margin: 0 0 12px; padding-left: 22px; }
.content li { margin: 3px 0; }
.content mark { background: var(--hl); color: inherit; padding: 0 2px; border-radius: 3px; }
.content mark.o { background: var(--hl-o); }
.content u { text-decoration-thickness: 1.5px; text-underline-offset: 3px; }
.content s { text-decoration-thickness: 1.5px; opacity: .8; }
.content .circ { border: 1.5px solid var(--ink-2); border-radius: 99px; padding: 0 5px; }
.content .bx { border: 1.5px solid var(--ink-2); border-radius: 4px; padding: 0 4px; }
.content .tag { font-family: var(--sans); font-size: 11px; font-weight: 700; padding: 1px 7px; border-radius: 99px; background: var(--panel-2); border: 1px solid var(--line); color: var(--ink-2); white-space: nowrap; }
.content .tag.ok { color: var(--ok); background: var(--ok-soft); border-color: transparent; }
.content .tag.err { color: var(--bad); background: var(--bad-soft); border-color: transparent; }
.content .sm { font-size: 14px; color: var(--ink-2); }

.ex { display: flex; gap: 12px; margin: 10px 0 14px; padding: 10px 14px; background: var(--panel-2); border: 1px solid var(--line); border-left: 4px solid var(--accent); border-radius: 10px; }
.ex-label { flex: none; font-family: var(--sans); font-size: 12px; font-weight: 800; color: var(--accent); padding-top: 4px; min-width: 34px; }
.ex-lines { flex: 1; min-width: 0; }
.ex-line { display: flex; justify-content: space-between; gap: 10px; align-items: baseline; font-family: var(--serif); font-size: 17px; line-height: 1.6; padding: 2px 0; }
.ex-line .tag { flex: 0 1 40%; white-space: normal; border-radius: 10px; font-weight: 600; line-height: 1.4; padding: 3px 9px; }
.ex-line > span:first-child { min-width: 0; }

.callout { margin: 14px 0; padding: 11px 15px; border-radius: 12px; font-family: var(--serif); font-size: 16.5px; line-height: 1.65; background: var(--panel-2); border: 1px solid var(--line); }
.callout.warn { background: var(--bad-soft); border-color: transparent; }
.callout.tip { background: var(--accent-soft); border-color: transparent; }
.callout.rule { background: var(--hl); border-color: transparent; }
.callout .callout-t { display: block; font-family: var(--sans); font-size: 12px; font-weight: 800; letter-spacing: .06em; text-transform: uppercase; margin-bottom: 3px; opacity: .75; }

.rulebox { margin: 14px 0; padding: 12px 16px; border: 2px solid var(--ink-2); border-radius: 10px; font-family: var(--serif); font-size: 16.5px; }
.rulebox > :last-child { margin-bottom: 0; }

.wordgrid { margin: 10px 0 16px; }
.wordgrid .wg-title { font-family: var(--sans); font-size: 13px; font-weight: 700; color: var(--ink-2); margin-bottom: 6px; }
.wordgrid .wg-cols { display: grid; grid-template-columns: repeat(auto-fill, minmax(190px, 1fr)); gap: 3px 18px; font-family: var(--serif); font-size: 16.5px; }
.wordgrid .wg-cols div { padding: 1px 0; border-bottom: 1px dotted var(--line); }
.wordgrid .wg-cols div.hl { background: var(--hl); border-radius: 3px; }

.tbl-wrap { overflow-x: auto; margin: 12px 0 16px; }
table.tbl { border-collapse: collapse; width: 100%; font-family: var(--serif); font-size: 16px; }
.tbl th, .tbl td { border: 1px solid var(--line); padding: 7px 11px; text-align: left; vertical-align: top; }
.tbl th { background: var(--panel-2); font-family: var(--sans); font-size: 13px; }
.tbl td.hl { background: var(--hl); }

.tree { margin: 14px 0 18px; font-family: var(--sans); font-size: 14.5px; }
.tree-title { font-weight: 700; margin-bottom: 8px; color: var(--ink-2); }
.tnode { margin: 6px 0; }
.tq { display: inline-block; padding: 7px 12px; background: var(--panel-2); border: 1.5px solid var(--ink-2); border-radius: 9px; max-width: 100%; }
.tq i { color: var(--muted); }
.tres { display: inline-block; padding: 7px 12px; border-radius: 9px; background: var(--accent-soft); border: 1.5px solid var(--accent); max-width: 100%; }
.tres.bad { background: var(--bad-soft); border-color: var(--bad); }
.tres.good { background: var(--ok-soft); border-color: var(--ok); }
.tbranches { margin: 4px 0 0 14px; padding-left: 14px; border-left: 2px solid var(--line); }
.tbr { margin: 6px 0; display: flex; gap: 8px; align-items: flex-start; }
.tlabel { flex: none; font-size: 11px; font-weight: 800; letter-spacing: .04em; padding: 1px 8px; border-radius: 99px; background: var(--ink-2); color: var(--panel); margin-top: 8px; }
.tlabel.y { background: var(--ok); }
.tlabel.n { background: var(--bad); }
.tbr-body { flex: 1; min-width: 0; }

/* ───────── buttons ───────── */
.btn {
  display: inline-flex; align-items: center; justify-content: center; gap: 6px;
  padding: 10px 18px;
  border-radius: 12px;
  border: 1px solid var(--line);
  background: var(--panel);
  font-weight: 600;
  min-height: 44px;
}
.btn:hover { border-color: var(--accent); }
.btn.primary { background: var(--accent); color: var(--accent-ink); border-color: var(--accent); }
.btn.primary:hover { filter: brightness(1.08); }
.btn.ghost { background: transparent; }
.btn[disabled] { opacity: .45; cursor: not-allowed; }
.pager { display: flex; justify-content: space-between; gap: 10px; margin-top: 22px; flex-wrap: wrap; }

/* ───────── quiz ───────── */
.q-instr { font-family: var(--serif); font-size: 16.5px; background: var(--panel-2); border: 1px solid var(--line); border-radius: 12px; padding: 12px 16px; margin: 10px 0 14px; }
.q-instr .ko { font-family: var(--sans); font-size: 14px; color: var(--ink-2); margin-top: 6px; }
.legend { margin: 10px 0; font-size: 14px; }
.legend summary { cursor: pointer; color: var(--accent); font-weight: 600; }
.legend dl { margin: 8px 0 0; display: grid; grid-template-columns: max-content 1fr; gap: 4px 14px; }
.legend dt { font-weight: 800; font-family: var(--sans); }
.legend dd { margin: 0; color: var(--ink-2); }
.q-example { font-family: var(--serif); font-size: 16px; border-left: 4px solid var(--hl-o); padding: 6px 12px; margin: 10px 0; background: var(--panel-2); border-radius: 0 10px 10px 0; }
.q-example .tag { font-family: var(--sans); font-size: 12px; font-weight: 800; background: var(--accent); color: var(--accent-ink); padding: 1px 8px; border-radius: 99px; margin-right: 6px; }
.q-example .why { display: block; font-family: var(--sans); font-size: 13.5px; color: var(--ink-2); margin-top: 3px; }

.qbar { height: 6px; border-radius: 99px; background: var(--line); overflow: hidden; margin: 14px 0 16px; }
.qbar span { display: block; height: 100%; background: var(--accent); transition: width .25s; }
.q-meta { display: flex; justify-content: space-between; color: var(--muted); font-size: 13px; }
.qcard { background: var(--panel-2); border: 1px solid var(--line); border-radius: 14px; padding: 18px 20px; margin: 10px 0 14px; display: flex; gap: 14px; }
.qnum { flex: none; width: 32px; height: 32px; border-radius: 50%; background: var(--accent); color: var(--accent-ink); display: grid; place-items: center; font-weight: 800; font-size: 14px; }
.qtext { font-family: var(--serif); font-size: clamp(17px, 2.2vw, 20px); line-height: 1.7; min-width: 0; }
.qtext u { text-underline-offset: 3px; }
.opts { display: flex; flex-wrap: wrap; gap: 8px; }
.opt {
  min-width: 74px;
  padding: 10px 16px;
  border-radius: 12px;
  border: 1.5px solid var(--line);
  background: var(--panel);
  font-weight: 700;
  font-size: 16px;
  display: inline-flex; align-items: center; gap: 8px;
}
.opt kbd { font-family: var(--sans); font-size: 11px; color: var(--muted); border: 1px solid var(--line); border-radius: 5px; padding: 0 5px; }
.opt:hover:not([disabled]) { border-color: var(--accent); background: var(--accent-soft); }
.opt.correct { border-color: var(--ok); background: var(--ok-soft); color: var(--ok); }
.opt.wrong { border-color: var(--bad); background: var(--bad-soft); color: var(--bad); }
.opt[disabled] { cursor: default; }
.feedback { margin-top: 14px; padding: 12px 16px; border-radius: 12px; border: 1px solid transparent; }
.feedback.ok { background: var(--ok-soft); border-color: color-mix(in srgb, var(--ok) 40%, transparent); }
.feedback.bad { background: var(--bad-soft); border-color: color-mix(in srgb, var(--bad) 40%, transparent); }
.feedback .fb-h { font-weight: 800; margin-bottom: 2px; }
.feedback.ok .fb-h { color: var(--ok); }
.feedback.bad .fb-h { color: var(--bad); }
.feedback .fb-why { font-size: 15px; color: var(--ink); }
.feedback .fb-reveal { font-family: var(--serif); font-size: 17px; margin: 6px 0; }
.q-actions { display: flex; justify-content: flex-end; gap: 10px; margin-top: 14px; flex-wrap: wrap; }

.score-ring { display: flex; align-items: center; gap: 18px; margin: 8px 0 14px; flex-wrap: wrap; }
.score-big { font-size: 44px; font-weight: 800; letter-spacing: -.02em; color: var(--accent); line-height: 1; }
.score-big small { font-size: 18px; color: var(--muted); font-weight: 600; }
.review { list-style: none; margin: 10px 0 0; padding: 0; display: grid; gap: 8px; }
.review li { padding: 10px 14px; border-radius: 12px; border: 1px solid var(--line); background: var(--panel-2); font-family: var(--serif); font-size: 15.5px; }
.review li.bad { border-left: 4px solid var(--bad); }
.review li.ok { border-left: 4px solid var(--ok); }
.review .rv-meta { font-family: var(--sans); font-size: 12.5px; color: var(--ink-2); margin-top: 3px; }
.review .rv-n { font-family: var(--sans); font-weight: 800; color: var(--muted); margin-right: 6px; }
.start-box { display: flex; align-items: center; justify-content: space-between; gap: 14px; flex-wrap: wrap; margin-top: 14px; }
.best { color: var(--muted); font-size: 14px; }

/* ───────── home ───────── */
.home-hero { margin-bottom: 20px; }
.home-hero h2 { margin: 0 0 6px; font-size: clamp(24px, 3.6vw, 34px); letter-spacing: -.02em; }
.home-hero p { margin: 0; color: var(--ink-2); }
.cont-card { display: flex; align-items: center; justify-content: space-between; gap: 14px; flex-wrap: wrap; margin: 18px 0; }
.grid { display: grid; grid-template-columns: repeat(auto-fill, minmax(240px, 1fr)); gap: 12px; }
.tile { text-align: left; padding: 14px 16px; border-radius: 14px; background: var(--panel); border: 1px solid var(--line); display: block; }
.tile:hover { border-color: var(--accent); box-shadow: var(--shadow); }
.tile .t-no { font-size: 12px; font-weight: 800; color: var(--accent); letter-spacing: .06em; text-transform: uppercase; }
.tile .t-ti { font-weight: 700; margin: 2px 0 2px; line-height: 1.3; }
.tile .t-ko { color: var(--muted); font-size: 13px; min-height: 20px; }
.tile .t-bar { height: 5px; background: var(--line); border-radius: 99px; margin-top: 10px; overflow: hidden; }
.tile .t-bar span { display: block; height: 100%; background: var(--accent); }
.tile .t-meta { font-size: 12px; color: var(--muted); margin-top: 5px; }
.stat-row { display: flex; gap: 12px; flex-wrap: wrap; margin: 10px 0 0; }
.stat { flex: 1; min-width: 130px; padding: 12px 16px; background: var(--panel); border: 1px solid var(--line); border-radius: 14px; }
.stat b { display: block; font-size: 24px; letter-spacing: -.02em; }
.stat span { font-size: 13px; color: var(--muted); }
.reset-link { background: none; border: 0; color: var(--muted); text-decoration: underline; font-size: 13px; margin-top: 26px; padding: 0; }

.empty { text-align: center; color: var(--muted); padding: 40px 10px; }

/* ───────── practice-only space (문제만 풀기) ───────── */
[hidden] { display: none !important; }
.back-link { display: inline-block; color: var(--ink-2); text-decoration: none; font-size: 14px; padding: 4px 0; }
.back-link:hover { color: var(--accent); }
.pr-main { margin-top: 18px; }
.pr-actions { display: flex; gap: 10px; flex-wrap: wrap; }
.btn.big { min-height: 50px; padding: 12px 22px; font-size: 16px; flex: 1 1 260px; }
.switch { display: inline-flex; align-items: center; gap: 10px; margin-top: 16px; cursor: pointer; user-select: none; position: relative; }
.switch input { position: absolute; opacity: 0; width: 1px; height: 1px; }
.switch .track { position: relative; flex: none; width: 44px; height: 26px; border-radius: 99px; background: var(--line); transition: background .15s; }
.switch .track::after { content: ""; position: absolute; top: 3px; left: 3px; width: 20px; height: 20px; border-radius: 50%; background: #fff; box-shadow: 0 1px 3px rgba(0,0,0,.25); transition: transform .15s; }
.switch input:checked + .track { background: var(--accent); }
.switch input:checked + .track::after { transform: translateX(18px); }
.switch input:focus-visible + .track { outline: 2px solid var(--accent); outline-offset: 2px; }
.switch .sw-t { font-size: 15px; font-weight: 600; }
.pr-sets { margin-top: 14px; padding-top: 8px; padding-bottom: 8px; }
.pr-h { margin: 8px 0 2px; font-size: 14px; color: var(--ink-2); }
.set-row { display: flex; align-items: center; justify-content: space-between; gap: 14px; padding: 13px 2px; border-bottom: 1px solid var(--line); }
.set-row:last-child { border-bottom: 0; }
.set-t { min-width: 0; flex: 1; }
.set-row .btn { flex: none; white-space: nowrap; min-width: 64px; }
.set-t b { display: block; line-height: 1.35; }
.set-t small { color: var(--muted); font-size: 13px; }
.pr-top { display: flex; align-items: center; justify-content: space-between; gap: 10px; margin-bottom: 10px; }
.pr-top .btn { min-height: 34px; padding: 4px 14px; font-size: 14px; }
.q-instr-d { margin: 8px 0 12px; border: 1px solid var(--line); border-radius: 12px; background: var(--panel-2); padding: 2px 14px; }
.q-instr-d > summary { cursor: pointer; padding: 9px 0; font-size: 14px; font-weight: 600; color: var(--accent); }
.q-instr-d[open] > summary { border-bottom: 1px dashed var(--line); margin-bottom: 8px; }
.q-instr-d .q-instr { margin: 0 0 8px; background: transparent; border: 0; padding: 0; }
.q-instr-d .q-example { margin: 8px 0; }
.q-instr-d .legend { margin: 6px 0 10px; }

/* ───────── language toggle ───────── */
.lang-toggle {
  position: fixed; top: 12px; right: 16px; z-index: 41;
  display: flex; gap: 2px; padding: 3px;
  background: var(--panel); border: 1px solid var(--line);
  border-radius: 99px; box-shadow: var(--shadow);
}
.lang-toggle button {
  border: 0; background: transparent; color: var(--ink-2);
  padding: 6px 14px; min-height: 34px; border-radius: 99px;
  font-size: 13px; font-weight: 700; letter-spacing: .02em;
}
.lang-toggle button:hover { color: var(--ink); }
.lang-toggle button.on { background: var(--accent); color: var(--accent-ink); }

/* ───────── mobile ───────── */
.menu-btn { display: none; }
.scrim { display: none; }
@media (max-width: 860px) {
  .menu-btn {
    display: grid; place-items: center;
    position: fixed; top: 10px; left: 10px; z-index: 40;
    width: 44px; height: 44px; border-radius: 12px;
    border: 1px solid var(--line); background: var(--panel);
    font-size: 20px; box-shadow: var(--shadow);
  }
  .side {
    position: fixed; z-index: 50; left: 0; top: 0; bottom: 0;
    width: min(86vw, 320px);
    transform: translateX(-102%);
    transition: transform .22s;
    box-shadow: var(--shadow);
  }
  body.nav-open .side { transform: none; }
  body.nav-open .scrim { display: block; position: fixed; inset: 0; background: rgba(0,0,0,.35); z-index: 45; }
  .main { padding-top: 66px; }
  .ex { flex-direction: column; gap: 4px; }
  .ex-line { flex-wrap: wrap; }
}