/* ============================================================
   선형대수학 자기주도 학습 — Pi-Dimension 디자인 시스템 적용
   white-led · ink-anchored (#11468C) · modular scale 1.250
   mono: Nanum Gothic Coding (Google Fonts)
   ============================================================ */

:root {
  /* ink ramp */
  --ink-900: #07254E; --ink-800: #0D3672; --ink-700: #11468C;
  --ink-600: #2A5FA6; --ink-500: #4F82C2; --ink-400: #7AA3D5;
  --ink-300: #A8C2E2; --ink-200: #D2DEEE; --ink-100: #E9EFF7; --ink-50: #F4F7FB;

  /* supporting materials (quiet) */
  --moss: #506A47;    --moss-soft: #E1E7DC;
  --copper: #A75928;  --copper-soft: #F2DECF;
  --citrine: #CC9528; --citrine-soft: #F8E4BD;
  --ruby: #A8273B;    --ruby-soft: #F1D3D9;
  --opal: #8472A0;    --opal-soft: #ECE5F1;

  /* semantic */
  --bg: #FAFBFC;
  --surface: #FFFFFF;
  --surface2: #F4F6F9;
  --surface3: #ECEFF3;
  --line: #E4E8EE;
  --line2: #D4DAE3;
  --text: #1A1E26;
  --text2: #2C323C;
  --muted: #4F5663;
  --faint: #767D89;
  --accent: var(--ink-700);
  --accent-hover: var(--ink-800);
  --accent-soft: var(--ink-100);
  --accent-fg: #FFFFFF;

  --def: var(--moss);       --def-soft: var(--moss-soft);
  --thm: var(--ink-700);    --thm-soft: var(--ink-100);
  --ex: var(--copper);      --ex-soft: var(--copper-soft);
  --warn: var(--ruby);      --warn-soft: var(--ruby-soft);
  --flame: var(--citrine);  --flame-soft: var(--citrine-soft);

  --shadow-1: 0 1px 0 rgba(17,70,140,.04), 0 1px 2px rgba(17,70,140,.06);
  --shadow-2: 0 1px 0 rgba(17,70,140,.04), 0 4px 12px -2px rgba(17,70,140,.08);
  --shadow-3: 0 2px 0 rgba(17,70,140,.03), 0 12px 32px -6px rgba(17,70,140,.12);
  --focus: 0 0 0 3px rgba(17,70,140,.18);

  --r-1: 2px; --r-2: 4px; --r-3: 8px; --r-4: 12px; --r-pill: 999px;

  --font-sans: "Noto Sans KR", -apple-system, BlinkMacSystemFont,
               "Apple SD Gothic Neo", "Helvetica Neue", Arial, sans-serif;
  --font-serif: "Noto Serif KR", "Apple SD Gothic Neo", Georgia, serif;
  --font-mono: "Nanum Gothic Coding", ui-monospace, "SF Mono", Menlo, Consolas, monospace;

  --step--2: 0.694rem; --step--1: 0.833rem; --step-0: 1rem;
  --step-1: 1.25rem; --step-2: 1.563rem; --step-3: 1.953rem;
  --step-4: 2.441rem; --step-5: 3.052rem;

  --ease-out: cubic-bezier(.22,.61,.36,1);
  --dur-fast: 120ms; --dur-base: 200ms;

  --topbar-h: 3.25rem;
}

[data-theme="dark"] {
  --bg: #0E1117;
  --surface: #151A22;
  --surface2: #1A202B;
  --surface3: #232A37;
  --line: #262D3A;
  --line2: #333C4C;
  --text: #E7EBF2;
  --text2: #C9D0DC;
  --muted: #97A0B0;
  --faint: #6B7484;
  --accent: var(--ink-400);
  --accent-hover: var(--ink-300);
  --accent-soft: #1A2A44;
  --accent-fg: #0E1117;

  --def: #94B389;   --def-soft: #1B2418;
  --thm: var(--ink-400); --thm-soft: #182742;
  --ex: #CE9163;    --ex-soft: #2B1F12;
  --warn: #D97F8D;  --warn-soft: #2E181C;
  --flame: #D9AE55; --flame-soft: #2A2210;
  --opal: #A794C4;  --opal-soft: #241E30;

  --shadow-1: 0 1px 2px rgba(0,0,0,.5);
  --shadow-2: 0 4px 14px -2px rgba(0,0,0,.5);
  --shadow-3: 0 12px 32px -6px rgba(0,0,0,.6);
  --focus: 0 0 0 3px rgba(122,163,213,.28);
}

* { box-sizing: border-box; }
[hidden] { display: none !important; }
html { -webkit-text-size-adjust: 100%; scroll-padding-top: calc(var(--topbar-h) + .75rem); }
body {
  margin: 0;
  background: var(--bg);
  color: var(--text2);
  font-family: var(--font-sans);
  font-size: 16px;
  line-height: 1.7;
  word-break: keep-all;
  overflow-wrap: break-word;
  -webkit-font-smoothing: antialiased;
  text-rendering: optimizeLegibility;
}
img, svg { max-width: 100%; }
a { color: var(--accent); text-decoration: none; }
a:hover { color: var(--accent-hover); text-decoration: underline; text-underline-offset: .2em; }
button { font-family: inherit; }
:focus-visible { outline: none; box-shadow: var(--focus); border-radius: var(--r-2); }
.skip { position: absolute; left: -999px; }
.skip:focus { left: .5rem; top: .5rem; background: var(--surface); padding: .5rem 1rem; z-index: 99; }

.mono, kbd, code, .crumb, .eyebrow { font-family: var(--font-mono); }

/* ---------------- 상단바 ---------------- */
.topbar {
  position: sticky; top: 0; z-index: 40;
  display: flex; align-items: center; gap: .4rem;
  height: var(--topbar-h);
  padding: 0 .65rem;
  background: color-mix(in srgb, var(--bg) 70%, transparent);
  backdrop-filter: blur(12px);
  -webkit-backdrop-filter: blur(12px);
  border-bottom: 1px solid var(--line);
}
.brand {
  display: inline-flex; align-items: baseline; gap: .45rem;
  font-weight: 600; font-size: 1rem; color: var(--text); letter-spacing: -.01em;
}
.brand .brand-mark { font-family: var(--font-mono); color: var(--accent); font-weight: 700; font-size: 1.05rem; }
.brand:hover { text-decoration: none; color: var(--text); }
.topbar-right { margin-left: auto; display: flex; align-items: center; gap: .1rem; }
.iconbtn {
  display: inline-flex; align-items: center; justify-content: center;
  width: 2.35rem; height: 2.35rem; border: none; border-radius: var(--r-2);
  background: transparent; color: var(--muted); cursor: pointer; position: relative;
  opacity: .85; transition: opacity var(--dur-fast) var(--ease-out), background var(--dur-base);
}
.iconbtn:hover { background: var(--accent-soft); color: var(--accent); opacity: 1; text-decoration: none; }
[data-theme="dark"] .ic-moon { display: none; }
html:not([data-theme="dark"]) .ic-sun { display: none; }
.fc-due-badge {
  position: absolute; top: .1rem; right: .05rem;
  min-width: 1rem; height: 1rem; padding: 0 .22rem;
  border-radius: var(--r-pill); background: var(--warn); color: #fff;
  font-size: .64rem; font-weight: 700; line-height: 1rem; text-align: center;
  font-family: var(--font-mono);
}
.readbar { position: absolute; left: 0; right: 0; bottom: -1px; height: 2px; }
#readbarFill { height: 100%; width: 0; background: var(--accent); transition: width .1s linear; }

/* ---------------- 드로어(목차) ---------------- */
#drawer {
  position: fixed; top: 0; bottom: 0; left: 0; z-index: 60;
  width: min(86vw, 21rem);
  background: var(--surface);
  border-right: 1px solid var(--line);
  transform: translateX(-102%);
  transition: transform .25s var(--ease-out);
  overflow-y: auto; overscroll-behavior: contain;
  padding: .75rem .9rem 2rem;
}
#drawer.open { transform: none; box-shadow: var(--shadow-3); }
#scrim {
  position: fixed; inset: 0; z-index: 50; background: rgba(14,17,23,.32);
  opacity: 0; pointer-events: none; transition: opacity .25s;
}
#scrim.show { opacity: 1; pointer-events: auto; }
.drawer-head { position: sticky; top: 0; background: var(--surface); padding: .35rem 0 .6rem; z-index: 2; }
#searchBox {
  width: 100%; padding: .55rem .8rem; font-size: .95rem;
  border: 1px solid var(--line2); border-radius: var(--r-2);
  background: var(--surface2); color: var(--text); outline: none;
  font-family: var(--font-sans);
}
#searchBox:focus { border-color: var(--accent); box-shadow: var(--focus); }
#searchResults { padding: .25rem 0 .75rem; border-bottom: 1px solid var(--line); margin-bottom: .5rem; }
.sr-item { display: block; padding: .5rem .6rem; border-radius: var(--r-2); color: var(--text2); }
.sr-item:hover { background: var(--surface2); text-decoration: none; }
.sr-item .sr-loc { font-size: .75rem; color: var(--accent); font-weight: 700; font-family: var(--font-mono); }
.sr-item .sr-snip { font-size: .82rem; color: var(--muted); display: block; line-height: 1.5; }
.sr-item mark { background: var(--flame-soft); color: var(--text); border-radius: var(--r-1); padding: 0 .1em; }
.sr-none { font-size: .85rem; color: var(--muted); padding: .4rem .6rem; }

.nav-part { margin-top: 1rem; }
.nav-part > .np-title {
  font-family: var(--font-mono); font-size: .72rem; font-weight: 400;
  color: var(--faint); letter-spacing: .08em; padding: 0 .4rem .3rem;
  border-bottom: 1px solid var(--line); margin-bottom: .25rem;
}
.nav-link {
  display: flex; align-items: center; gap: .55rem;
  padding: .4rem .5rem; border-radius: var(--r-2); color: var(--text2); font-size: .93rem;
}
.nav-link:hover { background: var(--surface2); text-decoration: none; }
.nav-link.current { background: var(--accent-soft); color: var(--accent); font-weight: 700; }
.nav-num {
  flex: none; width: 1.5rem; height: 1.5rem; border-radius: var(--r-2);
  display: inline-flex; align-items: center; justify-content: center;
  font-size: .72rem; font-family: var(--font-mono);
  background: var(--surface2); color: var(--muted);
}
.nav-link.done .nav-num { background: var(--def-soft); color: var(--def); }
.nav-link.current .nav-num { background: var(--accent); color: var(--accent-fg); }

/* ---------------- 본문 공통 ---------------- */
.doc, .app {
  max-width: 46rem; margin: 0 auto;
  padding: 1.25rem 1.15rem 4.5rem;
}
.page-head { margin: .75rem 0 1.75rem; }
.crumb {
  font-family: var(--font-mono); font-size: .75rem; color: var(--accent);
  letter-spacing: .06em;
}
.crumb .stepno { color: var(--faint); }
.page-head h1 {
  margin: .25rem 0 .35rem; font-size: var(--step-3); line-height: 1.25;
  letter-spacing: -.02em; color: var(--text); font-weight: 600;
}
.page-sub { margin: 0; color: var(--muted); font-size: .95rem; }
.page-tools { display: flex; flex-wrap: wrap; gap: .4rem; margin-top: 1rem; }
.chip {
  display: inline-flex; align-items: center; gap: .3rem;
  font-size: .78rem; font-weight: 500; padding: .28rem .7rem;
  border-radius: var(--r-pill); border: 1px solid var(--line2);
  background: var(--surface); color: var(--text2); cursor: pointer;
  transition: border-color var(--dur-base), color var(--dur-base);
}
.chip:hover { border-color: var(--accent); color: var(--accent); text-decoration: none; }
.chip.ghost { cursor: default; color: var(--muted); font-family: var(--font-mono); font-size: .72rem; }
.chip.ghost:hover { border-color: var(--line2); color: var(--muted); }

.doc h2 {
  font-size: var(--step-1); margin: 2.4rem 0 .8rem; padding-top: .5rem;
  letter-spacing: -.01em; color: var(--text); font-weight: 600;
  display: flex; align-items: center; gap: .5rem;
  border-top: 1px solid var(--line);
}
.doc h3 { font-size: 1.08rem; margin: 1.7rem 0 .5rem; color: var(--text); font-weight: 600; }
.doc p { margin: .8rem 0; }
.doc li { margin: .3rem 0; }
.doc hr { border: none; border-top: 1px solid var(--line); margin: 2rem 0; }
.doc code { background: var(--surface2); border-radius: var(--r-1); padding: .1em .35em; font-size: .88em; }

/* 절 읽음 체크 */
.sec-check {
  flex: none; margin-left: auto;
  width: 1.6rem; height: 1.6rem; border-radius: var(--r-2);
  border: 1px solid var(--line2); background: var(--surface);
  color: transparent; cursor: pointer;
  display: inline-flex; align-items: center; justify-content: center; font-size: .8rem;
  transition: all var(--dur-base) var(--ease-out);
}
.sec-check:hover { border-color: var(--def); color: var(--line2); }
.sec-check.on { background: var(--def); border-color: var(--def); color: #fff; }

/* ---------------- 카드(정의/정리/예제) ---------------- */
p.card, blockquote.card-bq {
  border-radius: var(--r-3);
  padding: 1rem 1.15rem;
  margin: 1rem 0;
  border: 1px solid var(--line);
}
blockquote.card-bq { margin: 1rem 0; }
blockquote.card-bq p { margin: 0; }
blockquote.card-bq p + p { margin-top: .5rem; }
p.card.def, blockquote.card-bq.def {
  background: color-mix(in srgb, var(--def-soft) 45%, var(--surface));
  border-color: color-mix(in srgb, var(--def) 25%, var(--line));
}
p.card.def > strong:first-child, blockquote.card-bq.def strong:first-child { color: var(--def); }
p.card.thm, blockquote.card-bq.thm {
  background: color-mix(in srgb, var(--thm-soft) 55%, var(--surface));
  border-color: color-mix(in srgb, var(--thm) 22%, var(--line));
}
p.card.thm > strong:first-child, blockquote.card-bq.thm strong:first-child { color: var(--thm); }
p.card.ex {
  background: color-mix(in srgb, var(--ex-soft) 30%, var(--surface));
  border-color: var(--line);
}
p.card.ex > strong:first-child { color: var(--ex); }

/* ---------------- 증명 / 정답 접기 ---------------- */
details.proof, details.answers {
  margin: .6rem 0 1.1rem;
  border: 1px dashed var(--line2);
  border-radius: var(--r-3);
  background: var(--surface);
  overflow: hidden;
}
details.proof > summary, details.answers > summary {
  cursor: pointer; list-style: none;
  padding: .5rem 1rem; font-size: .78rem; font-weight: 400;
  font-family: var(--font-mono); letter-spacing: .06em; color: var(--thm);
  user-select: none;
}
details.proof > summary::before, details.answers > summary::before { content: "▸ "; }
details.proof[open] > summary::before, details.answers[open] > summary::before { content: "▾ "; }
details.proof > summary::-webkit-details-marker, details.answers > summary::-webkit-details-marker { display: none; }
details.proof[open], details.answers[open] { background: var(--surface2); }
details.proof > *:not(summary), details.answers > *:not(summary) { margin-left: 1rem; margin-right: 1rem; }
details.proof > p:last-child, details.answers > :last-child { margin-bottom: .9rem; }
details.answers > summary { color: var(--def); }

/* ---------------- 표 / 수식 ---------------- */
.table-wrap { overflow-x: auto; margin: 1rem 0; border-radius: var(--r-3); border: 1px solid var(--line); }
.table-wrap table { border-collapse: collapse; width: 100%; min-width: 28rem; font-size: .92rem; }
.table-wrap th, .table-wrap td { padding: .55rem .8rem; border-bottom: 1px solid var(--line); text-align: left; vertical-align: top; }
.table-wrap thead th { background: var(--surface2); font-weight: 600; position: sticky; top: 0; color: var(--text); }
.table-wrap tr:last-child td { border-bottom: none; }
.katex { font-size: 1.05em; }
.katex-display { overflow-x: auto; overflow-y: hidden; padding: .3rem 0; }

/* ---------------- 각주 ---------------- */
.doc-foot { margin-top: 2.5rem; }
.footnote { font-size: .8rem; color: var(--muted); border-top: 1px solid var(--line); padding-top: .75rem; }
.footnote hr { display: none; }
.footnote li { margin: .35rem 0; }

/* ---------------- 연습문제 체크 ---------------- */
.exli { position: relative; }
.ex-check {
  position: absolute; left: -2.2rem; top: .35rem;
  width: 1.25rem; height: 1.25rem; border-radius: var(--r-1);
  border: 1px solid var(--line2); background: var(--surface);
  cursor: pointer; color: transparent;
  display: inline-flex; align-items: center; justify-content: center; font-size: .7rem;
}
.ex-check.on { background: var(--def); border-color: var(--def); color: #fff; }
.exli.done { color: var(--muted); }
section[data-sec*="연습문제"] ol { padding-left: 2.4rem; }

/* ---------------- 장 확인 박스 ---------------- */
.check-aside {
  margin-top: 2.5rem; padding: 1.1rem 1.25rem;
  border: 1px solid var(--line); border-radius: var(--r-3); background: var(--surface);
}
.check-aside .eyebrow {
  font-size: .72rem; letter-spacing: .08em; color: var(--faint); display: block; margin-bottom: .35rem;
}
.check-aside p { margin: 0 0 .7rem; font-size: .92rem; color: var(--muted); }
.check-aside .row { display: flex; flex-wrap: wrap; gap: .5rem; }

/* ---------------- 이전/다음 ---------------- */
.pagenav { display: grid; grid-template-columns: 1fr 1fr; gap: .75rem; margin-top: 1.5rem; }
.pagenav a {
  display: block; padding: .8rem 1rem; border-radius: var(--r-3);
  border: 1px solid var(--line); background: var(--surface); color: var(--text2);
  transition: box-shadow var(--dur-base), transform var(--dur-base);
}
.pagenav a:hover { box-shadow: var(--shadow-2); transform: translateY(-1px); text-decoration: none; }
.pagenav .pn-label { display: block; font-size: .7rem; color: var(--faint); font-family: var(--font-mono); letter-spacing: .06em; }
.pagenav .pn-title { font-weight: 600; color: var(--accent); }
.pagenav a.pn-next { text-align: right; grid-column: 2; }
.pagenav a.pn-prev { grid-column: 1; }

/* ---------------- 버튼 ---------------- */
.btn {
  display: inline-flex; align-items: center; justify-content: center; gap: .4rem;
  padding: .6rem 1.15rem; border-radius: var(--r-2); font-weight: 600; font-size: .95rem;
  border: 1px solid var(--line2); background: var(--surface); color: var(--text2);
  cursor: pointer; transition: all var(--dur-base) var(--ease-out);
}
.btn:hover { background: var(--accent-soft); border-color: var(--accent); color: var(--accent); text-decoration: none; }
.btn:active { transform: translateY(1px); }
.btn.primary { background: var(--accent); border-color: var(--accent); color: var(--accent-fg); }
.btn.primary:hover { background: var(--accent-hover); border-color: var(--accent-hover); color: var(--accent-fg); }

/* ---------------- 홈(index) ---------------- */
.hero { margin: 1.75rem 0 2.25rem; }
.hero-kicker {
  font-family: var(--font-mono); color: var(--faint); font-size: .78rem;
  letter-spacing: .06em; margin: 0 0 .5rem;
}
.hero h1 {
  font-family: var(--font-serif); font-weight: 500;
  font-size: var(--step-4); line-height: 1.18; margin: 0 0 .7rem;
  letter-spacing: -.02em; color: var(--text);
}
.hero h1 span { color: var(--accent); }
.hero-desc { color: var(--muted); max-width: 36rem; }
.hero-actions { display: flex; flex-wrap: wrap; gap: .6rem; margin: 1.2rem 0 1.4rem; }

/* 오늘의 학습 카드 (index) */
.today-card {
  border: 1px solid var(--line); border-radius: var(--r-3);
  background: var(--surface); padding: 1.1rem 1.25rem; max-width: 34rem;
  margin-bottom: 1.25rem;
}
.today-card .eyebrow {
  font-size: .72rem; letter-spacing: .08em; color: var(--faint);
  display: flex; justify-content: space-between; align-items: baseline; margin-bottom: .4rem;
}
.today-card .tc-title { font-weight: 600; color: var(--text); font-size: 1.05rem; }
.today-card .tc-sub { font-size: .85rem; color: var(--muted); margin: .15rem 0 .75rem; }
.today-card .tc-row { display: flex; align-items: center; gap: .75rem; flex-wrap: wrap; }
.streak {
  font-family: var(--font-mono); font-size: .8rem; color: var(--flame);
  background: var(--flame-soft); border-radius: var(--r-pill); padding: .2rem .65rem;
}

.hero-progress {
  background: var(--surface); border: 1px solid var(--line); border-radius: var(--r-3);
  padding: .9rem 1.1rem; max-width: 34rem;
}
.hp-row { display: flex; justify-content: space-between; font-size: .85rem; margin-bottom: .4rem; }
.hp-row strong { font-family: var(--font-mono); }
.hp-bar { height: .4rem; border-radius: var(--r-pill); background: var(--surface3); overflow: hidden; }
#totalFill { height: 100%; width: 0; border-radius: var(--r-pill); background: var(--accent); transition: width .4s var(--ease-out); }
.hp-meta { font-size: .78rem; color: var(--faint); margin-top: .45rem; font-family: var(--font-mono); }
.guide-links { margin-top: 1.1rem; font-size: .85rem; color: var(--muted); display: flex; flex-wrap: wrap; gap: .4rem; align-items: center; }

.part { margin: 2rem 0; }
.part h2 {
  font-size: .95rem; margin: 0 0 .6rem; color: var(--text);
  display: flex; flex-wrap: wrap; align-items: baseline; gap: .5rem;
  border-bottom: 1px solid var(--line); padding-bottom: .4rem;
}
.part h2 small { font-weight: 400; color: var(--faint); font-size: .8rem; }
.lesson {
  display: flex; align-items: center; gap: .8rem;
  background: var(--surface); border: 1px solid var(--line); border-radius: var(--r-3);
  padding: .7rem .9rem; margin: .5rem 0; color: var(--text2);
  transition: box-shadow var(--dur-base), transform var(--dur-base);
}
.lesson:hover { box-shadow: var(--shadow-2); transform: translateY(-1px); text-decoration: none; }
.lesson-no {
  flex: none; width: 2rem; height: 2rem; border-radius: var(--r-2);
  display: inline-flex; align-items: center; justify-content: center;
  font-family: var(--font-mono); font-size: .85rem;
  background: var(--accent-soft); color: var(--accent);
}
.lesson.done .lesson-no { background: var(--def); color: #fff; }
.lesson-body { flex: 1; min-width: 0; }
.lesson-t { display: block; font-weight: 600; color: var(--text); }
.lesson-sub { display: block; font-size: .8rem; color: var(--faint); white-space: nowrap; overflow: hidden; text-overflow: ellipsis; }
.lesson-bar { display: block; height: .25rem; border-radius: var(--r-pill); background: var(--surface3); margin-top: .45rem; overflow: hidden; }
.lesson-fill { display: block; height: 100%; width: 0; background: var(--def); border-radius: var(--r-pill); transition: width .4s; }
.lesson-pct { flex: none; font-size: .75rem; font-family: var(--font-mono); color: var(--faint); min-width: 2.6rem; text-align: right; }

.howto { border-top: 1px solid var(--line); padding-top: 1.25rem; margin-top: 2.5rem; }
.howto h2 { font-size: 1rem; margin: 0 0 .5rem; color: var(--text); }
.howto ol { margin: 0; padding-left: 1.2rem; }
.howto li { margin: .45rem 0; }

/* ---------------- 플래시카드 ---------------- */
.app-head h1 { font-size: var(--step-2); margin: .4rem 0 .3rem; color: var(--text); font-weight: 600; }
.fc-toolbar { display: flex; flex-wrap: wrap; gap: .5rem; align-items: center; margin: 1rem 0; }
.fc-toolbar select, .today-tools select, .today-tools input[type="time"] {
  padding: .5rem .7rem; border-radius: var(--r-2); border: 1px solid var(--line2);
  background: var(--surface); color: var(--text); font-size: .9rem; max-width: 100%;
  font-family: var(--font-sans);
}
.fc-stats { font-size: .78rem; color: var(--faint); font-family: var(--font-mono); }
.fc-stage { margin: 1rem 0; }
.fc-card {
  min-height: 16rem;
  background: var(--surface); border: 1px solid var(--line); border-radius: var(--r-4);
  box-shadow: var(--shadow-2); padding: 1.4rem 1.3rem 2.6rem; position: relative;
  outline: none;
}
.fc-front { font-size: 1.12rem; font-weight: 600; line-height: 1.6; color: var(--text); }
.fc-kind {
  display: inline-block; font-family: var(--font-mono); font-size: .68rem;
  letter-spacing: .08em; border-radius: var(--r-1); padding: .12rem .5rem;
  margin-right: .45rem; vertical-align: .15em;
}
.fc-kind.def { background: var(--def-soft); color: var(--def); }
.fc-kind.thm { background: var(--thm-soft); color: var(--thm); }
.fc-back { border-top: 1px dashed var(--line2); margin-top: 1rem; padding-top: 1rem; font-size: .97rem; font-weight: 400; color: var(--text2); }
.fc-back .table-wrap table { min-width: 20rem; }
.fc-src { position: absolute; left: 1.3rem; right: 1.3rem; bottom: .8rem; font-size: .74rem; color: var(--faint); font-family: var(--font-mono); }
.fc-empty {
  text-align: center; color: var(--muted); padding: 3rem 1rem;
  background: var(--surface); border: 1px dashed var(--line2); border-radius: var(--r-4);
}
.fc-controls { display: flex; gap: .6rem; justify-content: center; margin: 1rem 0; flex-wrap: wrap; }
.btn.big { padding: .8rem 2.2rem; font-size: 1rem; }
.btn.grade { flex-direction: column; gap: 0; line-height: 1.3; min-width: 6.2rem; }
.btn.grade small { font-weight: 400; color: var(--faint); font-size: .7rem; font-family: var(--font-mono); }
.btn.grade kbd { display: none; }
.btn.g0:hover { border-color: var(--warn); color: var(--warn); background: var(--warn-soft); }
.btn.g1:hover { border-color: var(--flame); color: var(--flame); background: var(--flame-soft); }
.btn.g2:hover { border-color: var(--def); color: var(--def); background: var(--def-soft); }
kbd {
  font-size: .72rem; background: var(--surface2);
  border: 1px solid var(--line2); border-bottom-width: 2px; border-radius: var(--r-1); padding: 0 .35rem;
}

/* ---------------- 셀프 퀴즈 ---------------- */
.qz-decks { display: grid; grid-template-columns: repeat(auto-fill, minmax(15rem, 1fr)); gap: .6rem; margin: 1.25rem 0; }
.qz-deck {
  text-align: left; padding: .8rem 1rem; border-radius: var(--r-3);
  border: 1px solid var(--line); background: var(--surface); cursor: pointer;
  color: var(--text2); transition: box-shadow var(--dur-base), transform var(--dur-base);
  display: flex; align-items: center; gap: .75rem;
}
.qz-deck:hover { box-shadow: var(--shadow-2); transform: translateY(-1px); }
.qz-deck .qd-no {
  flex: none; width: 1.9rem; height: 1.9rem; border-radius: var(--r-2);
  display: inline-flex; align-items: center; justify-content: center;
  font-family: var(--font-mono); font-size: .8rem;
  background: var(--accent-soft); color: var(--accent);
}
.qz-deck .qd-t { font-weight: 600; color: var(--text); display: block; font-size: .92rem; }
.qz-deck .qd-best { font-size: .72rem; font-family: var(--font-mono); color: var(--faint); }
.qz-deck .qd-best.pass { color: var(--def); }

.qz-run { max-width: 40rem; }
.qz-meta { display: flex; justify-content: space-between; align-items: center; font-family: var(--font-mono); font-size: .78rem; color: var(--faint); margin-bottom: .6rem; }
.qz-bar { height: .25rem; background: var(--surface3); border-radius: var(--r-pill); overflow: hidden; margin-bottom: 1.25rem; }
.qz-bar > div { height: 100%; background: var(--accent); border-radius: var(--r-pill); transition: width .3s var(--ease-out); }
.qz-q { font-size: 1.08rem; font-weight: 600; color: var(--text); margin: 0 0 1rem; line-height: 1.6; }
.qz-opts { display: grid; gap: .55rem; }
.qz-opt {
  text-align: left; padding: .75rem 1rem; border-radius: var(--r-3);
  border: 1px solid var(--line2); background: var(--surface); color: var(--text2);
  cursor: pointer; font-size: .97rem; line-height: 1.55;
  transition: border-color var(--dur-fast), background var(--dur-fast);
}
.qz-opt:hover { border-color: var(--accent); background: var(--accent-soft); }
.qz-opt.correct { border-color: var(--def); background: var(--def-soft); color: var(--text); }
.qz-opt.wrong { border-color: var(--warn); background: var(--warn-soft); color: var(--text); }
.qz-opt:disabled { cursor: default; opacity: .85; }
.qz-exp {
  margin-top: 1rem; padding: .9rem 1.1rem; border-radius: var(--r-3);
  background: var(--surface2); border: 1px solid var(--line); font-size: .92rem;
}
.qz-exp .eyebrow { font-size: .7rem; letter-spacing: .08em; color: var(--faint); display: block; margin-bottom: .3rem; }
.qz-next { margin-top: 1rem; display: flex; justify-content: flex-end; }
.qz-result { text-align: center; padding: 2.5rem 1rem; }
.qz-result .qr-score { font-family: var(--font-mono); font-size: var(--step-4); color: var(--accent); display: block; }
.qz-result .qr-label { color: var(--muted); margin: .5rem 0 1.5rem; }
.qz-result .row { display: flex; gap: .6rem; justify-content: center; flex-wrap: wrap; }

/* ---------------- 개념 그래프 ---------------- */
.graph-wrap {
  overflow: auto; border: 1px solid var(--line); border-radius: var(--r-3);
  background: var(--surface); margin: 1rem 0;
  background-image: radial-gradient(color-mix(in srgb, var(--line) 60%, transparent) 1px, transparent 1px);
  background-size: 22px 22px;
}
.graph-wrap svg { display: block; min-width: 700px; }
.g-edge { stroke: var(--line2); stroke-width: 1.2; fill: none; transition: stroke var(--dur-base); }
.g-edge.hi-in { stroke: var(--copper); stroke-width: 2; }
.g-edge.hi-out { stroke: var(--accent); stroke-width: 2; }
.g-edge.dim { stroke: color-mix(in srgb, var(--line) 50%, transparent); }
.g-node { cursor: pointer; }
.g-node rect {
  fill: var(--surface); stroke: var(--line2); stroke-width: 1; rx: 6;
  transition: stroke var(--dur-base), fill var(--dur-base);
}
.g-node text { fill: var(--text2); font-size: 12px; font-family: var(--font-sans); }
.g-node .g-num { fill: var(--faint); font-family: var(--font-mono); font-size: 10px; }
.g-node.done rect { fill: color-mix(in srgb, var(--def-soft) 55%, var(--surface)); stroke: var(--def); }
.g-node.part-read rect { stroke: var(--accent); }
.g-node.sel rect { stroke: var(--accent); stroke-width: 2; fill: var(--accent-soft); }
.g-node.dim { opacity: .35; }
.g-info {
  border: 1px solid var(--line); border-radius: var(--r-3); background: var(--surface);
  padding: 1rem 1.15rem; margin: 1rem 0;
}
.g-info .eyebrow { font-size: .7rem; letter-spacing: .08em; color: var(--faint); }
.g-info h2 { margin: .2rem 0 .4rem; font-size: 1.15rem; color: var(--text); }
.g-info .gi-row { font-size: .88rem; margin: .3rem 0; }
.g-info .gi-row b { color: var(--muted); font-weight: 500; font-size: .78rem; font-family: var(--font-mono); letter-spacing: .04em; }
.g-legend { display: flex; flex-wrap: wrap; gap: .9rem; font-size: .75rem; color: var(--faint); font-family: var(--font-mono); margin-top: .5rem; }
.g-legend i { display: inline-block; width: .8rem; height: .8rem; border-radius: var(--r-1); vertical-align: -2px; margin-right: .3rem; }

/* ---------------- 오늘의 학습 ---------------- */
.today-head { display: flex; align-items: baseline; justify-content: space-between; flex-wrap: wrap; gap: .5rem; }
.day-count { font-family: var(--font-mono); color: var(--accent); font-size: .85rem; }
.mission {
  border: 1px solid var(--line); border-radius: var(--r-3); background: var(--surface);
  padding: 1.1rem 1.25rem; margin: 1rem 0;
}
.mission .m-eyebrow {
  font-family: var(--font-mono); font-size: .72rem; letter-spacing: .08em;
  color: var(--faint); display: flex; justify-content: space-between; margin-bottom: .3rem;
}
.mission h2 { margin: 0 0 .25rem; font-size: 1.2rem; color: var(--text); }
.mission .m-sub { color: var(--muted); font-size: .9rem; margin: 0 0 .9rem; }
.task {
  display: flex; align-items: flex-start; gap: .7rem;
  padding: .65rem .25rem; border-top: 1px solid var(--line);
}
.task-check {
  flex: none; width: 1.4rem; height: 1.4rem; margin-top: .1rem;
  border-radius: var(--r-pill); border: 1px solid var(--line2);
  display: inline-flex; align-items: center; justify-content: center;
  font-size: .7rem; color: transparent; background: var(--surface);
}
.task.done .task-check { background: var(--def); border-color: var(--def); color: #fff; }
.task.done .task-label { color: var(--faint); text-decoration: line-through; text-decoration-color: var(--line2); }
.task-label { font-size: .95rem; }
.task-label a { font-weight: 600; }
.task-meta { display: block; font-size: .76rem; color: var(--faint); font-family: var(--font-mono); }
.m-done-banner {
  margin-top: .9rem; padding: .7rem 1rem; border-radius: var(--r-2);
  background: var(--def-soft); color: var(--def); font-size: .9rem; font-weight: 600;
}
.today-week { display: flex; gap: .35rem; margin: 1rem 0; flex-wrap: wrap; }
.wk-day {
  flex: none; width: 2.1rem; text-align: center; font-family: var(--font-mono);
  font-size: .68rem; color: var(--faint); padding: .3rem 0 .35rem;
  border: 1px solid var(--line); border-radius: var(--r-2); background: var(--surface);
}
.wk-day b { display: block; font-size: .85rem; font-weight: 400; color: var(--text2); }
.wk-day.hit { background: var(--flame-soft); border-color: var(--flame); }
.wk-day.hit b { color: var(--flame); }
.wk-day.today-mark { border-color: var(--accent); }
.today-tools {
  border-top: 1px solid var(--line); margin-top: 2rem; padding-top: 1.25rem;
  display: grid; gap: .75rem;
}
.today-tools .tt-row { display: flex; align-items: center; gap: .6rem; flex-wrap: wrap; font-size: .9rem; }
.today-tools .tt-row label { color: var(--muted); }
.notice { font-size: .8rem; color: var(--faint); }
.plan-list { margin-top: 2rem; border-top: 1px solid var(--line); padding-top: 1rem; }
.plan-list h2 { font-size: 1rem; color: var(--text); }
.plan-row {
  display: flex; gap: .7rem; align-items: baseline; padding: .35rem .25rem;
  font-size: .88rem; border-bottom: 1px solid color-mix(in srgb, var(--line) 55%, transparent);
}
.plan-row .pl-day { flex: none; width: 3.4rem; font-family: var(--font-mono); font-size: .72rem; color: var(--faint); }
.plan-row.done .pl-day { color: var(--def); }
.plan-row.cur { background: var(--accent-soft); border-radius: var(--r-2); }
.plan-row.cur .pl-day { color: var(--accent); font-weight: 700; }
.plan-row .pl-t { color: var(--text2); }
.plan-row .pl-ch { color: var(--faint); font-size: .78rem; }

/* ---------------- 설치 배너 ---------------- */
#installBtn { display: none; }
#installBtn.show { display: inline-flex; }

/* ---------------- 데스크톱 ---------------- */
@media (min-width: 900px) {
  body { font-size: 17px; }
  .doc, .app { padding-top: 2.25rem; }
  .page-head h1 { font-size: var(--step-4); }
  .hero h1 { font-size: var(--step-5); }
  .btn.grade kbd { display: inline-block; margin-top: .2rem; }
}
@media (min-width: 1200px) {
  #drawer { transform: none; top: var(--topbar-h); box-shadow: none; }
  #drawer.closed-desktop { transform: translateX(-102%); }
  #scrim { display: none; }
  .doc, .app { margin-left: calc(21rem + (100% - 21rem - 46rem) / 2); }
  body.drawer-hidden .doc, body.drawer-hidden .app { margin-left: auto; }
}

@media print {
  .topbar, #drawer, #scrim, .pagenav, .page-tools, .sec-check, .ex-check, .check-aside { display: none !important; }
}