:root {
  --bg: #f6f7fb; --card: #ffffff; --ink: #1d2033; --ink2: #5a6072; --ink3: #8a90a2;
  --line: #e4e7ef; --soft: #eef0f7; --pri: #4f5bd5; --pri2: #3b45b8; --pri-soft: #e8eafc;
  --ok: #138a52; --ok-soft: #e3f6ec; --bad: #d03b3b; --bad-soft: #fdeaea; --warn: #b7791f; --warn-soft: #fdf3e1;
  --code-bg: #f7f8fc; --shadow: 0 1px 2px rgba(20,24,60,.05), 0 4px 14px rgba(20,24,60,.05);
  --r: 14px; --mono: "D2Coding", "JetBrains Mono", "Cascadia Mono", "SFMono-Regular", Menlo, Consolas, "Noto Sans Mono CJK KR", monospace;
  color-scheme: light;
}
@media (prefers-color-scheme: dark) {
  :root:not([data-theme="light"]) {
    --bg: #12141c; --card: #1b1e29; --ink: #e8eaf2; --ink2: #aeb3c3; --ink3: #7e8497;
    --line: #2b2f3e; --soft: #232736; --pri: #8b93ff; --pri2: #a7adff; --pri-soft: #272b4a;
    --ok: #4cc58a; --ok-soft: #173326; --bad: #ff7676; --bad-soft: #3a1c1f; --warn: #f0b252; --warn-soft: #3a2d16;
    --code-bg: #161925; --shadow: none; color-scheme: dark;
  }
}
:root[data-theme="dark"] {
  --bg: #12141c; --card: #1b1e29; --ink: #e8eaf2; --ink2: #aeb3c3; --ink3: #7e8497;
  --line: #2b2f3e; --soft: #232736; --pri: #8b93ff; --pri2: #a7adff; --pri-soft: #272b4a;
  --ok: #4cc58a; --ok-soft: #173326; --bad: #ff7676; --bad-soft: #3a1c1f; --warn: #f0b252; --warn-soft: #3a2d16;
  --code-bg: #161925; --shadow: none; color-scheme: dark;
}
* { box-sizing: border-box; }
html { -webkit-text-size-adjust: 100%; }
body {
  margin: 0; background: var(--bg); color: var(--ink);
  font: 15px/1.6 -apple-system, BlinkMacSystemFont, "Apple SD Gothic Neo", "Pretendard", "Noto Sans KR", "Malgun Gothic", "Segoe UI", sans-serif;
  word-break: keep-all; overflow-wrap: anywhere;
}
a { color: var(--pri); text-decoration: none; }
button, input, select, textarea { font: inherit; color: inherit; }
img { max-width: 100%; }
[hidden] { display: none !important; }

/* 레이아웃 */
#top {
  position: sticky; top: 0; z-index: 20; background: color-mix(in srgb, var(--bg) 88%, transparent);
  backdrop-filter: blur(10px); -webkit-backdrop-filter: blur(10px);
  padding: calc(env(safe-area-inset-top, 0px) + 10px) 16px 10px; display: flex; align-items: center; gap: 10px;
  border-bottom: 1px solid var(--line);
}
#top .back { border: 0; background: none; font-size: 22px; line-height: 1; padding: 4px 6px 4px 0; cursor: pointer; color: var(--ink2); }
#top h1 { font-size: 17px; margin: 0; flex: 1; white-space: nowrap; overflow: hidden; text-overflow: ellipsis; }
.dday { font-size: 12px; font-weight: 700; color: var(--pri); background: var(--pri-soft); padding: 3px 9px; border-radius: 99px; white-space: nowrap; }
main { max-width: 760px; margin: 0 auto; padding: 14px 16px calc(84px + env(safe-area-inset-bottom, 0px)); }
#nav {
  position: fixed; left: 0; right: 0; bottom: 0; z-index: 20; display: flex; justify-content: center;
  background: var(--card); border-top: 1px solid var(--line); padding: 4px 6px calc(env(safe-area-inset-bottom, 0px) + 4px);
}
#nav a { flex: 1; max-width: 140px; text-align: center; color: var(--ink3); font-size: 11px; padding: 6px 0 4px; border-radius: 10px; }
#nav a b { display: block; font-size: 19px; line-height: 1.2; font-weight: 400; }
#nav a.on { color: var(--pri); font-weight: 700; }

/* 카드, 버튼 */
.card { background: var(--card); border: 1px solid var(--line); border-radius: var(--r); padding: 14px 16px; margin: 0 0 12px; box-shadow: var(--shadow); }
.card h2 { font-size: 16px; margin: 0 0 8px; }
.card h3 { font-size: 14px; margin: 12px 0 6px; color: var(--ink2); }
.muted { color: var(--ink3); font-size: 13px; }
.small { font-size: 13px; }
.row { display: flex; align-items: center; gap: 8px; flex-wrap: wrap; }
.row.sp { justify-content: space-between; }
.grow { flex: 1; min-width: 0; }
.btn {
  display: inline-flex; align-items: center; justify-content: center; gap: 6px; border: 1px solid var(--line);
  background: var(--card); color: var(--ink); border-radius: 11px; padding: 10px 14px; cursor: pointer;
  font-weight: 600; font-size: 14px; min-height: 42px; text-align: center;
}
.btn:active { transform: translateY(1px); }
.btn.pri { background: var(--pri); border-color: var(--pri); color: #fff; }
.btn.pri:disabled { opacity: .5; }
.btn.ok { background: var(--ok); border-color: var(--ok); color: #fff; }
.btn.bad { background: var(--bad-soft); border-color: transparent; color: var(--bad); }
.btn.ghost { background: transparent; }
.btn.sm { min-height: 32px; padding: 5px 10px; font-size: 13px; border-radius: 9px; }
.btn.block { width: 100%; }
.chip { display: inline-block; font-size: 12px; padding: 2px 8px; border-radius: 99px; background: var(--soft); color: var(--ink2); white-space: nowrap; }
.chip.pri { background: var(--pri-soft); color: var(--pri); }
.chip.ok { background: var(--ok-soft); color: var(--ok); }
.chip.bad { background: var(--bad-soft); color: var(--bad); }
.chip.warn { background: var(--warn-soft); color: var(--warn); }

/* 홈 */
.hero { display: grid; grid-template-columns: repeat(3, 1fr); gap: 8px; text-align: center; }
.hero div { background: var(--soft); border-radius: 12px; padding: 10px 4px; }
.hero b { display: block; font-size: 22px; line-height: 1.2; }
.hero span { font-size: 12px; color: var(--ink3); }
.goal { height: 8px; background: var(--soft); border-radius: 99px; overflow: hidden; margin-top: 10px; }
.goal i { display: block; height: 100%; background: var(--pri); border-radius: 99px; }
.actions { display: grid; grid-template-columns: 1fr 1fr; gap: 8px; }
.act {
  display: flex; flex-direction: column; align-items: flex-start; gap: 2px; padding: 13px 14px; border-radius: var(--r);
  background: var(--card); border: 1px solid var(--line); color: var(--ink); cursor: pointer; text-align: left; box-shadow: var(--shadow);
}
.act b { font-size: 15px; }
.act span { font-size: 12px; color: var(--ink3); }
.act.main { background: var(--pri); border-color: var(--pri); color: #fff; }
.act.main span { color: rgba(255,255,255,.8); }
.group-title { font-size: 13px; font-weight: 700; color: var(--ink3); margin: 18px 4px 8px; letter-spacing: .02em; }
.part { display: flex; align-items: center; gap: 12px; padding: 12px 14px; background: var(--card); border: 1px solid var(--line);
  border-radius: var(--r); margin-bottom: 8px; color: var(--ink); box-shadow: var(--shadow); }
.part .ic { width: 40px; height: 40px; border-radius: 11px; display: grid; place-items: center; font-weight: 800; font-size: 12px;
  background: var(--pri-soft); color: var(--pri); flex: none; }
.part .meta { flex: 1; min-width: 0; }
.part .name { font-weight: 700; }
.bar { height: 6px; background: var(--soft); border-radius: 99px; overflow: hidden; margin-top: 6px; display: flex; }
.bar i { display: block; height: 100%; }
.bar .m { background: var(--ok); } .bar .l { background: color-mix(in srgb, var(--pri) 55%, transparent); }
.banner { border-radius: 12px; padding: 10px 14px; margin-bottom: 12px; font-size: 14px; background: var(--warn-soft); color: var(--warn); }
.banner.info { background: var(--pri-soft); color: var(--pri); }
.links { display: grid; grid-template-columns: 1fr 1fr; gap: 8px; }

/* 문제 */
.qhead { display: flex; align-items: center; gap: 6px; flex-wrap: wrap; margin-bottom: 8px; }
.progress { height: 4px; background: var(--soft); border-radius: 99px; overflow: hidden; margin: 0 0 12px; }
.progress i { display: block; height: 100%; background: var(--pri); transition: width .2s; }
.qtext { font-size: 16px; font-weight: 600; margin: 4px 0 10px; white-space: pre-line; }
.qtext p { margin: 0 0 6px; }
.def { font-size: 16px; background: var(--soft); border-radius: 12px; padding: 12px 14px; margin: 8px 0 12px; }
.code { display: flex; background: var(--code-bg); border: 1px solid var(--line); border-radius: 12px; overflow: hidden; margin: 8px 0 12px; }
.code .gut { flex: none; overflow: visible; margin: 0; padding: 10px 8px 10px 10px; text-align: right; color: var(--ink3); user-select: none; border-right: 1px solid var(--line);
  font: 13px/1.55 var(--mono); background: color-mix(in srgb, var(--code-bg) 60%, var(--soft)); }
.code pre { margin: 0; padding: 10px 12px; overflow-x: auto; flex: 1; min-width: 0; font: 13px/1.55 var(--mono); tab-size: 4; }
.code pre code { font: inherit; background: none !important; padding: 0 !important; }
pre.out { background: var(--code-bg); border: 1px solid var(--line); border-radius: 10px; padding: 8px 12px; margin: 4px 0; font: 14px/1.5 var(--mono);
  white-space: pre-wrap; overflow-x: auto; min-height: 1.5em; }
textarea, input[type=text], input[type=password], input[type=date], input[type=number], select {
  width: 100%; border: 1.5px solid var(--line); background: var(--card); border-radius: 11px; padding: 10px 12px; outline: none;
}
textarea:focus, input:focus, select:focus { border-color: var(--pri); }
textarea.mono, input.mono { font-family: var(--mono); font-size: 14px; }
textarea { resize: vertical; min-height: 46px; }
.blank { display: flex; align-items: center; gap: 8px; margin-bottom: 8px; }
.blank label { font-weight: 800; color: var(--pri); min-width: 26px; }
.opts { display: grid; gap: 8px; margin: 8px 0 12px; }
.opt { text-align: left; border: 1.5px solid var(--line); background: var(--card); border-radius: 12px; padding: 11px 14px; cursor: pointer; font-size: 15px; }
.opt.sel { border-color: var(--pri); background: var(--pri-soft); }
.opt.right { border-color: var(--ok); background: var(--ok-soft); }
.opt.wrong { border-color: var(--bad); background: var(--bad-soft); }
.opt .k { font-weight: 800; margin-right: 6px; color: var(--ink3); }
.verdict { border-radius: 12px; padding: 12px 14px; margin: 12px 0; font-weight: 700; display: flex; align-items: center; gap: 10px; }
.verdict.ok { background: var(--ok-soft); color: var(--ok); }
.verdict.bad { background: var(--bad-soft); color: var(--bad); }
.verdict.warn { background: var(--warn-soft); color: var(--warn); }
.verdict .big { font-size: 22px; }
.cmp { display: grid; grid-template-columns: 1fr 1fr; gap: 8px; }
.cmp h4 { margin: 0 0 2px; font-size: 12px; color: var(--ink3); font-weight: 600; }
@media (max-width: 520px) { .cmp { grid-template-columns: 1fr; } }
details.sec { border: 1px solid var(--line); border-radius: 12px; margin: 8px 0; background: var(--card); }
details.sec > summary { cursor: pointer; padding: 10px 14px; font-weight: 700; list-style: none; display: flex; align-items: center; gap: 8px; }
details.sec > summary::-webkit-details-marker { display: none; }
details.sec > summary::after { content: "▾"; margin-left: auto; color: var(--ink3); transition: transform .15s; }
details.sec:not([open]) > summary::after { transform: rotate(-90deg); }
details.sec > div { padding: 0 14px 12px; }
.md { font-size: 14.5px; }
.md p { margin: 6px 0; }
.md ul, .md ol { padding-left: 20px; margin: 6px 0; }
.md li { margin: 3px 0; }
.md code { font-family: var(--mono); font-size: 13px; background: var(--soft); padding: 1px 5px; border-radius: 5px; }
.md pre { background: var(--code-bg); border: 1px solid var(--line); border-radius: 10px; padding: 8px 12px; overflow-x: auto; }
.md pre code { background: none; padding: 0; font-size: 13px; line-height: 1.55; }
.tw { overflow-x: auto; margin: 8px 0; }
.md table { border-collapse: collapse; font-size: 13px; min-width: 100%; }
.md th, .md td { border: 1px solid var(--line); padding: 5px 8px; text-align: left; vertical-align: top; }
.md th { background: var(--soft); white-space: nowrap; }
.md h1 { font-size: 20px; } .md h2 { font-size: 17px; margin-top: 22px; border-bottom: 1px solid var(--line); padding-bottom: 4px; } .md h3 { font-size: 15px; }
.md blockquote { margin: 8px 0; padding: 6px 12px; border-left: 3px solid var(--pri); background: var(--pri-soft); border-radius: 0 8px 8px 0; }
.fig { background: #fff; border-radius: 10px; border: 1px solid var(--line); padding: 6px; margin: 8px 0 12px; text-align: center; }
.fig img { display: block; margin: 0 auto; max-height: 420px; }
.stickybar { position: sticky; bottom: calc(66px + env(safe-area-inset-bottom, 0px)); z-index: 5; display: flex; gap: 8px; padding: 8px 0 4px;
  background: linear-gradient(to top, var(--bg) 70%, transparent); }
.kbd { font-size: 11px; color: var(--ink3); }
.verify li { font-size: 13px; }

/* 요약/목록 */
.list .it { display: block; padding: 10px 2px; border-bottom: 1px solid var(--line); color: var(--ink); }
.list .it:last-child { border-bottom: 0; }
.term-row { padding: 9px 2px; border-bottom: 1px solid var(--line); }
.term-row:last-child { border-bottom: 0; }
.term-row .t { font-weight: 700; }
.term-row .t small { font-weight: 400; color: var(--ink3); margin-left: 4px; }
.hide-terms .term-row .t { filter: blur(6px); cursor: pointer; }
.hide-terms .term-row .t.show { filter: none; }
.dots { display: flex; gap: 3px; }
.dots i { width: 7px; height: 7px; border-radius: 50%; background: var(--soft); }
.dots i.on { background: var(--ok); }
.tabs { display: flex; gap: 6px; overflow-x: auto; margin-bottom: 10px; padding-bottom: 2px; }
.tabs button { flex: none; border: 1px solid var(--line); background: var(--card); border-radius: 99px; padding: 6px 12px; font-size: 13px; cursor: pointer; }
.tabs button.on { background: var(--pri); color: #fff; border-color: var(--pri); }

/* 모의고사 */
.navgrid { display: grid; grid-template-columns: repeat(10, 1fr); gap: 5px; margin: 8px 0; }
.navgrid button { aspect-ratio: 1; border: 1px solid var(--line); border-radius: 8px; background: var(--card); font-size: 12px; cursor: pointer; padding: 0; }
.navgrid button.done { background: var(--pri-soft); border-color: var(--pri); color: var(--pri); font-weight: 700; }
.navgrid button.cur { outline: 2px solid var(--pri); }
.navgrid button.r { background: var(--ok-soft); border-color: var(--ok); color: var(--ok); }
.navgrid button.w { background: var(--bad-soft); border-color: var(--bad); color: var(--bad); }
.timer { font-variant-numeric: tabular-nums; font-weight: 700; }
.score { font-size: 42px; font-weight: 800; text-align: center; line-height: 1.1; }

/* 기타 */
.modal { position: fixed; inset: 0; z-index: 50; background: rgba(10,12,20,.5); display: flex; align-items: flex-end; justify-content: center; }
.modal > div { background: var(--card); width: 100%; max-width: 760px; max-height: 92vh; overflow: auto; border-radius: 18px 18px 0 0;
  padding: 16px 16px calc(16px + env(safe-area-inset-bottom, 0px)); }
@media (min-width: 700px) { .modal { align-items: center; } .modal > div { border-radius: 18px; } }
.toast { position: fixed; left: 50%; transform: translateX(-50%); bottom: calc(80px + env(safe-area-inset-bottom, 0px)); z-index: 60;
  background: var(--ink); color: var(--bg); padding: 9px 16px; border-radius: 99px; font-size: 14px; box-shadow: 0 4px 20px rgba(0,0,0,.25); max-width: 90vw; }
.login { max-width: 380px; margin: 12vh auto 0; text-align: center; }
.login h1 { font-size: 24px; margin: 0 0 4px; }
.empty { text-align: center; color: var(--ink3); padding: 30px 10px; }
.spin { display: inline-block; width: 14px; height: 14px; border: 2px solid currentColor; border-right-color: transparent; border-radius: 50%; animation: sp .8s linear infinite; }
@keyframes sp { to { transform: rotate(360deg); } }
.hl-mark { background: color-mix(in srgb, var(--warn) 30%, transparent); border-radius: 3px; }
.cal { display: grid; grid-template-columns: repeat(15, 1fr); gap: 3px; margin-top: 8px; }
.cal i { aspect-ratio: 1; border-radius: 3px; background: var(--soft); }
.cal i.l1 { background: color-mix(in srgb, var(--pri) 30%, var(--soft)); }
.cal i.l2 { background: color-mix(in srgb, var(--pri) 60%, var(--soft)); }
.cal i.l3 { background: var(--pri); }
table.plain { width: 100%; border-collapse: collapse; font-size: 13px; }
table.plain td, table.plain th { padding: 6px 4px; border-bottom: 1px solid var(--line); text-align: left; vertical-align: top; }