/* 엔지니어 계산기 v3 - "벤치 계측기" 디자인
   색 토큰은 :root(라이트) 와 다크 두 블록으로 정의한다.
   시스템 설정은 prefers-color-scheme, 사용자 선택은 data-theme 속성이 우선한다. */

:root {
  color-scheme: light;
  --bg: #f2f6f7;
  --surface: #ffffff;
  --surface-2: #e9f0f2;
  --surface-3: #dbe5e9;
  --text: #101d24;
  --muted: #50626c;
  --border: #cfdbe0;
  --border-strong: #9fb4bd;
  --accent: #0a7e8c;
  --accent-ink: #ffffff;
  --accent-soft: #d9eef1;
  --ok: #17794a;
  --ok-bg: #dcf2e5;
  --warn: #8a5300;
  --warn-bg: #fff0d2;
  --crit: #a32117;
  --crit-bg: #fbe2de;
  --code-bg: #e9f0f2;
  --shadow: 0 1px 2px rgba(16, 29, 36, 0.06), 0 4px 14px rgba(16, 29, 36, 0.04);
  --radius: 10px;
  --mono: "JetBrains Mono", ui-monospace, Menlo, Consolas, monospace;
  --sans: Pretendard, -apple-system, BlinkMacSystemFont, "Apple SD Gothic Neo",
          "Malgun Gothic", "Noto Sans KR", sans-serif;
}

@media (prefers-color-scheme: dark) {
  :root:not([data-theme="light"]) {
    color-scheme: dark;
    --bg: #0b1419;
    --surface: #121d23;
    --surface-2: #1a2830;
    --surface-3: #223139;
    --text: #e2ecef;
    --muted: #93a6af;
    --border: #2a3c45;
    --border-strong: #4a606a;
    --accent: #3cc2d1;
    --accent-ink: #06282d;
    --accent-soft: #15343b;
    --ok: #5fd39a;
    --ok-bg: #13322a;
    --warn: #f2c264;
    --warn-bg: #3a2d12;
    --crit: #ff8a7d;
    --crit-bg: #3e1e1b;
    --code-bg: #1a2830;
    --shadow: 0 1px 2px rgba(0, 0, 0, 0.4);
  }
}

:root[data-theme="dark"] {
  color-scheme: dark;
  --bg: #0b1419;
  --surface: #121d23;
  --surface-2: #1a2830;
  --surface-3: #223139;
  --text: #e2ecef;
  --muted: #93a6af;
  --border: #2a3c45;
  --border-strong: #4a606a;
  --accent: #3cc2d1;
  --accent-ink: #06282d;
  --accent-soft: #15343b;
  --ok: #5fd39a;
  --ok-bg: #13322a;
  --warn: #f2c264;
  --warn-bg: #3a2d12;
  --crit: #ff8a7d;
  --crit-bg: #3e1e1b;
  --code-bg: #1a2830;
  --shadow: 0 1px 2px rgba(0, 0, 0, 0.4);
}

:root[data-theme="light"] {
  color-scheme: light;
}

* { box-sizing: border-box; }
[hidden] { display: none !important; }

html { -webkit-text-size-adjust: 100%; }

body {
  margin: 0;
  background: var(--bg);
  color: var(--text);
  font: 16px/1.6 var(--sans);
  word-break: keep-all;
  overflow-wrap: break-word;
}

a { color: var(--accent); }

:focus-visible {
  outline: 2px solid var(--accent);
  outline-offset: 2px;
}

.skip {
  position: absolute;
  left: -9999px;
  top: 8px;
  background: var(--surface);
  padding: 8px 12px;
  z-index: 50;
}
.skip:focus { left: 8px; }

.ico {
  width: 20px;
  height: 20px;
  fill: none;
  stroke: currentColor;
  stroke-width: 1.8;
  stroke-linecap: round;
  stroke-linejoin: round;
  flex: none;
}

/* ---------- 페이지 골격 ---------- */
.page {
  max-width: 1000px;
  margin: 0 auto;
  padding: 0 16px;
  min-width: 0;
}
.page > main { min-width: 0; }

/* ---------- 헤더 ---------- */
.site-header {
  position: relative;
  background: var(--surface);
  border-bottom: 1px solid var(--border);
}
.hdr {
  display: flex;
  align-items: center;
  gap: 10px;
  min-height: 56px;
  max-width: 1240px;
  margin: 0 auto;
  padding: 0 16px;
}
.brand {
  display: inline-flex;
  align-items: center;
  gap: 10px;
  font-weight: 700;
  color: var(--text);
  text-decoration: none;
  letter-spacing: -0.01em;
  white-space: nowrap;
}
.logo { width: 28px; height: 28px; color: var(--accent); flex: none; }
.hnav {
  display: none;
  margin-left: auto;
  gap: 16px;
  font-size: 0.92rem;
}
.hnav a { color: var(--muted); text-decoration: none; }
.hnav a:hover { color: var(--accent); }
.hdr-tools { margin-left: auto; display: flex; gap: 8px; align-items: center; }
.icon-btn {
  display: inline-flex;
  align-items: center;
  gap: 6px;
  min-height: 40px;
  padding: 0 10px;
  font: 0.88rem var(--sans);
  color: var(--text);
  background: var(--surface);
  border: 1px solid var(--border-strong);
  border-radius: 8px;
  cursor: pointer;
}
.icon-btn:hover { border-color: var(--accent); color: var(--accent); }
.icon-btn .theme-txt { white-space: nowrap; }
.menu-btn { display: inline-flex; }

.menu {
  display: none;
  position: absolute;
  left: 0;
  right: 0;
  top: 100%;
  z-index: 30;
  max-height: calc(100vh - 56px);
  overflow: auto;
  background: var(--surface);
  border-bottom: 1px solid var(--border);
  box-shadow: var(--shadow);
  padding: 12px 16px 20px;
}
.menu.open { display: block; }
.menu .grp { margin: 14px 0 0; }
.menu h3 {
  margin: 0 0 6px;
  font-size: 0.8rem;
  letter-spacing: 0.04em;
  color: var(--muted);
}
.menu ul { list-style: none; margin: 0; padding: 0; display: grid; gap: 2px; }
.menu a {
  display: block;
  padding: 10px 12px;
  border-radius: 8px;
  color: var(--text);
  text-decoration: none;
  min-height: 44px;
}
.menu a:hover, .menu a[aria-current="page"] { background: var(--accent-soft); color: var(--accent); }
.menu .extra { margin-top: 12px; padding-top: 12px; border-top: 1px solid var(--border); display: flex; gap: 16px; flex-wrap: wrap; }
.menu .extra a { padding: 6px 0; min-height: 0; color: var(--muted); }

/* ---------- 사이드바 (1100px 이상, 계산기 페이지) ---------- */
.side { display: none; }

@media (min-width: 1100px) {
  .page.has-side {
    display: grid;
    grid-template-columns: 232px minmax(0, 1fr);
    gap: 28px;
    max-width: 1240px;
    padding: 0 20px;
  }
  .side {
    display: block;
    position: sticky;
    top: 16px;
    align-self: start;
    max-height: calc(100vh - 32px);
    overflow: auto;
    padding: 20px 0;
  }
  .menu-btn { display: none; }
}

.side h2 {
  margin: 14px 0 6px;
  font-size: 0.76rem;
  letter-spacing: 0.06em;
  color: var(--muted);
  font-weight: 700;
}
.side h2:first-child { margin-top: 0; }
.side ul { list-style: none; margin: 0; padding: 0; display: grid; gap: 2px; }
.side a {
  display: block;
  padding: 7px 10px;
  border-radius: 7px;
  color: var(--text);
  text-decoration: none;
  font-size: 0.93rem;
}
.side a:hover { background: var(--surface-2); }
.side a[aria-current="page"] {
  background: var(--accent-soft);
  color: var(--accent);
  font-weight: 700;
  box-shadow: inset 3px 0 0 var(--accent);
}

/* ---------- 제목·설명 ---------- */
main { padding-bottom: 8px; }
h1 {
  font-size: 1.6rem;
  line-height: 1.3;
  margin: 14px 0 6px;
  letter-spacing: -0.01em;
}
h2 { font-size: 1.15rem; margin: 0 0 8px; }
h3 { font-size: 1rem; margin: 0 0 6px; }
.lead { color: var(--muted); margin: 0 0 8px; }

.crumb {
  font-size: 0.86rem;
  color: var(--muted);
  margin: 10px 0 0;
  display: flex;
  flex-wrap: wrap;
  gap: 4px 6px;
  align-items: center;
}
.crumb a { color: var(--muted); text-decoration: none; }
.crumb a:hover { color: var(--accent); text-decoration: underline; }
.crumb span.sep { color: var(--border-strong); }

.info {
  display: flex;
  gap: 8px;
  align-items: flex-start;
  margin: 8px 0 0;
  padding: 8px 12px;
  font-size: 0.88rem;
  color: var(--muted);
  background: var(--surface-2);
  border-radius: 8px;
}
.info .ico { width: 16px; height: 16px; margin-top: 3px; color: var(--accent); }
.info code { font-size: 0.9em; }

/* ---------- 계산 패널 ---------- */
.calc { display: grid; gap: 0; }

.panel {
  display: grid;
  gap: 16px;
  grid-template-columns: minmax(0, 1fr);
  min-width: 0;
  margin: 16px 0;
  padding: 18px;
  background: var(--surface);
  border: 1px solid var(--border);
  border-radius: var(--radius);
  box-shadow: var(--shadow);
}
.panel > h2 { grid-column: 1 / -1; margin: 0; color: var(--accent); font-size: 1.05rem; }
.panel > .note { grid-column: 1 / -1; margin: 0; color: var(--muted); font-size: 0.92rem; }
.panel > .schem { grid-column: 1 / -1; }
.fields { display: grid; gap: 12px; align-content: start; min-width: 0; }
.rcol { display: grid; gap: 10px; align-content: start; min-width: 0; }

@media (min-width: 760px) {
  .panel { grid-template-columns: minmax(0, 1fr) minmax(0, 1fr); }
  .rcol {
    position: sticky;
    top: 16px;
    align-self: start;
    max-height: calc(100vh - 32px);
    overflow: auto;
    padding-right: 2px;
  }
}

/* 결과 열 머리: 제목 + 도구 버튼 */
.out-head {
  display: flex;
  flex-wrap: wrap;
  align-items: center;
  justify-content: space-between;
  gap: 8px;
}
.out-title { margin: 0; font-size: 0.82rem; letter-spacing: 0.05em; color: var(--muted); font-weight: 700; }
.tools { display: flex; flex-wrap: wrap; gap: 6px; }
.btn {
  display: inline-flex;
  align-items: center;
  gap: 6px;
  min-height: 36px;
  padding: 0 10px;
  font: 0.86rem var(--sans);
  color: var(--text);
  background: var(--surface);
  border: 1px solid var(--border-strong);
  border-radius: 8px;
  cursor: pointer;
}
.btn .ico { width: 16px; height: 16px; }
.btn:hover { border-color: var(--accent); color: var(--accent); }

/* ---------- 회로도 ---------- */
.schem {
  background: var(--surface-2);
  border: 1px solid var(--line);
  border-radius: 8px;
  padding: 10px 12px;
}
svg.schem-svg {
  display: block;
  width: 100%;
  height: auto;
  margin: 0 auto;
  color: var(--text);
}
svg.schem-svg .wire { fill: none; stroke: currentColor; stroke-width: 1.7; stroke-linecap: round; stroke-linejoin: round; }
svg.schem-svg .thin { fill: none; stroke: currentColor; stroke-width: 1.3; stroke-linecap: round; }
svg.schem-svg .plate { stroke: currentColor; stroke-width: 2.4; stroke-linecap: round; }
svg.schem-svg .part { fill: var(--surface); stroke: currentColor; stroke-width: 1.7; stroke-linejoin: round; }
svg.schem-svg .part.opt { stroke: var(--muted); stroke-dasharray: 4 3; }
svg.schem-svg .solid { fill: currentColor; stroke: currentColor; stroke-width: 1; stroke-linejoin: round; }
svg.schem-svg .dot { fill: currentColor; }
svg.schem-svg .term { fill: var(--surface); stroke: currentColor; stroke-width: 1.6; }
svg.schem-svg .arrow { fill: var(--accent); }
svg.schem-svg text { dominant-baseline: auto; }
svg.schem-svg .sl { fill: var(--text); font: 600 13px var(--sans); }
svg.schem-svg .sv { fill: var(--accent); font: 600 12px var(--mono); font-variant-numeric: tabular-nums; }
svg.schem-svg .sn { fill: var(--muted); font: 600 10.5px var(--sans); letter-spacing: 0.02em; }
@media (max-width: 520px) {
  /* 좁은 화면에서는 회로도가 축소되므로 글자를 키워 실제 크기 10px 이상을 유지한다 */
  svg.schem-svg .sl { font-size: 16px; }
  svg.schem-svg .sv { font-size: 15px; }
  svg.schem-svg .sn { font-size: 13px; }
  .schem { padding: 8px 2px; margin-inline: -6px; }
}

/* ---------- 입력 필드 ---------- */
.field { display: block; min-width: 0; }
.fl {
  display: block;
  font-size: 0.9rem;
  color: var(--muted);
  margin-bottom: 4px;
  font-weight: 600;
}
.iw { display: flex; align-items: stretch; min-width: 0; }
.iw input,
.field > select {
  flex: 1 1 auto;
  width: 100%;
  min-width: 0;
  min-height: 44px;
  padding: 8px 12px;
  font: 16px var(--mono);
  font-variant-numeric: tabular-nums;
  color: var(--text);
  background: var(--surface-2);
  border: 1px solid var(--border);
  border-radius: 8px;
}
.iw input { border-radius: 8px 0 0 8px; }
.iw .unit {
  display: flex;
  align-items: center;
  padding: 0 10px;
  white-space: nowrap;
  font: 0.86rem var(--mono);
  color: var(--muted);
  background: var(--surface-3);
  border: 1px solid var(--border);
  border-left: 0;
  border-radius: 0 8px 8px 0;
}
.iw input:focus,
.field > select:focus {
  outline: 2px solid var(--accent);
  outline-offset: 2px;
}
.field.bad .iw input,
.field.bad > select { border-color: var(--crit); box-shadow: inset 0 0 0 1px var(--crit); }
.ferr {
  display: block;
  margin-top: 4px;
  font-size: 0.84rem;
  color: var(--crit);
  font-weight: 600;
}
.field.bad .iw .unit { border-color: var(--crit); }

.seg-ctl { display: flex; gap: 0; border: 1px solid var(--border-strong); border-radius: 8px; overflow: hidden; }
.seg-ctl label { flex: 1 1 0; }
.seg-ctl input { position: absolute; opacity: 0; pointer-events: none; }
.seg-ctl span {
  display: flex;
  align-items: center;
  justify-content: center;
  min-height: 44px;
  padding: 0 8px;
  font-size: 0.92rem;
  cursor: pointer;
  color: var(--muted);
  background: var(--surface-2);
}
.seg-ctl input:checked + span { background: var(--accent); color: var(--accent-ink); font-weight: 700; }
.seg-ctl input:focus-visible + span { outline: 2px solid var(--accent); outline-offset: -4px; }

details.opt {
  border-top: 1px dashed var(--border);
  padding-top: 10px;
  margin-top: 4px;
}
details.opt summary {
  cursor: pointer;
  color: var(--accent);
  font-weight: 700;
  min-height: 44px;
  display: flex;
  align-items: center;
}
details.opt .fields { margin-top: 8px; }
details.opt .note { margin: 4px 0 8px; color: var(--muted); font-size: 0.9rem; }

/* ---------- 결과: 판독창 (readout) ---------- */
.readout {
  display: grid;
  gap: 12px;
  padding: 14px 16px;
  background: var(--surface-2);
  border-radius: var(--radius);
  border-left: 4px solid var(--accent);
}
.ro-item { display: grid; gap: 2px; min-width: 0; }
.ro-label { font-size: 0.86rem; color: var(--muted); font-weight: 600; }
.ro-val {
  display: flex;
  flex-wrap: wrap;
  align-items: baseline;
  gap: 4px 8px;
  font: 600 2rem/1.15 var(--mono);
  font-variant-numeric: tabular-nums;
  color: var(--text);
  overflow-wrap: anywhere;
}
.ro-unit { font: 600 1rem var(--mono); color: var(--muted); }
.ro-text { font: 600 1.35rem/1.3 var(--mono); }
.ro-item .chip { justify-self: start; margin-top: 4px; }

/* ---------- 결과 목록 ---------- */
.res-list { margin: 0; display: grid; gap: 8px; }
.res-row {
  display: flex;
  flex-wrap: wrap;
  align-items: center;
  justify-content: space-between;
  gap: 4px 10px;
  padding: 10px 12px;
  background: var(--surface-2);
  border-radius: 8px;
}
.res-name { margin: 0; color: var(--muted); font-size: 0.9rem; min-width: 0; }
.res-val {
  margin: 0 0 0 auto;
  font: 600 1.02rem var(--mono);
  font-variant-numeric: tabular-nums;
  color: var(--text);
  text-align: right;
  overflow-wrap: anywhere;
}
.res-text { font-family: var(--sans); font-size: 0.98rem; }
.res-sub {
  margin: 12px 0 0;
  font-size: 0.9rem;
  color: var(--accent);
  border-bottom: 1px solid var(--border);
  padding-bottom: 2px;
}

/* 상태 칩 (색 + 글자) */
.chip {
  display: inline-flex;
  align-items: center;
  gap: 4px;
  padding: 2px 9px;
  border-radius: 999px;
  font: 600 0.78rem var(--sans);
  border: 1px solid currentColor;
  white-space: nowrap;
}
.chip.ok { color: var(--ok); background: var(--ok-bg); }
.chip.warn { color: var(--warn); background: var(--warn-bg); }
.chip.crit { color: var(--crit); background: var(--crit-bg); }
.res-row .chip { margin-left: 4px; }

/* 게이지 (열 온도 등) */
.gauge { margin: 2px 2px 6px; }
.g-track {
  position: relative;
  height: 12px;
  border-radius: 6px;
  background: var(--surface-3);
}
.g-fill { height: 100%; border-radius: 6px; background: var(--ok); }
.g-fill.warn { background: var(--warn); }
.g-fill.crit { background: var(--crit); }
.g-mark {
  position: absolute;
  top: -5px;
  bottom: -5px;
  width: 2px;
  margin-left: -1px;
  background: var(--crit);
}
.g-scale {
  display: flex;
  justify-content: space-between;
  font: 0.74rem var(--mono);
  color: var(--muted);
  margin-top: 4px;
}

/* 손실 분포 막대 */
.stack { display: grid; gap: 8px; margin: 2px 0 4px; }
.stack-bar {
  display: flex;
  height: 20px;
  border-radius: 6px;
  overflow: hidden;
  background: var(--surface-3);
}
.seg { height: 100%; display: block; min-width: 0; }
.seg.s1 { background: var(--accent); }
.seg.s2 { background: var(--warn); }
.seg.s3 { background: var(--ok); }
.seg.s4 { background: var(--crit); }
.seg.s5 { background: var(--muted); }
.legend { list-style: none; margin: 0; padding: 0; display: grid; gap: 4px; }
.legend li {
  display: grid;
  grid-template-columns: 12px minmax(0, 1fr) auto;
  gap: 8px;
  align-items: center;
  font-size: 0.9rem;
}
.legend .sw { width: 12px; height: 12px; border-radius: 3px; display: inline-block; }
.legend .sw.s1 { background: var(--accent); }
.legend .sw.s2 { background: var(--warn); }
.legend .sw.s3 { background: var(--ok); }
.legend .sw.s4 { background: var(--crit); }
.legend .sw.s5 { background: var(--muted); }
.legend .lg-val { font: 0.86rem var(--mono); color: var(--muted); font-variant-numeric: tabular-nums; }

.msg {
  padding: 10px 12px;
  border-radius: 8px;
  font-size: 0.93rem;
}
.msg.warn { background: var(--warn-bg); color: var(--warn); }
.msg.err { background: var(--crit-bg); color: var(--crit); font-weight: 600; }

/* 파형 */
.wave-wrap { margin: 6px 0 0; }
.wave-cap { margin: 4px 0 0; font-size: 0.84rem; color: var(--muted); }
svg.wave { display: block; width: 100%; height: auto; }
svg.wave .ax { stroke: var(--border-strong); stroke-width: 1; }
svg.wave .grid { stroke: var(--border); stroke-width: 1; opacity: 0.7; }
svg.wave .vgrid { stroke: var(--border); stroke-width: 1; stroke-dasharray: 2 3; }
svg.wave .dash { stroke: var(--muted); stroke-width: 1; stroke-dasharray: 4 3; }
svg.wave .w { fill: none; stroke: var(--accent); stroke-width: 2; stroke-linejoin: round; }
svg.wave text { fill: var(--muted); font: 12px var(--mono); }
svg.wave text.lbl { fill: var(--text); }
svg.wave text.note { fill: var(--warn); font: 12px var(--sans); }

.tbl-wrap { overflow-x: auto; margin: 4px 0; }
.tbl {
  width: 100%;
  border-collapse: collapse;
  font-size: 0.86rem;
  font-variant-numeric: tabular-nums;
}
.tbl th, .tbl td {
  padding: 6px 4px;
  text-align: right;
  border-bottom: 1px solid var(--border);
  vertical-align: bottom;
}
.tbl th { color: var(--muted); font-weight: 600; font-size: 0.78rem; line-height: 1.3; }
.tbl td { font-family: var(--mono); font-size: 0.8rem; }
.tbl th:first-child, .tbl td:first-child { text-align: left; }

/* ---------- 모바일 하단 판독 바 ---------- */
.mbar {
  display: none;
  position: fixed;
  left: 0;
  right: 0;
  bottom: 0;
  z-index: 25;
  align-items: center;
  gap: 12px;
  min-height: 56px;
  padding: 8px 16px calc(8px + env(safe-area-inset-bottom));
  background: var(--surface);
  border: 0;
  border-top: 1px solid var(--border-strong);
  box-shadow: 0 -4px 16px rgba(0, 0, 0, 0.08);
  text-align: left;
  color: var(--text);
  font: inherit;
  cursor: pointer;
}
.mbar.show { display: flex; }
.mb-item { display: grid; gap: 0; min-width: 0; flex: 1 1 0; }
.mb-l { font-size: 0.74rem; color: var(--muted); font-weight: 600; white-space: nowrap; overflow: hidden; text-overflow: ellipsis; }
.mb-v { font: 600 1.05rem var(--mono); font-variant-numeric: tabular-nums; white-space: nowrap; }
.mb-err { color: var(--crit); font-weight: 700; font-size: 0.92rem; }
.mbar-go { font-size: 0.8rem; color: var(--accent); font-weight: 700; white-space: nowrap; }

@media (max-width: 759px) {
  body.has-mbar { padding-bottom: calc(72px + env(safe-area-inset-bottom)); }
  .ro-val { font-size: 1.6rem; }
  .ro-text { font-size: 1.2rem; }
  .hdr { gap: 8px; }
}
@media (min-width: 760px) {
  .mbar { display: none !important; }
  .hnav { display: flex; }
  .hdr-tools { margin-left: 0; }
  .ro-val { font-size: 2rem; }
  h1 { font-size: 1.9rem; }
}

/* 토스트 */
.toast {
  position: fixed;
  left: 50%;
  bottom: 24px;
  transform: translateX(-50%) translateY(12px);
  padding: 8px 16px;
  color: var(--surface);
  background: var(--text);
  border-radius: 8px;
  font-size: 0.92rem;
  opacity: 0;
  pointer-events: none;
  transition: opacity 0.15s, transform 0.15s;
  z-index: 60;
}
.toast.show { opacity: 1; transform: translateX(-50%) translateY(0); }

/* ---------- 광고 자리 (비어 있으면 높이 0) ---------- */
.ad-slot { margin: 16px 0; }
.ad-slot:empty { display: none; }

/* ---------- 관련 계산기 ---------- */
.related { margin: 16px 0 0; }
.related h2 { font-size: 1rem; margin: 0 0 8px; color: var(--muted); }
.rel-list {
  display: grid;
  gap: 10px;
  grid-template-columns: repeat(auto-fill, minmax(min(100%, 200px), 1fr));
  list-style: none;
  margin: 0;
  padding: 0;
}
.rel-list a {
  display: block;
  min-height: 56px;
  padding: 12px 14px;
  background: var(--surface);
  border: 1px solid var(--border);
  border-radius: 10px;
  color: var(--text);
  text-decoration: none;
  font-weight: 600;
  font-size: 0.95rem;
}
.rel-list a:hover { border-color: var(--accent); color: var(--accent); }

/* ---------- 설명 카드 ---------- */
.content {
  margin: 16px 0 8px;
  padding: 20px;
  background: var(--surface);
  border: 1px solid var(--border);
  border-radius: var(--radius);
  box-shadow: var(--shadow);
}
.content h2 {
  margin: 24px 0 8px;
  padding-bottom: 4px;
  border-bottom: 1px solid var(--border);
  color: var(--text);
  scroll-margin-top: 16px;
}
.content h2:first-child { margin-top: 0; }
.content p { margin: 8px 0; }
.content ul { margin: 8px 0; padding-left: 20px; }
.content li { margin: 4px 0; }
.toc {
  margin: 0 0 16px;
  padding: 12px 16px;
  background: var(--surface-2);
  border-radius: 8px;
  font-size: 0.92rem;
}
.toc strong { display: block; margin-bottom: 4px; }
.toc ol { margin: 0; padding-left: 20px; display: grid; gap: 2px; }
.formula {
  margin: 8px 0;
  padding: 10px 12px;
  background: var(--code-bg);
  border-radius: 8px;
  font: 0.92rem/1.75 var(--mono);
  overflow-x: auto;
}
code {
  font-family: var(--mono);
  font-size: 0.92em;
  background: var(--code-bg);
  padding: 1px 5px;
  border-radius: 4px;
  overflow-wrap: anywhere;
}
.formula code { background: none; padding: 0; }

.faq details {
  margin: 8px 0;
  padding: 10px 14px;
  background: var(--surface);
  border: 1px solid var(--border);
  border-radius: 8px;
}
.faq summary {
  cursor: pointer;
  font-weight: 700;
  min-height: 36px;
  display: flex;
  align-items: center;
}
.faq details p { margin: 6px 0 2px; color: var(--text); }

/* ---------- 허브 ---------- */
.hero { margin: 18px 0 8px; }
.hero h1 { margin-top: 0; }
.search {
  position: relative;
  margin: 14px 0 6px;
}
.search input {
  width: 100%;
  min-height: 48px;
  padding: 10px 14px 10px 42px;
  font: 16px var(--sans);
  color: var(--text);
  background: var(--surface);
  border: 1px solid var(--border-strong);
  border-radius: 10px;
}
.search input:focus { outline: 2px solid var(--accent); outline-offset: 2px; }
.search .ico {
  position: absolute;
  left: 13px;
  top: 14px;
  color: var(--muted);
  width: 20px;
  height: 20px;
}
.search .kbd {
  position: absolute;
  right: 12px;
  top: 13px;
  font: 0.75rem var(--mono);
  color: var(--muted);
  border: 1px solid var(--border-strong);
  border-radius: 5px;
  padding: 1px 6px;
}
.none { color: var(--muted); padding: 16px 0; margin: 0; }

.recent { margin: 14px 0 0; }
.recent h2 { font-size: 0.82rem; color: var(--muted); letter-spacing: 0.04em; margin: 0 0 6px; }
.recent-list { display: flex; flex-wrap: wrap; gap: 8px; }
.recent-chip {
  display: inline-flex;
  align-items: center;
  min-height: 36px;
  padding: 0 12px;
  border: 1px solid var(--border-strong);
  border-radius: 999px;
  color: var(--text);
  text-decoration: none;
  font-size: 0.9rem;
  background: var(--surface);
}
.recent-chip:hover { border-color: var(--accent); color: var(--accent); }

.cat { margin: 22px 0 0; scroll-margin-top: 16px; }
.cat h2 {
  display: flex;
  align-items: baseline;
  gap: 8px;
  font-size: 1.02rem;
  margin: 0 0 10px;
}
.cat h2 small { font-size: 0.8rem; color: var(--muted); font-weight: 600; }
.cards {
  display: grid;
  gap: 12px;
  grid-template-columns: repeat(auto-fill, minmax(min(100%, 240px), 1fr));
  margin: 0;
  padding: 0;
  list-style: none;
}
.card {
  position: relative;
  display: flex;
  flex-direction: column;
  gap: 6px;
  height: 100%;
  min-height: 132px;
  padding: 16px;
  background: var(--surface);
  border: 1px solid var(--border);
  border-radius: var(--radius);
  box-shadow: var(--shadow);
  color: inherit;
  text-decoration: none;
}
.card:hover { border-color: var(--accent); }
.card:hover h3 { color: var(--accent); }
.card-ico {
  display: inline-flex;
  width: 36px;
  height: 36px;
  align-items: center;
  justify-content: center;
  border-radius: 8px;
  background: var(--accent-soft);
  color: var(--accent);
}
.card-ico .ico { width: 22px; height: 22px; stroke-width: 1.6; }
.card h3 { font-size: 1.02rem; margin: 2px 0 0; color: var(--text); }
.card p { margin: 0; color: var(--muted); font-size: 0.92rem; line-height: 1.5; }
.badge {
  display: inline-block;
  padding: 1px 8px;
  font-size: 0.72rem;
  font-weight: 700;
  vertical-align: middle;
  color: var(--accent);
  background: var(--accent-soft);
  border: 1px solid var(--accent);
  border-radius: 999px;
  white-space: nowrap;
}
.card .badge { align-self: flex-start; margin-top: auto; }
.note-box {
  margin: 16px 0;
  padding: 12px 14px;
  background: var(--accent-soft);
  border-radius: var(--radius);
  font-size: 0.95rem;
}

/* ---------- 색띠 (저항 컬러 코드) ---------- */
.sw-grid { display: grid; gap: 10px; grid-template-columns: repeat(auto-fill, minmax(min(100%, 120px), 1fr)); }
.band-pick { display: grid; gap: 6px; }
.band-pick .bp-title { font-size: 0.86rem; color: var(--muted); font-weight: 600; }
.sw-row { display: flex; flex-wrap: wrap; gap: 6px; }
.sw-btn {
  display: inline-flex;
  align-items: center;
  gap: 6px;
  min-height: 36px;
  padding: 3px 8px 3px 4px;
  font: 0.82rem var(--sans);
  color: var(--text);
  background: var(--surface);
  border: 1px solid var(--border-strong);
  border-radius: 8px;
  cursor: pointer;
}
.sw-btn[aria-pressed="true"] { border: 2px solid var(--accent); padding: 2px 7px 2px 3px; }
.sw-chip { width: 22px; height: 22px; border-radius: 5px; border: 1px solid rgba(0, 0, 0, 0.35); display: inline-block; flex: none; }
.tabs { display: flex; gap: 0; border: 1px solid var(--border-strong); border-radius: 8px; overflow: hidden; }
.tab {
  flex: 1 1 0;
  min-height: 44px;
  font: 0.92rem var(--sans);
  color: var(--muted);
  background: var(--surface-2);
  border: 0;
  cursor: pointer;
}
.tab[aria-selected="true"] { background: var(--accent); color: var(--accent-ink); font-weight: 700; }
.resistor-svg { display: block; width: 100%; max-width: 420px; height: auto; margin: 4px auto; }
.resistor-svg .body { fill: #e8d3a6; stroke: #2b2118; stroke-width: 2; }
.resistor-svg .lead { stroke: #8c8c8c; stroke-width: 3; fill: none; }

/* ---------- 푸터 ---------- */
.site-footer {
  margin-top: 32px;
  padding: 24px 0 32px;
  border-top: 1px solid var(--border);
  background: var(--surface);
  color: var(--muted);
  font-size: 0.9rem;
}
.site-footer .fcols { display: grid; gap: 18px; grid-template-columns: 1fr; }
.site-footer h2 { font-size: 0.8rem; color: var(--muted); letter-spacing: 0.04em; margin: 0 0 6px; }
.site-footer ul { list-style: none; margin: 0; padding: 0; display: grid; gap: 4px; }
.site-footer a { color: var(--text); text-decoration: none; }
.site-footer a:hover { color: var(--accent); text-decoration: underline; }
.site-footer .copy { margin: 18px 0 0; font-size: 0.85rem; }
@media (min-width: 760px) {
  .site-footer .fcols { grid-template-columns: repeat(4, minmax(0, 1fr)); }
}

@media (max-width: 480px) {
  .content { padding: 16px; }
  .panel { padding: 14px; }
  .brand span.name { font-size: 0.95rem; }
}

/* ---------- v4: 언어 전환 (헤더) · 언어 안내 막대 ---------- */
.lang {
  display: inline-flex; align-items: center; gap: 6px;
  font-size: 13px; color: var(--muted); white-space: nowrap;
  border: 1px solid var(--border); border-radius: 999px; padding: 4px 10px;
  background: var(--surface);
}
.lang a { color: var(--accent); text-decoration: none; font-weight: 600; }
.lang a:hover { text-decoration: underline; }
.lang .lcur { color: var(--text); font-weight: 600; }
.lang .lsep { color: var(--border-strong); }
@media (max-width: 759px) {
  .lang { font-size: 12px; padding: 3px 8px; }
}

.lang-bar {
  display: flex; align-items: center; gap: 10px; flex-wrap: wrap;
  min-height: 0; max-height: 44px; box-sizing: border-box;
  padding: 6px 16px; font-size: 14px;
  background: var(--accent-soft); color: var(--text);
  border-bottom: 1px solid var(--border);
}
.lang-bar .lb-text { flex: 1 1 auto; min-width: 0; }
.lang-bar .lb-go { color: var(--accent); font-weight: 600; white-space: nowrap; }
.lang-bar .lb-x {
  flex: 0 0 auto; width: 28px; height: 28px; border-radius: 6px;
  border: 1px solid var(--border-strong); background: var(--surface);
  color: var(--text); font-size: 16px; line-height: 1; cursor: pointer;
}
@media (max-width: 759px) {
  .lang-bar { flex-wrap: nowrap; font-size: 13px; padding: 4px 12px; }
  .lang-bar .lb-text { overflow: hidden; text-overflow: ellipsis; white-space: nowrap; }
}
/* 모바일에서는 헤더 대신 메뉴 안에 언어 전환을 둔다 (헤더 가로폭 보호) */
.menu .lang.lang-menu { margin: 10px 0 4px; }
@media (min-width: 760px) { .menu .lang.lang-menu { display: none; } }
@media (max-width: 759px) { .hdr-tools .lang { display: none; } }