/* 레이아웃 개념: 도면 한 장. 위는 도면번호 줄, 가운데는 입력(왼쪽)과 표제란처럼 굵은 테두리의 결과(오른쪽), 아래는 계산 근거 문서. 좁은 화면에서는 한 줄로 쌓입니다. */
:root {
  --bg: #eef1f0;
  --grid: rgba(31, 90, 138, 0.06);
  --surface: #ffffff;
  --ink: #17201e;
  --muted: #55625e;
  --line: #c9d1ce;
  --accent: #1f5a8a;
  --accent-ink: #ffffff;
  --tint: #e2ebf3;
  --warn: #8a5300;
  --warn-bg: #fbefdc;
  --good: #1f6b45;
  --good-bg: #e1f1e7;

  --font-ui: "IBM Plex Sans KR", "Apple SD Gothic Neo", "Malgun Gothic", "Noto Sans KR", sans-serif;
  --font-num: "IBM Plex Mono", ui-monospace, "SFMono-Regular", Consolas, monospace;

  --s-1: 0.8125rem;
  --s0: 1rem;
  --s1: 1.1875rem;
  --s2: 1.5rem;
  --s3: 2rem;
}
@media (prefers-color-scheme: dark) {
  :root:not([data-theme="light"]) {
    --bg: #101615;
    --grid: rgba(125, 179, 224, 0.05);
    --surface: #171f1e;
    --ink: #e3e9e7;
    --muted: #96a39f;
    --line: #2d3836;
    --accent: #7db3e0;
    --accent-ink: #0d1a24;
    --tint: #1b2b38;
    --warn: #f0b867;
    --warn-bg: #33270f;
    --good: #7fd0a2;
    --good-bg: #13291d;
    color-scheme: dark;
  }
}
:root[data-theme="dark"] {
  --bg: #101615;
  --grid: rgba(125, 179, 224, 0.05);
  --surface: #171f1e;
  --ink: #e3e9e7;
  --muted: #96a39f;
  --line: #2d3836;
  --accent: #7db3e0;
  --accent-ink: #0d1a24;
  --tint: #1b2b38;
  --warn: #f0b867;
  --warn-bg: #33270f;
  --good: #7fd0a2;
  --good-bg: #13291d;
  color-scheme: dark;
}

*, *::before, *::after { box-sizing: border-box; }

body {
  margin: 0;
  background-color: var(--bg);
  background-image:
    linear-gradient(var(--grid) 1px, transparent 1px),
    linear-gradient(90deg, var(--grid) 1px, transparent 1px);
  background-size: 20px 20px;
  color: var(--ink);
  font-family: var(--font-ui);
  font-size: var(--s0);
  line-height: 1.65;
  -webkit-text-size-adjust: 100%;
}

a { color: var(--accent); text-underline-offset: 0.18em; }
a:focus-visible, button:focus-visible, input:focus-visible, select:focus-visible {
  outline: 2px solid var(--accent);
  outline-offset: 2px;
}

.wrap {
  max-width: 1080px;
  margin: 0 auto;
  padding-left: max(16px, env(safe-area-inset-left, 0px));
  padding-right: max(16px, env(safe-area-inset-right, 0px));
}

/* ---------- 머리글 ---------- */
.site-head { background: var(--surface); border-bottom: 2px solid var(--ink); }
.head-row {
  display: flex; flex-wrap: wrap; align-items: center; justify-content: space-between;
  gap: 8px 24px; padding-block: 12px;
}
.brand {
  display: inline-flex; align-items: center; gap: 10px;
  color: var(--ink); text-decoration: none; font-weight: 700; font-size: var(--s1); letter-spacing: -0.01em;
}
.brand-mark {
  width: 22px; height: 22px; border: 2px solid var(--ink); position: relative; flex: none;
}
.brand-mark::before, .brand-mark::after {
  content: ""; position: absolute; background: var(--accent);
}
.brand-mark::before { left: 50%; top: -5px; bottom: -5px; width: 2px; transform: translateX(-50%); }
.brand-mark::after { top: 50%; left: -5px; right: -5px; height: 2px; transform: translateY(-50%); }
.head-nav { display: flex; flex-wrap: wrap; align-items: center; gap: 8px 20px; font-size: var(--s-1); }
.head-nav .lang {
  width: auto; padding: 4px 8px; font-size: var(--s-1); cursor: pointer;
  background: var(--surface); color: var(--ink); border: 1px solid var(--line);
}
.head-nav a { color: var(--muted); text-decoration: none; }
.head-nav a:hover { color: var(--ink); }

/* ---------- 본문 공통 ---------- */
main { padding-block: 32px 56px; }
h1, h2, h3 { text-wrap: balance; line-height: 1.3; letter-spacing: -0.015em; }
h1 { font-size: var(--s3); margin: 6px 0 10px; }
h2 { font-size: var(--s2); margin: 40px 0 12px; }
h3 { font-size: var(--s1); margin: 24px 0 8px; }
p { margin: 0 0 14px; }
.lede { color: var(--muted); max-width: 62ch; font-size: var(--s1); }

.sheet-meta {
  display: flex; flex-wrap: wrap; gap: 0;
  font-family: var(--font-num); font-size: var(--s-1); letter-spacing: 0.04em;
  border: 1px solid var(--ink); width: fit-content; max-width: 100%;
}
.sheet-meta span { padding: 2px 10px; }
.sheet-meta span + span { border-left: 1px solid var(--ink); color: var(--muted); }

/* ---------- 계산 영역 ---------- */
.calc {
  display: grid; grid-template-columns: minmax(0, 1.15fr) minmax(0, 1fr);
  gap: 24px; margin-top: 24px; align-items: start;
}
@media (max-width: 760px) { .calc { grid-template-columns: minmax(0, 1fr); } }

.inputs {
  background: var(--surface); border: 1px solid var(--line); padding: 20px;
  display: grid; gap: 16px; margin: 0;
}
.field { display: grid; gap: 4px; min-width: 0; }
.field label { font-weight: 600; font-size: 0.9375rem; }
.field .hint { color: var(--muted); font-size: var(--s-1); margin: 0; }
.row2 { display: grid; grid-template-columns: repeat(2, minmax(0, 1fr)); gap: 16px; }
@media (max-width: 420px) { .row2 { grid-template-columns: minmax(0, 1fr); } }

.input-unit { display: flex; align-items: stretch; border: 1px solid var(--line); background: var(--bg); }
.input-unit:focus-within { border-color: var(--accent); }
.input-unit input { border: 0; outline: none; }
.input-unit span {
  display: flex; align-items: center; padding: 0 12px; flex: none;
  font-family: var(--font-num); font-size: var(--s-1); color: var(--muted);
  border-left: 1px solid var(--line);
}
input[type="number"], input[type="text"], input[type="search"], select {
  width: 100%; min-width: 0; padding: 10px 12px; font: inherit; color: var(--ink);
  background: var(--bg); border: 1px solid var(--line); border-radius: 0;
}
input[type="number"] { font-family: var(--font-num); font-variant-numeric: tabular-nums; }
.input-unit input[type="number"] { background: transparent; }
select { appearance: auto; }

.btn-link {
  justify-self: start; background: none; border: 0; padding: 0; font: inherit; font-size: var(--s-1);
  color: var(--accent); text-decoration: underline; text-underline-offset: 0.18em; cursor: pointer;
}

/* 표제란 */
.results { position: sticky; top: calc(env(safe-area-inset-top, 0px) + 16px); display: grid; gap: 12px; }
@media (max-width: 760px) { .results { position: static; } }
.titleblock {
  width: 100%; border-collapse: collapse; background: var(--surface);
  border: 2px solid var(--ink); font-variant-numeric: tabular-nums;
}
.titleblock caption {
  caption-side: top; text-align: left; font-family: var(--font-num); font-size: var(--s-1);
  letter-spacing: 0.08em; text-transform: uppercase; color: var(--muted); padding-bottom: 6px;
}
.titleblock th, .titleblock td { border: 1px solid var(--line); padding: 9px 12px; text-align: left; vertical-align: baseline; }
.titleblock th { font-weight: 500; color: var(--muted); font-size: 0.9375rem; width: 44%; }
.titleblock td { font-family: var(--font-num); font-size: var(--s1); font-weight: 500; overflow-wrap: anywhere; }
.titleblock td .u { font-size: var(--s-1); color: var(--muted); margin-left: 6px; font-weight: 400; }
.titleblock tr.key th { color: var(--ink); font-weight: 700; }
.titleblock tr.key td { background: var(--tint); font-size: var(--s2); }

.status { margin: 0; padding: 10px 12px; font-size: 0.9375rem; border-left: 3px solid transparent; }
.status:empty { display: none; }
.status.ok { background: var(--good-bg); color: var(--good); border-left-color: var(--good); }
.status.warn { background: var(--warn-bg); color: var(--warn); border-left-color: var(--warn); }

.copy {
  justify-self: start; font: inherit; font-size: var(--s-1); font-weight: 600; padding: 8px 14px;
  background: var(--accent); color: var(--accent-ink); border: 0; cursor: pointer;
}

/* ---------- 근거 문서 ---------- */
.doc { max-width: 68ch; }
.doc ul, .doc ol { padding-left: 1.25em; margin: 0 0 14px; }
.doc li { margin-bottom: 6px; }
.formula {
  overflow-x: auto; background: var(--surface); border: 1px solid var(--line); border-left: 3px solid var(--accent);
  padding: 12px 16px; margin: 0 0 14px; font-family: var(--font-num); font-size: 0.9375rem; line-height: 1.8;
  white-space: pre;
}
.table-wrap { overflow-x: auto; margin: 0 0 14px; }
.ref { border-collapse: collapse; font-size: 0.9375rem; font-variant-numeric: tabular-nums; min-width: 320px; }
.ref th, .ref td { border: 1px solid var(--line); padding: 6px 12px; text-align: left; }
.ref th { background: var(--surface); font-weight: 600; }
.ref td.n { font-family: var(--font-num); text-align: right; }
.note { color: var(--muted); font-size: 0.9375rem; }
.sources { font-size: 0.9375rem; }

/* ---------- 관련 계산기 / 목록 ---------- */
.tool-list { list-style: none; padding: 0; margin: 0; display: grid; grid-template-columns: repeat(auto-fill, minmax(min(100%, 300px), 1fr)); gap: 0; border-top: 1px solid var(--ink); border-left: 1px solid var(--ink); }
.tool-list li { border-right: 1px solid var(--ink); border-bottom: 1px solid var(--ink); background: var(--surface); }
.tool-list a { display: grid; gap: 4px; padding: 16px 18px; height: 100%; text-decoration: none; color: var(--ink); }
.tool-list a:hover { background: var(--tint); }
.tool-list .code { font-family: var(--font-num); font-size: var(--s-1); color: var(--accent); letter-spacing: 0.04em; }
.tool-list .name { font-weight: 700; font-size: var(--s1); }
.tool-list .desc { color: var(--muted); font-size: 0.9375rem; }

.related { margin-top: 48px; }
.related h2 { margin-top: 0; }

/* 홈 */
.hero { padding-block: 16px 8px; }
.hero h1 { font-size: clamp(2rem, 6vw, 3rem); margin-bottom: 12px; }
.filter { max-width: 420px; margin: 24px 0; }
.empty { color: var(--muted); }

/* ---------- 바닥글 ---------- */
.site-foot { border-top: 1px solid var(--line); background: var(--surface); }
.foot-row { display: flex; flex-wrap: wrap; gap: 8px 24px; justify-content: space-between; padding-block: 20px; color: var(--muted); font-size: var(--s-1); }
.foot-row nav { display: flex; gap: 16px; }
.foot-row a { color: var(--muted); }

@media (prefers-reduced-motion: reduce) { * { transition: none !important; } }