:root {
  --bg: #f7f8fa;
  --surface: #ffffff;
  --text: #1c2230;
  --muted: #5d6576;
  --line: #e3e6ec;
  --brand: #1f6feb;
  --brand-soft: #e8f0fe;
  --accent: #0f9d76;
  --warn-bg: #fff8e6;
  --warn-line: #f1d48a;
  --radius: 14px;
  --shadow: 0 1px 2px rgba(20, 30, 50, .06), 0 4px 16px rgba(20, 30, 50, .05);
}
@media (prefers-color-scheme: dark) {
  :root {
    --bg: #12151b; --surface: #1a1e26; --text: #e7eaf0; --muted: #9aa3b4;
    --line: #2b313d; --brand: #5b9bff; --brand-soft: #1c2a42; --accent: #36c79c;
    --warn-bg: #2a2416; --warn-line: #5c4b1f;
    --shadow: none;
  }
}
* { box-sizing: border-box; }
html { -webkit-text-size-adjust: 100%; }
body {
  margin: 0; background: var(--bg); color: var(--text);
  font-family: "Pretendard", -apple-system, BlinkMacSystemFont, "Apple SD Gothic Neo", "Malgun Gothic", "Noto Sans KR", sans-serif;
  line-height: 1.75; font-size: 16px; word-break: keep-all; overflow-wrap: anywhere;
}
a { color: var(--brand); text-decoration: none; }
a:hover { text-decoration: underline; }
.wrap { max-width: 960px; margin: 0 auto; padding: 0 16px; }

/* header */
.site-header { background: var(--surface); border-bottom: 1px solid var(--line); position: sticky; top: 0; z-index: 10; }
.header-inner { display: flex; align-items: center; justify-content: space-between; gap: 12px; min-height: 60px; flex-wrap: wrap; }
.logo { font-weight: 800; font-size: 1.15rem; color: var(--text); display: flex; align-items: center; gap: 8px; }
.logo:hover { text-decoration: none; }
.logo-mark { display: inline-grid; place-items: center; width: 30px; height: 30px; border-radius: 8px; background: var(--brand); color: #fff; font-size: .95rem; }
.nav { display: flex; gap: 4px; flex-wrap: wrap; }
.nav a { color: var(--muted); padding: 6px 10px; border-radius: 8px; font-size: .95rem; }
.nav a:hover { background: var(--brand-soft); color: var(--brand); text-decoration: none; }

.main { padding-top: 28px; padding-bottom: 56px; min-height: 60vh; }
h1 { font-size: 1.7rem; line-height: 1.35; margin: 0 0 12px; letter-spacing: -0.02em; }
h2 { font-size: 1.3rem; margin: 40px 0 12px; letter-spacing: -0.01em; }
h3 { font-size: 1.08rem; margin: 24px 0 8px; }
.lead { color: var(--muted); font-size: 1.05rem; margin: 0 0 24px; }
.crumb { font-size: .88rem; color: var(--muted); margin: 0 0 8px; }
.small { font-size: .85rem; color: var(--muted); }

/* hero */
.hero { background: linear-gradient(135deg, var(--brand-soft), var(--surface)); border: 1px solid var(--line); border-radius: var(--radius); padding: 32px 24px; margin-bottom: 32px; }
.hero h1 { font-size: 1.9rem; }
.hero p { color: var(--muted); margin: 0; }

/* cards */
.grid { display: grid; grid-template-columns: repeat(auto-fill, minmax(260px, 1fr)); gap: 14px; }
.card { display: block; background: var(--surface); border: 1px solid var(--line); border-radius: var(--radius); padding: 18px; color: var(--text); box-shadow: var(--shadow); transition: border-color .15s, transform .15s; }
.card:hover { border-color: var(--brand); text-decoration: none; transform: translateY(-2px); }
.card h3 { margin: 6px 0 6px; font-size: 1.05rem; }
.card p { margin: 0; color: var(--muted); font-size: .92rem; line-height: 1.6; }
.card .icon { font-size: 1.6rem; }
.tag { display: inline-block; font-size: .78rem; font-weight: 600; color: var(--brand); background: var(--brand-soft); padding: 2px 8px; border-radius: 999px; }
.section-head { display: flex; justify-content: space-between; align-items: baseline; margin-top: 40px; }
.section-head h2 { margin: 0 0 12px; }

.chips { display: flex; flex-wrap: wrap; gap: 8px; margin-bottom: 18px; }
.chip { border: 1px solid var(--line); background: var(--surface); color: var(--muted); padding: 6px 14px; border-radius: 999px; cursor: pointer; font: inherit; font-size: .9rem; }
.chip.active { background: var(--brand); color: #fff; border-color: var(--brand); }

/* calculator */
.calc { background: var(--surface); border: 1px solid var(--line); border-radius: var(--radius); padding: 22px; box-shadow: var(--shadow); margin: 20px 0 28px; }
.form-grid { display: grid; grid-template-columns: repeat(auto-fit, minmax(220px, 1fr)); gap: 14px 18px; }
.field label { display: block; font-weight: 600; font-size: .92rem; margin-bottom: 6px; }
.field .hint { display: block; font-weight: 400; color: var(--muted); font-size: .8rem; margin-top: 4px; line-height: 1.5; }
.input-wrap { position: relative; }
.input-wrap .unit { position: absolute; right: 12px; top: 50%; transform: translateY(-50%); color: var(--muted); font-size: .9rem; pointer-events: none; }
input[type=text], input[type=number], input[type=date], select {
  width: 100%; padding: 11px 44px 11px 12px; border: 1px solid var(--line); border-radius: 10px;
  font: inherit; font-size: 1rem; background: var(--bg); color: var(--text);
}
select, input[type=date] { padding-right: 12px; }
input:focus, select:focus { outline: 2px solid var(--brand); outline-offset: 1px; border-color: transparent; }
.check { display: flex; align-items: center; gap: 8px; font-size: .95rem; padding-top: 6px; }
.btn { display: inline-block; margin-top: 18px; padding: 12px 22px; border: 0; border-radius: 10px; background: var(--brand); color: #fff; font: inherit; font-weight: 700; cursor: pointer; width: 100%; font-size: 1rem; }
.btn:hover { filter: brightness(1.07); }
.btn.secondary { background: var(--surface); color: var(--brand); border: 1px solid var(--brand); width: auto; padding: 8px 14px; font-size: .9rem; }
.result { margin-top: 22px; border-top: 1px dashed var(--line); padding-top: 18px; display: none; }
.result.show { display: block; }
.result-main { background: var(--brand-soft); border-radius: 12px; padding: 18px; text-align: center; }
.result-main .label { color: var(--muted); font-size: .92rem; }
.result-main .value { font-size: 2rem; font-weight: 800; color: var(--brand); letter-spacing: -0.02em; line-height: 1.3; }
.result-main .sub { font-size: .9rem; color: var(--muted); }
.error { color: #d93025; font-size: .92rem; margin-top: 12px; }

table { width: 100%; border-collapse: collapse; margin: 14px 0; font-size: .93rem; background: var(--surface); }
th, td { border-bottom: 1px solid var(--line); padding: 9px 10px; text-align: left; }
th { background: var(--bg); font-weight: 600; }
td.num, th.num { text-align: right; font-variant-numeric: tabular-nums; }
tr.total td { font-weight: 700; border-top: 2px solid var(--text); }
.table-scroll { overflow-x: auto; -webkit-overflow-scrolling: touch; }
.table-scroll table { min-width: 480px; }

/* article */
.post { background: var(--surface); border: 1px solid var(--line); border-radius: var(--radius); padding: 28px 24px; }
.post-meta { color: var(--muted); font-size: .88rem; margin: 0 0 24px; padding-bottom: 16px; border-bottom: 1px solid var(--line); }
.post p, .content p { margin: 0 0 16px; }
.post ul, .post ol, .content ul, .content ol { padding-left: 22px; margin: 0 0 16px; }
.post li, .content li { margin-bottom: 6px; }
.toc { background: var(--bg); border: 1px solid var(--line); border-radius: 10px; padding: 14px 18px; margin: 0 0 24px; font-size: .95rem; }
.toc strong { display: block; margin-bottom: 4px; }
.toc ol { margin: 0; }
.notice, .tip { background: var(--warn-bg); border: 1px solid var(--warn-line); border-radius: 10px; padding: 14px 16px; font-size: .92rem; margin: 20px 0; }
.tip { background: var(--brand-soft); border-color: transparent; }
.cta { display: block; background: var(--brand); color: #fff; border-radius: 12px; padding: 16px 18px; margin: 24px 0; font-weight: 700; }
.cta:hover { text-decoration: none; filter: brightness(1.07); }
.cta span { display: block; font-weight: 400; font-size: .9rem; opacity: .9; }
.related { margin-top: 32px; }
.sitemap li { margin-bottom: 4px; }

/* footer */
.site-footer { border-top: 1px solid var(--line); background: var(--surface); padding: 28px 0; }
.footer-links { display: flex; flex-wrap: wrap; gap: 6px 18px; margin: 0 0 10px; font-size: .92rem; }
.footer-links a { color: var(--text); }

@media (max-width: 600px) {
  h1, .hero h1 { font-size: 1.45rem; }
  .post { padding: 20px 16px; }
  .calc { padding: 18px 14px; }
  .result-main .value { font-size: 1.65rem; }
  .header-inner { padding: 8px 0; }
}