:root {
  --bg: #f6f7f9;
  --surface: #ffffff;
  --text: #16181d;
  --muted: #5b6270;
  --line: #dfe3ea;
  --accent: #1f6feb;
  --accent-soft: #e8f0fe;
  --good: #117a45;
  --good-soft: #e5f5ec;
  --bad: #b42318;
  --bad-soft: #fdecea;
  --radius: 14px;
}
@media (prefers-color-scheme: dark) {
  :root:not([data-theme="light"]) {
    --bg: #0f1115; --surface: #181b21; --text: #eceef2; --muted: #a3aab8; --line: #2a2f38;
    --accent: #6ea8ff; --accent-soft: #1b2a44; --good: #5fd08f; --good-soft: #13291d; --bad: #ff8a80; --bad-soft: #3a1714;
  }
}
:root[data-theme="dark"] {
  --bg: #0f1115; --surface: #181b21; --text: #eceef2; --muted: #a3aab8; --line: #2a2f38;
  --accent: #6ea8ff; --accent-soft: #1b2a44; --good: #5fd08f; --good-soft: #13291d; --bad: #ff8a80; --bad-soft: #3a1714;
}

* { box-sizing: border-box; }
html { -webkit-text-size-adjust: 100%; }
body {
  margin: 0; background: var(--bg); color: var(--text);
  font: 16px/1.6 -apple-system, BlinkMacSystemFont, "Apple SD Gothic Neo", "Pretendard", "Malgun Gothic", sans-serif;
  word-break: keep-all;
}
a { color: var(--accent); }
.top, main, .related, .foot { max-width: 680px; margin: 0 auto; padding: 0 16px; }
.top { display: flex; justify-content: space-between; align-items: center; height: 52px; }
.brand { font-weight: 700; color: var(--text); text-decoration: none; }
.blog { font-size: 14px; color: var(--muted); }
h1 { font-size: 26px; line-height: 1.3; margin: 8px 0 4px; }
h2 { font-size: 19px; margin: 32px 0 10px; }
.lead { color: var(--muted); margin: 0 0 16px; }
.updated { display: inline-block; font-size: 13px; padding: 0 8px; border-radius: 99px; background: var(--accent-soft); color: var(--accent); }

.calc { background: var(--surface); border: 1px solid var(--line); border-radius: var(--radius); padding: 18px 16px; }
.field { display: grid; gap: 6px; margin-bottom: 14px; }
.field > label, .field > .label { font-weight: 600; font-size: 15px; }
.hint { font-size: 13px; color: var(--muted); }
.row { display: grid; grid-template-columns: 1fr 1fr; gap: 12px; }
@media (max-width: 420px) { .row { grid-template-columns: 1fr; } }
.input-wrap { display: flex; align-items: center; border: 1px solid var(--line); border-radius: 10px; background: var(--bg); }
.input-wrap:focus-within { border-color: var(--accent); }
.input-wrap input, .input-wrap select {
  flex: 1; min-width: 0; border: 0; background: transparent; color: var(--text);
  font: inherit; font-size: 17px; padding: 11px 12px; outline: none;
}
.input-wrap .unit { padding-right: 12px; color: var(--muted); font-size: 15px; white-space: nowrap; }
.say { font-size: 13px; color: var(--accent); min-height: 1em; }
.seg { display: flex; flex-wrap: wrap; gap: 8px; }
.seg label {
  border: 1px solid var(--line); border-radius: 99px; padding: 7px 14px; cursor: pointer; font-size: 15px; background: var(--bg);
}
.seg input { position: absolute; opacity: 0; pointer-events: none; }
.seg label:has(input:checked) { border-color: var(--accent); background: var(--accent-soft); color: var(--accent); font-weight: 600; }
.seg label:has(input:focus-visible) { outline: 2px solid var(--accent); outline-offset: 2px; }

.result { display: block; margin-top: 16px; border-radius: var(--radius); padding: 16px; background: var(--accent-soft); }
.result.good { background: var(--good-soft); }
.result.bad { background: var(--bad-soft); }
.result .big { font-size: 28px; font-weight: 800; line-height: 1.25; margin: 2px 0 6px; }
.result.good .big { color: var(--good); }
.result.bad .big { color: var(--bad); }
.result dl { display: grid; grid-template-columns: auto auto; gap: 6px 12px; margin: 12px 0 0; font-size: 15px; }
.result dt { color: var(--muted); }
.result dd { margin: 0; text-align: right; font-variant-numeric: tabular-nums; font-weight: 600; }
.result .note { font-size: 13px; color: var(--muted); margin: 10px 0 0; }
.error { color: var(--bad); font-weight: 600; }

.explain p, .explain li { color: var(--text); }
.faq details { border-bottom: 1px solid var(--line); padding: 10px 0; }
.faq summary { cursor: pointer; font-weight: 600; }
.faq p { margin: 8px 0 0; color: var(--muted); }
.sources { font-size: 13px; color: var(--muted); margin-top: 24px; }
.cards { list-style: none; padding: 0; display: grid; gap: 12px; }
.card { display: grid; gap: 4px; padding: 16px; border: 1px solid var(--line); border-radius: var(--radius); background: var(--surface); text-decoration: none; color: var(--text); }
.card span { color: var(--muted); font-size: 14px; }
.related ul, .posts ul { padding-left: 18px; }
.foot { margin-top: 32px; padding-bottom: 40px; font-size: 13px; color: var(--muted); }