:root{
  --bg:#fbfaf7; --fg:#1f2328; --muted:#5b6370; --line:#dcd8cf;
  --accent:#1f6f5c; --accent-weak:#e4f1ec; --warn:#8a4b00; --warn-bg:#fff4e2;
  --card:#ffffff; --maxw:760px;
}
*{box-sizing:border-box}
html{-webkit-text-size-adjust:100%}
body{margin:0;background:var(--bg);color:var(--fg);
  font-family:system-ui,-apple-system,"Hiragino Sans","Hiragino Kaku Gothic ProN","Noto Sans JP",Meiryo,sans-serif;
  line-height:1.8;font-size:16px;overflow-wrap:anywhere}
a{color:var(--accent)}
a:focus-visible,button:focus-visible,input:focus-visible{outline:3px solid #f0b400;outline-offset:2px}
.wrap{max-width:var(--maxw);margin:0 auto;padding:0 16px}
header.site{background:var(--card);border-bottom:1px solid var(--line)}
header.site .wrap{display:flex;flex-wrap:wrap;align-items:center;justify-content:space-between;gap:8px;padding-top:10px;padding-bottom:10px}
.logo{font-weight:700;text-decoration:none;color:var(--fg);font-size:1.05rem}
nav.gnav ul{list-style:none;margin:0;padding:0;display:flex;flex-wrap:wrap;gap:4px 14px;font-size:.92rem}
nav.gnav a{display:inline-block;padding:6px 2px;min-height:32px;line-height:20px}
.skip{position:absolute;left:8px;top:-60px;background:var(--card);border:2px solid var(--accent);padding:8px 12px;z-index:10;border-radius:6px}
.skip:focus{top:8px}
main{padding:24px 0 40px}
h1{font-size:1.55rem;line-height:1.45;margin:.2em 0 .5em}
h2{font-size:1.25rem;line-height:1.5;margin:2em 0 .6em;padding-bottom:.25em;border-bottom:2px solid var(--accent-weak)}
h3{font-size:1.06rem;margin:1.5em 0 .4em}
.lead{color:var(--muted)}
.meta{font-size:.85rem;color:var(--muted)}
.breadcrumb{font-size:.85rem;color:var(--muted);margin-bottom:8px}
.box{background:var(--card);border:1px solid var(--line);border-radius:8px;padding:14px 16px;margin:16px 0}
.note{background:var(--warn-bg);border-left:4px solid var(--warn);padding:10px 14px;margin:16px 0;font-size:.95rem}
.point{background:var(--accent-weak);border-radius:8px;padding:12px 16px;margin:16px 0}
.cards{display:grid;grid-template-columns:1fr;gap:12px;padding:0;list-style:none}
@media(min-width:640px){.cards{grid-template-columns:1fr 1fr}}
.cards li{background:var(--card);border:1px solid var(--line);border-radius:8px;padding:14px 16px}
.cards a{font-weight:700}
.cards p{margin:.3em 0 0;font-size:.92rem;color:var(--muted)}
.table-wrap{overflow-x:auto;margin:12px 0}
table{border-collapse:collapse;width:100%;min-width:480px;background:var(--card);font-size:.93rem}
th,td{border:1px solid var(--line);padding:8px 10px;text-align:left;vertical-align:top}
th{background:#f1efe9}
.formula{font-family:ui-monospace,Menlo,monospace;background:#f1efe9;padding:8px 12px;border-radius:6px;display:block;margin:8px 0}
.sources{font-size:.88rem}
.sources li{margin-bottom:.4em}
/* calculator */
.calc label{display:block;font-weight:600;margin-top:10px}
.calc input[type=number],.calc input[type=text]{width:100%;max-width:100%;font-size:1rem;padding:8px;border:1px solid #b9b4a8;border-radius:6px}
.calc .row{display:grid;grid-template-columns:1fr 84px 84px 40px;gap:6px;align-items:end;margin-top:8px}
.calc .row input{padding:7px 6px}
.calc .row>label{margin-top:0}
@media(max-width:520px){.calc .row{grid-template-columns:1fr 1fr 40px;padding-top:8px;border-top:1px dashed var(--line)}.calc .row>label:first-child{grid-column:1/-1}}
.calc .row .lbl{font-size:.78rem;color:var(--muted);display:block;font-weight:400}
.calc button{font-size:.95rem;padding:8px 14px;border-radius:6px;border:1px solid var(--accent);background:var(--card);color:var(--accent);cursor:pointer}
.calc button.primary{background:var(--accent);color:#fff}
.calc button.del{padding:6px 0;width:40px;border-color:#b9b4a8;color:var(--muted)}
.result{margin-top:14px;padding:12px 14px;border-radius:8px;background:var(--accent-weak)}
.result strong{font-size:1.15rem}
.result .meta strong,.result ul{font-size:inherit}
.result ul{margin:.3em 0;padding-left:1.2em}
.pr-notice{display:none;font-size:.85rem;background:#f1efe9;padding:6px 10px;border-radius:4px}
footer.site{border-top:1px solid var(--line);background:var(--card);font-size:.88rem;color:var(--muted)}
footer.site .wrap{padding-top:16px;padding-bottom:24px}
footer.site ul{list-style:none;padding:0;margin:0 0 8px;display:flex;flex-wrap:wrap;gap:4px 16px}