:root{--bg:#f6f9fc;--card:#fff;--ink:#14213d;--muted:#5b6b82;--line:#dfe7f1;--brand:#2b7fd8;--brand-ink:#0d4f99;--sky:#a6daff;--sky2:#d9efff;--note:#fff7d6;--note-line:#f2d675;--radius:14px;--shadow:0 1px 2px rgba(20,33,61,.06),0 6px 20px rgba(20,33,61,.06);--hdr:56px}
@media (prefers-color-scheme:dark){:root{--bg:#0f1622;--card:#172133;--ink:#e8eef7;--muted:#9fb0c8;--line:#26344b;--brand:#6db3ff;--brand-ink:#a9d3ff;--sky:#1d3c5e;--sky2:#16304d;--note:#2a2614;--note-line:#6b5a1d;--shadow:none}}
*,*::before,*::after{box-sizing:border-box}
html{-webkit-text-size-adjust:100%;scroll-behavior:smooth;scroll-padding-top:calc(var(--hdr) + 12px)}
body{margin:0;background:var(--bg);color:var(--ink);font:16px/1.65 system-ui,-apple-system,"Segoe UI",Roboto,"Helvetica Neue",Arial,"Noto Sans",sans-serif}
a{color:var(--brand);text-decoration:none}a:hover{text-decoration:underline}
img{max-width:100%;height:auto}
.wrap{max-width:1120px;margin:0 auto;padding:0 18px}
.narrow{max-width:800px}
.wide{max-width:1360px}
h1,h2,h3{text-wrap:balance}
:lang(ja) :is(h1,h2,h3){word-break:auto-phrase}
/* header */
.hdr{position:sticky;top:0;z-index:50;height:var(--hdr);background:var(--card);border-bottom:1px solid var(--line)}
.hdr-in{display:flex;align-items:center;gap:14px;height:100%}
.logo{display:flex;align-items:center;gap:9px;font-weight:800;font-size:18px;color:var(--ink);white-space:nowrap}
.logo:hover{text-decoration:none}.logo img{border-radius:7px}
.nav{display:flex;gap:2px;margin-left:auto;align-items:center}
.nav a{padding:7px 10px;border-radius:9px;color:var(--ink);font-size:15px;font-weight:600;white-space:nowrap}
.nav a:hover,.nav a[aria-current=page]{background:var(--sky2);text-decoration:none}
.langs{position:relative}
.langs summary{list-style:none;cursor:pointer;padding:7px 10px;border:1px solid var(--line);border-radius:9px;font-size:14px;font-weight:700;white-space:nowrap}
.langs summary::-webkit-details-marker{display:none}
.langs-menu{position:absolute;right:0;top:calc(100% + 6px);background:var(--card);border:1px solid var(--line);border-radius:12px;box-shadow:var(--shadow);padding:6px;min-width:190px;display:grid;z-index:60}
.langs-menu a{padding:7px 10px;border-radius:8px;color:var(--ink);font-size:14px}
.langs-menu a:hover,.langs-menu a[aria-current=true]{background:var(--sky2);text-decoration:none}
.burger{display:none;margin-left:auto;background:none;border:1px solid var(--line);border-radius:9px;color:var(--ink);font-size:20px;line-height:1;padding:7px 10px;cursor:pointer}
@media (max-width:1100px){
 .burger{display:block}
 .nav{display:none;position:absolute;left:0;right:0;top:var(--hdr);flex-direction:column;align-items:stretch;background:var(--card);border-bottom:1px solid var(--line);padding:8px 18px 14px;margin:0;box-shadow:var(--shadow)}
 .nav.open{display:flex}
 .nav a{padding:11px 10px}
 .langs{order:3}
}
/* game */
.game{background:#000;position:relative}
.game iframe{display:block;width:100%;height:calc(100vh - var(--hdr) - 44px);height:calc(100svh - var(--hdr) - 44px);min-height:460px;border:0}
.game-bar{display:flex;justify-content:center;align-items:center;gap:16px;height:44px;background:var(--sky);font-weight:700;font-size:15px}
.game-bar a{color:var(--ink)}
/* hero */
.hero{background:linear-gradient(180deg,var(--sky2),transparent);padding:34px 0 18px}
.hero h1{font-size:clamp(28px,4.2vw,42px);line-height:1.15;margin:0 0 10px;letter-spacing:-.01em}
.hero p.lead{font-size:clamp(17px,2vw,19px);color:var(--muted);margin:0;max-width:760px}
.crumbs{font-size:14px;color:var(--muted);margin-bottom:10px}.crumbs a{color:var(--muted)}
/* article */
.article{padding-top:8px;padding-bottom:30px}
.article h2{font-size:clamp(22px,2.6vw,28px);line-height:1.25;margin:34px 0 12px;letter-spacing:-.01em}
.article h3{font-size:19px;margin:24px 0 8px}
.article p,.article li{font-size:17px}
.article ul,.article ol{padding-left:24px}
.article li{margin:5px 0}
.article table,.tbl{border-collapse:collapse;width:100%;margin:14px 0;background:var(--card);border-radius:12px;overflow:hidden;box-shadow:var(--shadow);font-size:16px}
.article th,.article td,.tbl th,.tbl td{border-bottom:1px solid var(--line);padding:9px 12px;text-align:left;vertical-align:top}
.article th,.tbl th{background:var(--sky2);font-weight:700}
.note{background:var(--note);border:1px solid var(--note-line);border-radius:12px;padding:14px 16px;margin:18px 0}
.note p:last-child{margin-bottom:0}.note p:first-child{margin-top:0}
.card{background:var(--card);border:1px solid var(--line);border-radius:var(--radius);box-shadow:var(--shadow)}
.ad{margin:22px auto;text-align:center;min-height:0}
/* cards grid */
.grid{display:grid;grid-template-columns:repeat(auto-fill,minmax(170px,1fr));gap:12px;margin:16px 0 8px}
.gcard{display:flex;align-items:center;gap:10px;padding:12px 14px;background:var(--card);border:1px solid var(--line);border-radius:12px;color:var(--ink);font-weight:700;box-shadow:var(--shadow)}
.gcard:hover{border-color:var(--brand);text-decoration:none}
.gcard .em{font-size:26px;line-height:1}
.gcard small{display:block;color:var(--muted);font-weight:500;font-size:13px}
.more{display:inline-block;margin:6px 0 0;font-weight:700}
.btn{display:inline-block;background:var(--brand);color:#fff;font-weight:800;padding:12px 22px;border-radius:12px;font-size:17px}
.btn:hover{text-decoration:none;filter:brightness(1.08)}
.cta{text-align:center;padding:26px 18px;margin:30px 0 10px;background:var(--sky2);border-radius:var(--radius)}
.cta h2{margin:0 0 6px}.cta p{margin:0 0 14px;color:var(--muted)}
.apps{display:flex;flex-wrap:wrap;gap:12px;margin:12px 0}
.apps img{height:52px;width:auto}
/* chips & steps (guides) */
.chip{display:inline-flex;align-items:center;gap:5px;padding:3px 10px;border:1px solid var(--line);border-radius:999px;background:var(--card);font-weight:700;font-size:15px;white-space:nowrap}
.chips{display:flex;flex-wrap:wrap;gap:8px;margin:10px 0}
.steps{list-style:none;padding:0!important;counter-reset:s;margin:14px 0}
.steps li{counter-increment:s;display:flex;flex-wrap:wrap;align-items:center;gap:8px;padding:12px 14px 12px 54px;position:relative;background:var(--card);border:1px solid var(--line);border-radius:12px;margin:8px 0!important}
.steps li::before{content:counter(s);position:absolute;left:12px;top:50%;transform:translateY(-50%);width:30px;height:30px;border-radius:50%;background:var(--sky);display:grid;place-items:center;font-weight:800;font-size:15px}
.steps .op{color:var(--muted);font-weight:800}
.steps .res{display:inline-flex;align-items:center;gap:8px}
.answer{background:var(--card);border:2px solid var(--sky);border-radius:var(--radius);padding:14px 16px;margin:16px 0;font-size:18px}
/* chart */
.chart-tools{display:flex;gap:10px;align-items:center;flex-wrap:wrap;margin:18px 0 10px}
.chart-tools input{flex:1;min-width:220px;padding:11px 14px;border:1px solid var(--line);border-radius:10px;font-size:16px;background:var(--card);color:var(--ink)}
.chart{overflow:auto;max-height:78vh;border:1px solid var(--line);border-radius:12px;background:var(--card)}
.chart table{border-collapse:separate;border-spacing:0;font-size:14px;min-width:900px;width:100%}
.chart th,.chart td{padding:7px 9px;border-bottom:1px solid var(--line);border-right:1px solid var(--line);white-space:nowrap;text-align:left}
.chart thead th{position:sticky;top:0;background:var(--sky2);z-index:2}
.chart tbody th{position:sticky;left:0;background:var(--card);z-index:1}
.chart thead th:first-child{left:0;z-index:3}
.chart td a{color:var(--ink);text-decoration:underline;text-decoration-color:var(--brand)}
/* footer */
.ftr{background:var(--card);border-top:1px solid var(--line);margin-top:40px;padding:30px 0 22px;font-size:15px;color:var(--muted)}
.ftr-cols{display:grid;grid-template-columns:2fr 1fr 1fr;gap:24px}
.ftr strong{color:var(--ink)}
.ftr nav{display:grid;gap:6px;align-content:start}
.ftr nav a{color:var(--ink)}
.ftr .disc{margin:22px 0 6px;font-size:14px}
.ftr .copy{margin:0;font-size:14px}
.ftr-langs{display:flex;flex-wrap:wrap;gap:4px 12px;margin-top:14px;font-size:14px}
.ftr-langs a{color:var(--muted)}
@media (max-width:760px){.ftr-cols{grid-template-columns:1fr 1fr}.ftr-cols>div:first-child{grid-column:1/-1}}
.sr{position:absolute;width:1px;height:1px;overflow:hidden;clip:rect(0 0 0 0);white-space:nowrap}
/* legal */
.legal h2{font-size:22px}.legal p,.legal li{font-size:16px}
.err{text-align:center;padding:60px 0}
.err .big{font-size:72px;line-height:1;margin:0 0 10px}