:root{
  color-scheme: light;
  --bg:#F8FAFC; --surface:#FFFFFF; --surface-2:#F1F5F9; --border:#E2E8F0;
  --text:#0F172A; --muted:#64748B; --accent:#2563EB; --accent-soft:rgba(37,99,235,.08);
  --ok:#059669; --warn:#D97706; --warn-soft:rgba(217,119,6,.08); --info-soft:rgba(37,99,235,.06);
  --radius:12px;
}
@media (prefers-color-scheme: dark){
  :root{
    color-scheme: dark;
    --bg:#0F172A; --surface:#111C33; --surface-2:#18233B; --border:#243350;
    --text:#E7ECF5; --muted:#8FA1BD; --accent:#0EA5E9; --accent-soft:rgba(14,165,233,.10);
    --ok:#10B981; --warn:#F59E0B; --warn-soft:rgba(245,158,11,.10); --info-soft:rgba(14,165,233,.08);
  }
}
*{box-sizing:border-box}
html{-webkit-text-size-adjust:100%}
body{margin:0;background:var(--bg);color:var(--text);
  font-family:"Plus Jakarta Sans",-apple-system,BlinkMacSystemFont,"Hiragino Sans","Noto Sans JP","Yu Gothic UI",sans-serif;
  line-height:1.8;-webkit-font-smoothing:antialiased}
a{color:var(--accent);text-decoration:none}
a:hover{text-decoration:underline}
.mono,code{font-family:"JetBrains Mono",ui-monospace,Menlo,Consolas,monospace}
.wrap{max-width:760px;margin:0 auto;padding:0 16px}

/* header */
.site-head{border-bottom:1px solid var(--border);background:var(--bg);position:sticky;top:0;z-index:5}
.site-head .wrap{display:flex;align-items:center;gap:14px;height:56px}
.brand{font-weight:800;color:var(--text);letter-spacing:-.01em;white-space:nowrap}
.brand:hover{text-decoration:none}
.brand small{font-family:"JetBrains Mono",monospace;font-weight:700;font-size:10px;color:var(--accent);
  border:1px solid var(--accent);border-radius:5px;padding:1px 5px;margin-left:6px;vertical-align:2px}
.course-chip{font-family:"JetBrains Mono",monospace;font-size:12px;font-weight:700;color:var(--muted);
  border-left:1px solid var(--border);padding-left:12px;white-space:nowrap}
.course-chip:hover{color:var(--text);text-decoration:none}
@media (max-width:400px){.course-chip{display:none}}
.nav{display:flex;gap:14px;margin-left:auto;align-items:center;font-size:13.5px;font-weight:600}
.nav a{color:var(--muted)} .nav a:hover{color:var(--text);text-decoration:none}
.nav .cta{color:#fff;background:var(--accent);padding:7px 12px;border-radius:9px}
@media (prefers-color-scheme: dark){.nav .cta{color:#03141F}}
.nav .cta:hover{opacity:.9}
.nav a{white-space:nowrap}
@media (max-width:520px){.nav .hide-sm{display:none}}
@media (max-width:400px){.nav .hide-xs{display:none}.nav .cta{padding:7px 10px}}

/* content */
main{padding:28px 0 56px}
.eyebrow{font-family:"JetBrains Mono",monospace;font-size:11px;letter-spacing:.12em;color:var(--muted);text-transform:uppercase}
h1{font-size:26px;line-height:1.35;margin:6px 0 14px;letter-spacing:-.01em}
h2{font-size:18px;margin:32px 0 10px;padding-top:4px}
h3{font-size:15px;margin:22px 0 6px}
p{margin:0 0 14px}
.lead{font-size:15.5px;color:var(--muted)}
.crumbs{font-size:12px;color:var(--muted);margin-bottom:10px}
.crumbs a{color:var(--muted)}
.card{background:var(--surface);border:1px solid var(--border);border-radius:var(--radius);padding:18px}
.grid{display:grid;gap:10px}
@media (min-width:620px){.grid.two{grid-template-columns:1fr 1fr}.grid.three{grid-template-columns:1fr 1fr 1fr}}
.btn{display:inline-flex;align-items:center;justify-content:center;gap:8px;font-weight:700;border-radius:10px;
  padding:13px 20px;background:var(--accent);color:#fff;font-size:15px}
@media (prefers-color-scheme: dark){.btn{color:#03141F}}
.btn:hover{text-decoration:none;opacity:.92}
.btn.ghost{background:transparent;color:var(--text);border:1px solid var(--border)}
.beta{display:flex;gap:12px;align-items:flex-start;border:1px solid var(--accent);background:var(--accent-soft);
  border-radius:var(--radius);padding:14px 16px;margin:18px 0}
.tag{font-family:"JetBrains Mono",monospace;font-size:10.5px;font-weight:700;border:1px solid currentColor;border-radius:6px;
  padding:1px 6px;color:var(--accent);white-space:nowrap}
.muted{color:var(--muted)}
.small{font-size:12.5px}

/* hero */
.hero{padding:18px 0 8px}
.hero h1{font-size:30px}
.nw{display:inline-block}
.hero .actions{display:flex;gap:10px;flex-wrap:wrap;margin-top:18px}
.stats{display:grid;grid-template-columns:repeat(3,1fr);gap:8px;margin:22px 0}
.stat{background:var(--surface);border:1px solid var(--border);border-radius:var(--radius);padding:12px}
.stat b{display:block;font-family:"JetBrains Mono",monospace;font-size:22px}
.stat span{font-size:11.5px;color:var(--muted)}
.feature h3{margin:0 0 4px}
.feature p{margin:0;font-size:13.5px;color:var(--muted)}

/* courses (brand top) */
.course{display:block;color:var(--text)}
.course:hover{text-decoration:none;border-color:var(--accent)}
.course .head{display:flex;align-items:center;gap:8px;margin-bottom:4px}
.course .name{font-weight:800;font-size:17px}
.course .ver{font-family:"JetBrains Mono",monospace;font-size:12px;color:var(--muted)}
.course .desc{font-size:13.5px;color:var(--muted);margin:0 0 10px}
.course .nums{display:flex;flex-wrap:wrap;gap:6px 16px;font-family:"JetBrains Mono",monospace;font-size:12px;color:var(--muted)}
.course .nums b{color:var(--text)}
.course.soon{border-style:dashed;background:transparent}
.tag.ok{color:var(--ok)} .tag.dim{color:var(--muted)}

/* glossary */
.az{display:flex;flex-wrap:wrap;gap:6px;margin:14px 0 6px}
.az a{font-family:"JetBrains Mono",monospace;font-weight:700;font-size:12px;border:1px solid var(--border);
  border-radius:7px;padding:4px 9px;color:var(--muted);background:var(--surface)}
.az a:hover{color:var(--accent);border-color:var(--accent);text-decoration:none}
.term-list{list-style:none;margin:0;padding:0;border-top:1px solid var(--border)}
.term-list li{border-bottom:1px solid var(--border)}
.term-list a{display:flex;gap:14px;padding:11px 4px;color:var(--text)}
.term-list a:hover{background:var(--surface);text-decoration:none}
.term-list .t{font-family:"JetBrains Mono",monospace;font-weight:700;min-width:92px}
.term-list .ja{font-size:13.5px}
.term-list .full{display:block;font-size:11.5px;color:var(--muted);font-family:"JetBrains Mono",monospace}
.letter{font-family:"JetBrains Mono",monospace;font-size:13px;color:var(--accent);margin:26px 0 6px;font-weight:700}
.term-h1{font-family:"JetBrains Mono",monospace;font-size:34px;color:var(--accent);margin-bottom:2px}
.term-full{font-family:"JetBrains Mono",monospace;color:var(--muted);font-size:13px}
.term-ja{font-weight:700;font-size:16px;margin:4px 0 16px}
.chips{display:flex;flex-wrap:wrap;gap:8px}
.chips a{font-family:"JetBrains Mono",monospace;font-weight:600;font-size:13px;border:1px solid var(--border);
  background:var(--surface-2);border-radius:8px;padding:5px 11px;color:var(--text)}
.chips a:hover{border-color:var(--accent);color:var(--accent);text-decoration:none}
.card-label,.note-label{display:block;font-family:"JetBrains Mono",monospace;font-size:10.5px;font-weight:700;
  letter-spacing:.1em;color:var(--accent);margin-bottom:4px}
.note.exam{font-size:14.5px}
.scenario p{font-size:14.5px}
.confuse{list-style:none;margin:0;padding:0;border-top:1px solid var(--border)}
.confuse li{display:flex;gap:14px;padding:11px 2px;border-bottom:1px solid var(--border);font-size:14px}
.confuse .ct{font-family:"JetBrains Mono",monospace;font-weight:700;min-width:110px;flex:none}
.confuse .cd{color:var(--muted)}
@media (max-width:520px){.confuse li{flex-direction:column;gap:2px}}
.badge{display:inline-block;font-size:10.5px;font-weight:700;color:var(--ok);border:1px solid var(--ok);border-radius:5px;
  padding:0 5px;margin-left:8px;vertical-align:1px}
.pager{display:flex;justify-content:space-between;gap:10px;margin-top:28px;font-size:13px}
.pager a{font-family:"JetBrains Mono",monospace}

/* tips */
.tip-list{display:grid;gap:10px}
.tip-list a{display:block;color:var(--text)}
.tip-list a:hover{text-decoration:none;border-color:var(--accent)}
.tip-list .cat{font-family:"JetBrains Mono",monospace;font-size:11px;color:var(--accent)}
.tip-list .ttl{font-weight:700;margin:2px 0}
.tip-list .meta{font-size:11.5px;color:var(--muted);font-family:"JetBrains Mono",monospace}
article ul,article ol{padding-left:22px;margin:0 0 14px}
article li{margin:4px 0}
ol.steps{list-style:none;counter-reset:s;padding:0}
ol.steps li{counter-increment:s;position:relative;padding:0 0 12px 38px}
ol.steps li::before{content:counter(s);position:absolute;left:0;top:1px;width:26px;height:26px;border-radius:99px;
  border:1px solid var(--accent);color:var(--accent);font:700 12px/24px "JetBrains Mono",monospace;text-align:center}
.note{border-left:3px solid var(--accent);background:var(--info-soft);border-radius:0 10px 10px 0;padding:12px 14px;margin:0 0 14px;font-size:14px}
.note.warn{border-color:var(--warn);background:var(--warn-soft)}
.table-wrap{overflow-x:auto;margin:0 0 16px}
table{border-collapse:collapse;width:100%;font-size:13.5px;background:var(--surface)}
th,td{border:1px solid var(--border);padding:8px 10px;text-align:left;vertical-align:top}
th{background:var(--surface-2);font-weight:700}

/* legal */
.draft{border:1px dashed var(--warn);background:var(--warn-soft);border-radius:10px;padding:12px 14px;font-size:13px;margin-bottom:18px}
.legal h2{font-size:16px}
.legal p,.legal li{font-size:14px}
.legal ol,.legal ul{padding-left:22px}

/* ad */
.ad{margin:32px 0}
.ad-label{font-family:"JetBrains Mono",monospace;font-size:10px;letter-spacing:.1em;color:var(--muted);margin-bottom:6px}
.ad-placeholder{height:250px;border:1px dashed var(--border);border-radius:10px;display:flex;align-items:center;
  justify-content:center;color:var(--muted);font-size:12px;font-family:"JetBrains Mono",monospace}

/* side rails (PC only) */
.rail{display:none}
@media (min-width:1260px) and (min-height:720px){
  .rail{display:block;position:fixed;top:84px;width:160px;z-index:1}
  .rail.left{left:calc(50% - 380px - 40px - 160px)}
  .rail.right{right:calc(50% - 380px - 40px - 160px)}
}
.rail-placeholder{width:160px;height:600px;border:1px dashed var(--border);border-radius:10px;display:flex;align-items:center;
  justify-content:center;text-align:center;color:var(--muted);font-size:12px;font-family:"JetBrains Mono",monospace;line-height:1.6}

/* app CTA */
.app-cta{display:flex;gap:14px;align-items:center;justify-content:space-between;flex-wrap:wrap;margin-top:28px}
.app-cta p{margin:0;font-size:13.5px}

/* footer */
.site-foot{border-top:1px solid var(--border);padding:24px 0 40px;font-size:12.5px;color:var(--muted)}
.site-foot nav{display:flex;flex-wrap:wrap;gap:6px 16px;margin-bottom:12px}
.site-foot nav a{color:var(--muted)}