:root{
  --bg:#f4f6f8; --paper:#ffffff; --ink:#20242a; --muted:#5b6470;
  --line:#d4dae1; --accent:#2563eb; --accent-light:#dbeafe;
  --blue:#eaf4ff; --blue-border:#4385c5;
  --green:#ebf8ef; --green-border:#3b9559;
  --red:#fff0f0; --red-border:#ba4a4a;
  --orange:#fff4e5; --orange-border:#d68826;
  --purple:#f3efff; --purple-border:#7c6bc4;
  --code-bg:#f3f4f6;
}
*{box-sizing:border-box}
body{margin:0;background:var(--bg);color:var(--ink);font-family:-apple-system,BlinkMacSystemFont,"Segoe UI","Noto Sans JP",sans-serif;line-height:1.75}
a{color:var(--accent)}
a:hover{text-decoration:underline}

.site-header{background:var(--paper);border-bottom:1px solid var(--line)}
.site-brand{max-width:1340px;margin:0 auto;padding:14px 24px;font-weight:700}
.site-brand a{color:var(--ink);text-decoration:none}
.site-brand-sub{color:var(--muted);font-weight:400;font-size:.85rem}

.layout{max-width:1340px;margin:0 auto;padding:24px;display:grid;grid-template-columns:250px minmax(0,1fr);gap:24px;align-items:start}
.sidebar{position:sticky;top:24px;background:var(--paper);border:1px solid var(--line);border-radius:10px;padding:16px 14px;max-height:calc(100vh - 48px);overflow-y:auto}
.sidebar-title{font-size:.78rem;font-weight:700;color:var(--muted);letter-spacing:.08em;padding:2px 8px 10px;border-bottom:1px solid var(--line);margin-bottom:6px}
.site-nav{display:flex;flex-direction:column;align-items:stretch}
.nav-group{color:var(--muted);font-size:.72rem;letter-spacing:.06em;margin:14px 8px 4px;padding-top:10px;border-top:1px solid var(--line)}
.nav-group:first-child{border-top:none;margin-top:8px;padding-top:0}
.nav-link{display:block;color:var(--accent);text-decoration:none;font-size:.87rem;padding:5px 10px;border-radius:6px;line-height:1.45}
.nav-link:hover{background:var(--accent-light);text-decoration:none}
.nav-link.active{background:var(--accent);color:#fff;font-weight:600}

main.container{min-width:0;padding:40px 48px 56px;background:var(--paper);box-shadow:0 2px 16px #0001;border-radius:10px}

h1{font-size:1.9rem;line-height:1.4;margin:0 0 .4em;padding-bottom:.35em;border-bottom:2px solid var(--ink)}
h2{font-size:1.4rem;margin-top:2em;margin-bottom:.7em;padding-bottom:.25em;border-bottom:1px solid var(--line)}
h3{font-size:1.12rem;margin-top:1.7em}
h4{font-size:1rem;margin-top:1.5em;color:#374151}
p{margin:.7em 0}
.subtitle{color:var(--muted);font-size:1.02rem;margin:0 0 1.4em}
.lead{font-size:1.08rem;color:#374151;background:var(--accent-light);padding:1.1rem 1.2rem;border-radius:8px;border-left:4px solid var(--accent);margin:1.2em 0}
.small{font-size:.9rem;color:var(--muted)}
code,.mono{font-family:ui-monospace,SFMono-Regular,Consolas,monospace;background:var(--code-bg);padding:.08em .35em;border-radius:4px}
pre{background:#f6f7f8;border:1px solid #d8dde3;padding:14px;overflow:auto;line-height:1.5;border-radius:8px}
pre code{background:none;padding:0}

table{width:100%;border-collapse:collapse;margin:14px 0 22px;font-size:.95rem}
th,td{border:1px solid #aeb6bf;padding:8px 11px;vertical-align:top;text-align:left}
th{background:#f0f2f4}
tr:nth-child(even) td{background:#fafbfc}

svg{display:block;max-width:100%;height:auto;margin:14px 0 22px;background:#fff;border:1px solid #dfe3e7;border-radius:8px}

.note,.ok,.warn,.why,.box,.box-info,.box-ok,.box-warn,.box-danger,.ds-quote{padding:13px 16px;margin:16px 0;border-left:5px solid;border-radius:6px}
.note{background:var(--blue);border-color:var(--blue-border)}
.ok{background:var(--green);border-color:var(--green-border)}
.warn{background:var(--red);border-color:var(--red-border)}
.why{background:var(--orange);border-color:var(--orange-border)}
.box{background:#fff;border:1px solid var(--line);border-left:5px solid var(--accent)}
.box-info{background:#eff6ff;border-color:#93c5fd}
.box-ok{background:var(--green);border-color:#6ee7b7}
.box-warn{background:var(--orange);border-color:#fcd34d}
.box-danger{background:var(--red);border-color:#fca5a5}
.ds-quote{background:#f0fdf4;border:1px solid #bbf7d0;border-left:4px solid #22c55e;border-radius:0 8px 8px 0}
.ds-quote-title{font-weight:700;color:#15803d;margin-bottom:.5rem}

.toc{columns:2;column-gap:30px;background:#f7f8fa;padding:18px 24px;border-radius:8px;border:1px solid var(--line)}
.toc a{color:var(--accent);text-decoration:none}
.toc a:hover{text-decoration:underline}

.quiz details{border:1px solid #ccd2d9;border-radius:7px;padding:10px 14px;margin:9px 0;background:#fff}
.quiz details[open]{background:#fbfcfe}
.quiz summary{cursor:pointer;font-weight:600}

.diagram{background:#fff;border:1px solid var(--line);border-radius:12px;padding:1.2rem;margin:1.5rem 0;overflow-x:auto}
.diagram svg{border:none;margin:0}
.diagram-caption{text-align:center;font-size:.85rem;color:var(--muted);margin-top:.75rem}

.card{background:#fff;border:1px solid var(--line);border-radius:12px;padding:20px;margin:18px 0;box-shadow:0 1px 3px #0001}
.card-title{font-weight:700;margin-bottom:8px;display:flex;align-items:center;gap:8px}
.icon{font-size:1.2rem}
.big-number{font-size:2rem;font-weight:700;color:var(--accent);display:block;margin:4px 0}
.highlight-mark{background:#fef2f2;color:#b91c1c;padding:2px 6px;border-radius:4px;font-weight:700}
.highlight-space{background:#eff6ff;color:#1d4ed8;padding:2px 6px;border-radius:4px;font-weight:700}
.highlight-carrier{background:#fffbeb;color:#92400e;padding:2px 6px;border-radius:4px;font-weight:700}
.compare-grid{display:grid;grid-template-columns:1fr 1fr;gap:12px}
.compare-grid .card{margin:0}
.summary-box{background:linear-gradient(135deg,#dbeafe 0%,#ecfdf5 100%);border-radius:12px;padding:20px;margin:24px 0}
.summary-box h3{margin-top:0}

.step{display:flex;gap:1rem;align-items:flex-start;margin:1.5rem 0}
.step-num{flex-shrink:0;width:2.2rem;height:2.2rem;background:var(--accent);color:#fff;border-radius:50%;display:flex;align-items:center;justify-content:center;font-weight:700;font-size:1rem}
.step-body{flex:1}
.step-body h4{margin:0 0 .4rem;font-size:1.05rem}

ul,ol{padding-left:1.6rem}
li{margin:.35rem 0}
hr{border:none;border-top:1px solid var(--line);margin:2rem 0}

.site-footer{max-width:1040px;margin:0 auto 40px;padding:20px 24px;text-align:center;color:var(--muted);font-size:.85rem}

@media(max-width:900px){
  .layout{grid-template-columns:1fr;padding:16px}
  .sidebar{position:static;max-height:none;overflow:visible;margin-bottom:4px}
  main.container{padding:24px 18px}
  .site-brand{padding-left:16px;padding-right:16px}
  .toc{columns:1}
  .compare-grid{grid-template-columns:1fr}
}
@media print{
  body{background:#fff}
  .site-header,.site-footer,.sidebar{display:none}
  main.container{box-shadow:none;margin:0;max-width:none;padding:0;border-radius:0}
  svg,table,pre{break-inside:avoid}
  h2,h3{break-after:avoid}
  a{color:#000;text-decoration:none}
}