:root{
  --bg: #f3f9f9;
  --bg-soft: #f8fbfb;
  --paper: #e8eef0;
  --ink: #1c1f20;
  --ink-soft: #4f5658;
  --line: #d7dfe0;
  --line-soft: #e3e9ea;
  --stamp: #8c3a2c;
  --muted: #8b9598;
  --tag: #e9eef0;
}
*{ box-sizing: border-box; }
html{ scroll-behavior: smooth; }
body{
  margin:0;
  background: var(--bg);
  color: var(--ink);
  font-family: "Noto Sans JP", sans-serif;
  font-weight: 300;
  -webkit-font-smoothing: antialiased;
}
a{ color: inherit; text-decoration: none; }
.mincho{ font-family: "Shippori Mincho", serif; }
.mono{ font-family: "JetBrains Mono", monospace; }

/* ---------- header ---------- */
header{
  display:flex;
  align-items:center;
  justify-content:space-between;
  padding: 22px 48px;
  border-bottom: 1px solid var(--line-soft);
}
.brand{ display:flex; align-items:baseline; gap:16px; }
.brand h1{
  font-family:"Shippori Mincho", serif;
  font-size: 1.5rem;
  font-weight: 600;
  margin:0;
  letter-spacing: .04em;
}
.brand p{
  margin:0;
  font-size: .72rem;
  color: var(--muted);
  letter-spacing: .03em;
}
nav{ display:flex; align-items:center; gap:36px; }
nav a{
  font-size: .85rem;
  color: var(--ink-soft);
  position: relative;
  padding-bottom: 6px;
}
nav a.active{ color: var(--ink); }
nav a.active::after{
  content:"";
  position:absolute; left:0; right:0; bottom:0;
  height:1px; background: var(--ink);
}
.header-right{ display:flex; align-items:center; gap:22px; }
.header-right .divider{ color: var(--line); font-size:.8rem; }
.login{ font-size:.82rem; color: var(--ink-soft); }
.login.double{ color: var(--stamp); }
.expand{
  width:16px; height:16px;
  border: 1px solid var(--ink-soft);
  opacity:.6;
}

/* ---------- footer ---------- */
footer{
  border-top: 1px solid var(--line-soft);
  padding: 26px 48px;
  display:flex;
  justify-content:space-between;
  align-items:center;
  font-size: .76rem;
  color: var(--muted);
}
.footer-links{ display:flex; gap: 24px; }

/* ---------- shared: page header block (used on inner pages) ---------- */
.page-head{
  max-width: 1300px;
  margin: 0 auto;
  padding: 56px 40px 30px;
}
.breadcrumb{
  font-size: .78rem;
  color: var(--muted);
  margin-bottom: 20px;
}
.breadcrumb a{ color: var(--ink-soft); }
.breadcrumb a:hover{ text-decoration: underline; }
.page-head h2{
  font-family:"Shippori Mincho", serif;
  font-weight: 700;
  font-size: clamp(2rem, 4vw, 3rem);
  margin: 0 0 6px;
  letter-spacing: .02em;
}
.page-head .page-tag{
  font-family:"JetBrains Mono", monospace;
  font-size: .72rem;
  letter-spacing:.15em;
  color: var(--muted);
}
.page-lede{
  max-width: 40em;
  font-size: .9rem;
  color: var(--ink-soft);
  line-height: 1.95;
  margin-top: 18px;
}

@media (max-width: 1000px){
  header{ padding: 18px 20px; }
  nav{ display:none; }
  .page-head{ padding: 36px 20px 20px; }
  footer{ flex-direction:column; gap:12px; padding: 24px 20px; }
}