/* ============================================================
   Ryu Nakagawa — academic homepage
   Shared stylesheet (UTF-8)
   ============================================================ */

:root {
  --bg:          #f7f6f3;
  --surface:     #ffffff;
  --ink:         #1c2433;
  --ink-soft:    #475067;
  --muted:       #6b7280;
  --line:        #e3e1da;
  --accent:      #1f3a5f;   /* deep navy */
  --accent-2:    #2f6f8f;   /* teal-blue */
  --accent-soft: #eef2f6;
  --link:        #1f5fa6;
  --link-hover:  #123d70;
  --max:         1080px;
  --radius:      12px;
  --shadow:      0 1px 3px rgba(20,30,50,.06), 0 8px 24px rgba(20,30,50,.06);
  --serif: "Hiragino Mincho ProN", "Yu Mincho", "Times New Roman", Georgia, serif;
  --sans: -apple-system, BlinkMacSystemFont, "Segoe UI", "Hiragino Kaku Gothic ProN",
          "Yu Gothic", Meiryo, system-ui, sans-serif;
}

* { box-sizing: border-box; }

html { scroll-behavior: smooth; scroll-padding-top: 84px; }

body {
  margin: 0;
  font-family: var(--sans);
  color: var(--ink);
  background: var(--bg);
  line-height: 1.7;
  font-size: 16.5px;
  -webkit-font-smoothing: antialiased;
}

a { color: var(--link); text-decoration: none; }
a:hover { color: var(--link-hover); text-decoration: underline; }

/* ---------- Header / nav ---------- */
.site-header {
  position: sticky; top: 0; z-index: 50;
  background: rgba(255,255,255,.88);
  backdrop-filter: saturate(180%) blur(10px);
  border-bottom: 1px solid var(--line);
}
.nav {
  max-width: var(--max); margin: 0 auto;
  display: flex; align-items: center; justify-content: space-between;
  gap: 1rem; padding: .7rem 1.25rem;
}
.header-logo { height: 38px; width: auto; display: block; }
.logo-link { display: inline-flex; flex-direction: column; align-items: stretch; line-height: 1; }
.logo-link:hover { text-decoration: none; }
.logo-cap { display: block; text-align: center; font-size: 10pt; line-height: 1.1;
  margin-top: 2px; color: #010199; letter-spacing: 0; white-space: nowrap; }
.nav-links .nav-logo { margin-left: 1.1rem; padding: 0; }
.brand { font-family: var(--serif); font-weight: 600; font-size: 1.15rem;
  color: var(--ink); letter-spacing: .02em; white-space: nowrap; }
.brand:hover { text-decoration: none; color: var(--accent); }
.brand small { display:block; font-family: var(--sans); font-weight: 400;
  font-size: .68rem; color: var(--muted); letter-spacing: .04em; }
.nav-links { display: flex; flex-wrap: wrap; gap: .25rem; align-items: center; }
.nav-links a {
  color: var(--ink-soft); padding: .4rem .7rem; border-radius: 8px;
  font-size: .92rem; font-weight: 500;
}
.nav-links a:hover { background: var(--accent-soft); color: var(--accent); text-decoration: none; }
.nav-links a.active { color: var(--accent); background: var(--accent-soft); }
.nav-toggle { display:none; background:none; border:0; font-size:1.5rem; cursor:pointer; color:var(--ink); }

/* ---------- Layout ---------- */
main { max-width: var(--max); margin: 0 auto; padding: 0 1.25rem 4rem; }
section { scroll-margin-top: 84px; }

.hero {
  display: grid; grid-template-columns: 1fr auto; gap: 2.5rem;
  align-items: center;
  padding: 3rem 0 2.25rem;
  border-bottom: 1px solid var(--line);
}
.hero h1 { font-family: var(--serif); font-size: clamp(2rem, 4vw, 2.9rem);
  margin: 0 0 .35rem; letter-spacing: .01em; color: var(--ink); }
.hero .role { font-size: 1.05rem; color: var(--ink-soft); margin: 0; }
.hero .role a { font-weight: 500; }
.hero .tags { margin: 1rem 0 0; display:flex; flex-wrap:wrap; gap:.4rem; }
.tag { font-size: .8rem; background: var(--accent-soft); color: var(--accent);
  border: 1px solid #dde6ee; padding: .25rem .65rem; border-radius: 999px; }
.hero-actions { margin-top: 1.4rem; display:flex; flex-wrap:wrap; gap:.6rem; }
.btn { display:inline-block; padding:.5rem .95rem; border-radius: 9px;
  font-size:.9rem; font-weight:600; border:1px solid transparent; }
.btn-primary { background: var(--accent); color:#fff; }
.btn-primary:hover { background: var(--link-hover); color:#fff; text-decoration:none; }
.btn-ghost { background: var(--surface); color: var(--accent); border-color: var(--line); }
.btn-ghost:hover { background: var(--accent-soft); text-decoration:none; }

.portrait img {
  width: 190px; height: 190px; object-fit: cover; border-radius: 50%;
  box-shadow: var(--shadow); border: 4px solid #fff;
}

h2.section-title {
  font-family: var(--serif); font-size: 1.55rem; color: var(--accent);
  margin: 2.75rem 0 1.1rem; padding-bottom: .4rem;
  border-bottom: 2px solid var(--line); position: relative;
}
h2.section-title::after {
  content:""; position:absolute; left:0; bottom:-2px; width:54px; height:2px;
  background: var(--accent-2);
}
h3.sub-title { font-family: var(--serif); font-size: 1.15rem; color: var(--ink);
  margin: 1.8rem 0 .6rem; }

.lead { font-size: 1.06rem; color: var(--ink-soft); }

/* ---------- Cards / news ---------- */
.card {
  background: var(--surface); border: 1px solid var(--line);
  border-radius: var(--radius); box-shadow: var(--shadow);
  padding: 1.25rem 1.4rem; margin-bottom: 1rem;
}
.news-item { display:flex; gap:1rem; }
.news-item .date {
  flex: 0 0 auto; font-variant-numeric: tabular-nums; font-size:.82rem;
  color:#fff; background: var(--accent-2); border-radius: 7px;
  padding:.2rem .55rem; height:fit-content; white-space:nowrap; font-weight:600;
}
.news-item .body { margin:0; }
.news-item .body ul { margin:.4rem 0 0; padding-left:1.1rem; }

/* ---------- Profile / detail blocks ---------- */
.detail-grid { display:grid; grid-template-columns: 180px 1fr; gap:.4rem 1.5rem; }
.detail-grid dt { font-weight:600; color:var(--accent); }
.detail-grid dd { margin:0; color:var(--ink-soft); }
.stack { display:flex; flex-direction:column; gap:1.5rem; }

.info-card { background:var(--surface); border:1px solid var(--line);
  border-radius: var(--radius); padding:1.25rem 1.5rem; box-shadow:var(--shadow); }
.info-card h3 { margin-top:0; font-family:var(--serif); color:var(--accent); font-size:1.15rem; }
.info-card p { margin:.3rem 0; color:var(--ink-soft); }
.info-card .label { font-weight:600; color:var(--ink); }

/* ---------- Publication lists ---------- */
.toc { background:var(--accent-soft); border:1px solid #dde6ee; border-radius:var(--radius);
  padding:1rem 1.4rem; margin:1rem 0 2rem; }
.toc strong { display:block; font-family:var(--serif); color:var(--accent); margin-bottom:.4rem; }
.toc ul { list-style:none; margin:0; padding:0; display:flex; flex-wrap:wrap; gap:.3rem .9rem; }
.toc a { font-size:.92rem; }

.pub-list { list-style:none; margin:0; padding:0; counter-reset: pub; }
.pub-list > li {
  position: relative; padding: .85rem 0 .85rem 2.2rem;
  border-bottom: 1px solid var(--line);
}
.pub-list > li::before {
  counter-increment: pub; content: counter(pub);
  position:absolute; left:0; top:.95rem;
  font-size:.72rem; font-weight:700; color:var(--accent);
  background:var(--accent-soft); border:1px solid #dde6ee;
  width:1.6rem; height:1.6rem; border-radius:50%;
  display:flex; align-items:center; justify-content:center;
}
.pub-list .title { font-weight:600; color:var(--ink); }
.pub-list .venue { font-style: italic; color: var(--ink-soft); }
.pub-list .meta { color: var(--muted); font-size:.95rem; }
.pub-list .versions { margin:.35rem 0 0; padding-left:1rem;
  font-size:.9rem; color:var(--muted); border-left:2px solid var(--line); }
.pub-list .versions li { margin:.1rem 0; list-style:none; }
.pdf-tag, .ext-tag { font-size:.74rem; font-weight:600; padding:.05rem .45rem;
  border-radius:5px; margin-left:.35rem; white-space:nowrap; }
.pdf-tag { background:#fdecea; color:#b3261e; border:1px solid #f6d2cd; }
.pdf-tag:hover { background:#fbd9d4; text-decoration:none; }
.ext-tag { background:#e8f0fb; color:#1f5fa6; border:1px solid #cfe0f6; }
.ext-tag:hover { background:#d8e7f8; text-decoration:none; }

.plain-list { list-style:none; padding:0; margin:0; }
.plain-list > li { padding:.7rem 0; border-bottom:1px solid var(--line); color:var(--ink-soft); }

.material-grid { display:grid; grid-template-columns: repeat(auto-fill,minmax(220px,1fr)); gap:.6rem; }
.material-grid a { display:block; background:var(--surface); border:1px solid var(--line);
  border-radius:9px; padding:.6rem .85rem; font-size:.92rem; box-shadow:var(--shadow); }
.material-grid a:hover { border-color:var(--accent-2); text-decoration:none; background:var(--accent-soft); }
.material-grid .muted-cell { display:block; background:#f1efe9; border:1px dashed var(--line);
  border-radius:9px; padding:.6rem .85rem; font-size:.92rem; color:var(--muted); }

.back-top { font-size:.82rem; color:var(--muted); margin-left:.6rem; }

/* ---------- Footer ---------- */
.site-footer { border-top:1px solid var(--line); background:var(--surface); }
.site-footer .inner { max-width:var(--max); margin:0 auto; padding:1.6rem 1.25rem;
  display:flex; flex-wrap:wrap; justify-content:space-between; gap:1rem;
  font-size:.85rem; color:var(--muted); }
.site-footer a { color:var(--ink-soft); }

/* ---------- Responsive ---------- */
@media (max-width: 760px) {
  .hero { grid-template-columns: 1fr; gap:1.5rem; padding-top:2rem; }
  .portrait { order:-1; }
  .portrait img { width:140px; height:140px; }
  .detail-grid { grid-template-columns: 1fr; gap:.1rem 0; }
  .detail-grid dt