:root{
  /* ===== Dark base ===== */
  --bg-main:#111827;
  --bg-sub:#0f172a;

  /* Text on dark */
  --text:#f9fafb;
  --sub:#e5e7eb;
  --muted:#cbd5f5;

  /* Accent */
  --accent:#60a5fa;
  --border:rgba(148,163,184,0.28);

  /* ===== Light surfaces ===== */
  --light-bg:rgba(255,255,255,0.94);
  --light-card:#ffffff;
  --light-text:#0f172a;
  --light-sub:#334155;
  --light-muted:#475569;
  --light-border:#e5e7eb;

  --radius:18px;
  --max:1040px;
}

*{box-sizing:border-box;}
html,body{margin:0;padding:0;}

body{
  font-family:system-ui,-apple-system,"Segoe UI",Roboto,
  "Noto Sans JP","Hiragino Kaku Gothic ProN","Yu Gothic",sans-serif;
  color:var(--text);
  line-height:1.75;
  background:
    radial-gradient(900px 520px at 15% 10%, rgba(96,165,250,.15), transparent 60%),
    radial-gradient(900px 520px at 85% 20%, rgba(56,189,248,.12), transparent 58%),
    linear-gradient(180deg,var(--bg-sub),var(--bg-main));
}

a{color:inherit;text-decoration:none;}

.container{
  max-width:var(--max);
  margin:0 auto;
  padding:0 20px;
}

/* =========================================================
   Header
   ========================================================= */
header{
  position:sticky;
  top:0;
  z-index:10;
  background:rgba(255,255,255,.94);
  border-bottom:1px solid rgba(203,213,225,.65);
}

.nav{
  display:flex;
  align-items:flex-end;
  justify-content:space-between;
  padding:14px 0;
  gap:24px;
}

.brand{
  display:flex;
  align-items:center;
  gap:16px;
}

.brand .logo{
  width:90px;
  height:90px;
  object-fit:contain;
  flex-shrink:0;
}

.brand-text{
  display:flex;
  flex-direction:column;
}

.lab-jp{
  font-size:20px;
  font-weight:800;
  letter-spacing:.02em;
  color:var(--light-text);
}

.lab-en{
  font-size:14px;
  font-weight:600;
  color:var(--light-sub);
  margin-top:2px;
}

.affiliation{
  margin-top:4px;
  font-size:12px;
  color:var(--light-muted);
  line-height:1.4;
}
.affiliation span{display:block;}

.navlinks{
  display:flex;
  gap:16px;
  white-space:nowrap;
  font-size:16px;
}

.navlinks a{
  padding:6px 10px;
  border-radius:999px;
  color:var(--light-sub);
}
.navlinks a:hover{
  background:#e8f0ff;
  color:#1d4ed8;
}

/* =========================================================
   Main
   ========================================================= */
main{padding:30px 0 60px;}

/* =========================================================
   Hero (Light)
   ========================================================= */
.hero{
  margin-top:20px;
  background:var(--light-bg);
  border:1px solid var(--light-border);
  border-radius:var(--radius);
  padding:36px;
  color:var(--light-text);
}

.hero h1{
  margin:0 0 10px;
  font-size:28px;
  font-weight:700;
  line-height:1.25;
}

.hero-text{
  margin:0;
  color:var(--light-sub);
}

/* ===== Hero badges layout ===== */
.hero-badges{
  display:flex;
  gap:8px;
  flex-wrap:wrap;
}

.hero-badges-main{margin:8px 0 12px;}
.hero-badges-sub{margin-top:14px;}

/* =========================================================
   BADGE (復旧・正式版)
   ========================================================= */
.badge{
  display:inline-flex;
  align-items:baseline;
  gap:6px;

  padding:4px 10px;
  border-radius:12px;
  border:1px solid rgba(15,23,42,0.12);
  background:rgba(2,6,23,0.04);

  line-height:1.2;
}

.badge-en{
  font-size:12px;
  font-weight:600;
  color:var(--light-text);
  white-space:nowrap;
}

.badge-jp{
  font-size:11px;
  color:var(--light-muted);
  white-space:nowrap;
}
.badge-jp::before{
  content:"•";
  margin-right:6px;
  color:rgba(100,116,139,.9);
}

/* 強弱 */
.hero-badges-main .badge{
  background:rgba(96,165,250,.10);
  border-color:rgba(37,99,235,.18);
}
.hero-badges-sub .badge{
  background:rgba(2,6,23,.02);
  border-color:rgba(15,23,42,.10);
}

/* =========================================================
   Section title (Dark)
   ========================================================= */
.section-title{
  margin:42px 0 12px;
  font-size:18px;
  display:flex;
  align-items:center;
  gap:10px;
  color:var(--text);
}
.section-title::before{
  content:"";
  width:10px;
  height:10px;
  border-radius:999px;
  background:var(--accent);
}

/* =========================================================
   Grid / Card (Light)
   ========================================================= */
.grid{
  display:grid;
  grid-template-columns:repeat(auto-fit,minmax(270px,1fr));
  gap:16px;
  margin-top:28px;
  padding:28px;
  background:var(--light-bg);
  border-radius:20px;
  border:1px solid var(--light-border);
}

.card{
  background:var(--light-card);
  border:1px solid var(--light-border);
  border-radius:16px;
  padding:20px;
  color:var(--light-text);
}

.card h2{
  margin:0 0 4px;
  font-size:18px;
}

.card p,
.card li{
  color:var(--light-sub);
}

.role{
  margin:4px 0 8px;
  font-weight:600;
  color:var(--light-sub);
}

/* =========================================================
   Lists
   ========================================================= */
/* Dark background */
.list{
  padding-left:18px;
}
.list li{
  margin:6px 0;
  color:var(--sub);
}

/* Light background override */
.hero .list li,
.grid .list li,
.card .list li{
  color:var(--light-sub);
}

/* =========================================================
   Footer
   ========================================================= */
.footer{
  margin-top:56px;
  padding:22px 0;
  font-size:12px;
  color:var(--muted);
  text-align:center;
  border-top:1px solid var(--border);
  background:rgba(15,23,42,.6);
}

/* =========================================================
   Mobile
   ========================================================= */
@media(max-width:720px){
  .brand .logo{width:64px;height:64px;}
  .nav{align-items:flex-start;}
  .navlinks{font-size:14px;gap:10px;}
  .hero{padding:24px;}
  .hero h1{font-size:26px;}
  .grid{padding:18px;}
}

/* =========================================================
   Mobile hamburger menu
   ========================================================= */
.menu-toggle{
  display:none;
  width:42px;
  height:42px;
  border-radius:12px;
  border:1px solid var(--light-border);
  background:#fff;
  cursor:pointer;
  position:relative;
  padding:0;
}

.menu-toggle span{
  position:absolute;
  left:11px;
  right:11px;
  height:2px;
  background:var(--light-sub);
  border-radius:999px;
  transition: transform .15s ease, opacity .15s ease, top .15s ease;
}
.menu-toggle span:nth-child(1){ top:14px; }
.menu-toggle span:nth-child(2){ top:20px; }
.menu-toggle span:nth-child(3){ top:26px; }

/* open state (X icon) */
.menu-toggle.is-open span:nth-child(1){ top:20px; transform:rotate(45deg); }
.menu-toggle.is-open span:nth-child(2){ opacity:0; }
.menu-toggle.is-open span:nth-child(3){ top:20px; transform:rotate(-45deg); }

@media (max-width: 720px){
  .nav{
    align-items:flex-start;
    gap:14px;
  }

  /* show hamburger */
  .menu-toggle{
    display:inline-block;
    margin-left:auto;
    margin-right:12px;
  }

  /* dropdown nav */
  .navlinks{
    display:none;              /* hidden by default on mobile */
    position:absolute;
    right:20px;
    top:92px;                  /* ヘッダー内で落ちる位置（必要なら微調整） */
    flex-direction:column;
    gap:8px;

    padding:12px;
    background:rgba(255,255,255,0.98);
    border:1px solid var(--light-border);
    border-radius:16px;
    box-shadow:0 10px 30px rgba(15,23,42,0.12);
    white-space:normal;
    min-width:220px;
    z-index:20;
  }

  .nav{ position:relative; }   /* dropdown の基準 */

  .navlinks a{
    display:block;
    padding:10px 12px;
    border-radius:12px;
  }

  /* open */
  .navlinks.is-open{
    display:flex;
  }
}