:root{
    --bg:#FFFFFF;
    --bg-alt:#E8F2FB;
    --ink:#283A54;
    --ink-soft:#586B82;
    --blue:#A9D4EF;
    --blue-deep:#2A6FA8;
    --blue-pale:#E1F0FB;
    --panel-deep:#3568A8;
    --border:#D7E9F6;
    --max: 1120px;
    box-sizing:border-box;
    padding-top: env(safe-area-inset-top, 0px);
    padding-bottom: env(safe-area-inset-bottom, 0px);
  }
  @media (prefers-color-scheme: dark){
    :root:not([data-theme="light"]){
      --bg:#FFFFFF; --bg-alt:#E8F2FB; --ink:#283A54; --ink-soft:#586B82;
      --blue:#A9D4EF; --blue-deep:#2A6FA8; --blue-pale:#E1F0FB;
      --panel-deep:#3568A8; --border:#D7E9F6;
    }
  }
  :root[data-theme="dark"]{
    --bg:#FFFFFF; --bg-alt:#E8F2FB; --ink:#283A54; --ink-soft:#586B82;
    --blue:#A9D4EF; --blue-deep:#2A6FA8; --blue-pale:#E1F0FB;
    --panel-deep:#3568A8; --border:#D7E9F6;
  }
  *{box-sizing:inherit;}
  html{scroll-behavior:smooth; scroll-padding-top: calc(112px + env(safe-area-inset-top,0px));}
  body{
    margin:0; background:var(--bg); color:var(--ink);
    font-family:'Noto Sans JP','Hiragino Sans','Yu Gothic',sans-serif;
    font-size:16px; line-height:1.85; -webkit-font-smoothing:antialiased;
  }
  h1,h2,h3,.stat-num{
    font-family:'Zen Kaku Gothic New','Hiragino Kaku Gothic ProN','Yu Gothic',sans-serif;
  }
  a{color:var(--blue-deep);}
  img,svg{max-width:100%;}
  .wrap{max-width:var(--max); margin:0 auto; padding:0 24px;}
  .prose{max-width:680px;}

  /* Nav */
  header.site{
    position:sticky; top: env(safe-area-inset-top,0px); z-index:20;
    background:color-mix(in srgb, var(--bg) 88%, transparent);
    backdrop-filter: blur(8px);
    border-bottom:1px solid var(--border);
  }
  header.site .wrap{display:flex; align-items:center; justify-content:space-between; padding:14px 0; gap:16px; flex-wrap:wrap;}
  .brand{display:flex; align-items:center; text-decoration:none;}
  .brand img{height:68px; width:auto; display:block;}
  nav.primary{display:flex; gap:22px; overflow-x:auto; scrollbar-width:none;}
  nav.primary::-webkit-scrollbar{display:none;}
  nav.primary a{
    color:var(--ink-soft); text-decoration:none; font-size:14px; font-weight:500;
    white-space:nowrap; padding:4px 2px; border-bottom:2px solid transparent;
  }
  nav.primary a:hover, nav.primary a:focus-visible{ color:var(--ink); border-color:var(--blue); }
  .lang-link{
    border:1px solid var(--border) !important; border-radius:100px; padding:5px 14px !important;
    color:var(--blue-deep) !important; font-weight:600 !important; margin-left:6px;
  }
  .lang-link:hover, .lang-link:focus-visible{ border-color:var(--blue) !important; }

  /* Hero */
  .hero{position:relative; overflow:hidden; background:linear-gradient(170deg, var(--blue-pale) 0%, var(--bg) 62%);}
  .hero .wrap{position:relative; padding:88px 24px 64px; z-index:2;}
  .hero svg.streamlines{position:absolute; inset:0; width:100%; height:100%; opacity:.9; z-index:1;}
  .eyebrow-tag{
    display:inline-block; font-size:13px; color:var(--blue-deep); border:1px solid var(--blue);
    padding:5px 12px; border-radius:100px; margin-bottom:22px; background:var(--bg);
  }
  .hero h1{
    font-size:clamp(30px, 5.4vw, 52px); font-weight:900; line-height:1.35; margin:0 0 6px; color:var(--ink);
  }
  .hero .sub{ font-size:clamp(16px,2.4vw,20px); color:var(--blue-deep); margin:0 0 26px; font-weight:500;}
  .hero p.desc{max-width:640px; color:var(--ink-soft); font-size:16px; line-height:1.9; margin:0 0 8px;}
  .hero .meta{color:var(--ink-soft); font-size:14px; margin-top:18px;}
  @media (prefers-reduced-motion: no-preference){
    .hero .wrap > *{ animation: rise .7s ease both; }
    .hero .sub{ animation-delay:.08s; }
    .hero p.desc{ animation-delay:.16s; }
    .hero .meta{ animation-delay:.24s; }
    @keyframes rise{ from{opacity:0; transform:translateY(10px);} to{opacity:1; transform:translateY(0);} }
  }

  /* Sections */
  section{ padding:76px 0; }
  section.alt{ background:var(--bg-alt); }
  .section-head{ margin-bottom:34px; }
  .section-head .kicker{ color:var(--blue-deep); font-weight:600; font-size:14px; margin:0 0 8px; }
  h2{ font-size:clamp(22px,3vw,28px); margin:0; line-height:1.4; }
  h2 + p.lead{ color:var(--ink-soft); margin-top:10px; max-width:640px; }

  .stack{ display:flex; flex-direction:column; gap:26px; }
  .stack .block h3{ font-size:16px; margin:0 0 8px; color:var(--blue-deep); }
  .stack .block p{ margin:0; color:var(--ink); max-width:700px; }

  /* Subtheme cards */
  .core-grid{ display:grid; grid-template-columns:repeat(auto-fit,minmax(260px,1fr)); gap:1px; background:var(--border); border:1px solid var(--border); }
  .core{ background:var(--bg); padding:26px 24px; border-left:3px solid var(--blue); }
  section.alt .core{ background:var(--bg-alt); }
  .core.core-wide{ grid-column:1 / -1; background:var(--blue-pale); border-left:3px solid var(--blue-deep); }
  .core .code{ font-weight:700; color:var(--blue-deep); font-size:14px; margin-bottom:6px; }
  .core h3{ margin:0 0 10px; font-size:17px; line-height:1.5; }
  .core p{ margin:0; color:var(--ink-soft); font-size:14.5px; line-height:1.8; }

  /* Team */
  .team-pi{
    display:flex; gap:18px; align-items:flex-start; padding:22px 24px; background:var(--bg-alt);
    border:1px solid var(--border); margin-bottom:34px;
  }
  .team-pi .role{ font-size:13px; color:var(--blue-deep); font-weight:600; }
  .team-pi .name{ font-size:19px; font-weight:700; margin:4px 0 2px; }
  .team-pi .aff{ font-size:14px; color:var(--ink-soft); }
  .org-cols{ display:grid; grid-template-columns:1fr 1fr; gap:40px; }
  @media (max-width:700px){ .org-cols{grid-template-columns:1fr; gap:28px;} }
  .org-cols h3{ font-size:14px; color:var(--ink-soft); font-weight:600; margin:0 0 14px; border-bottom:1px solid var(--border); padding-bottom:10px;}
  .org-list{ list-style:none; margin:0; padding:0; display:flex; flex-direction:column; gap:12px; }
  .org-list li{ font-size:15px; line-height:1.6; }
  .org-list .inst{ font-weight:600; }
  .org-list .person{ color:var(--ink-soft); font-size:13.5px; }
  .group-heading{ font-size:17px; font-weight:700; color:var(--ink); margin:34px 0 16px; padding-bottom:8px; border-bottom:1px solid var(--border); }
  .group-heading:first-of-type{ margin-top:4px; }
  .inst-block{ margin-bottom:26px; }
  .inst-block .inst-name{
    font-weight:700; font-size:14.5px; margin:0 0 12px; color:var(--blue-deep);
    padding-bottom:8px; border-bottom:1px solid var(--border);
  }
  .member-list{ list-style:none; margin:0; padding:0; display:flex; flex-wrap:wrap; gap:6px 10px; }
  .member-list li{ font-size:14.5px; line-height:1.6; }
  .member-list li:not(:last-child)::after{ content:"、"; color:var(--ink-soft); }
  html[lang="en"] .member-list li:not(:last-child)::after{ content:","; }
  .member-list .mname{ font-weight:400; color:var(--ink); }
  .team-note{ margin-top:28px; font-size:13.5px; color:var(--ink-soft); }

  /* Empty state (results) */
  .empty{
    border:1px dashed var(--border); padding:40px 28px; text-align:left; color:var(--ink-soft);
    max-width:640px;
  }
  .empty strong{ display:block; color:var(--ink); font-size:16px; margin-bottom:8px; }

  /* Recruit */
  .recruit-box{
    background:var(--blue-pale); color:var(--ink); padding:40px 32px; display:flex; flex-wrap:wrap;
    gap:28px; align-items:center; justify-content:space-between; border:1px solid var(--border);
  }
  .recruit-box .txt{ max-width:600px; }
  .recruit-box h3{ margin:0 0 10px; font-size:19px; color:var(--ink); }
  .recruit-box p{ margin:0; color:var(--ink-soft); font-size:14.5px; line-height:1.8; }
  .btn{
    display:inline-block; background:var(--blue-deep); color:#FFFFFF; font-weight:700;
    font-size:14.5px; padding:13px 26px; text-decoration:none; white-space:nowrap;
    border:1px solid var(--blue-deep);
  }
  .btn:hover, .btn:focus-visible{ background:#255E93; border-color:#255E93; }

  /* Contact / footer */
  .contact-line{ font-size:16px; }
  .contact-line a{ font-weight:600; }
  footer{ border-top:1px solid var(--border); padding:34px 0; }
  footer .wrap{ display:flex; flex-wrap:wrap; gap:18px 24px; justify-content:space-between; align-items:center; color:var(--ink-soft); font-size:13px; }
  footer .foot-brand{ display:flex; align-items:center; gap:10px; }
  footer .foot-brand img{ height:56px; width:auto; }
  footer .foot-text{ display:flex; flex-direction:column; gap:4px; }

  :focus-visible{ outline:2px solid var(--blue-deep); outline-offset:2px; }
  .skip-link{
    position:absolute; left:-9999px; top:0; z-index:50;
    background:var(--blue-deep); color:#FFFFFF; padding:10px 18px; text-decoration:none; font-size:14px;
  }
  .skip-link:focus{ left:12px; top:12px; }