:root{
  --blue:#0058c9;
  --navy:#062b70;
  --cyan:#16a6d8;
  --green:#18a866;
  --pink:#f33470;
  --orange:#ff8a1f;
  --text:#10233f;
  --muted:#5b6b82;
  --line:#d8e7f8;
  --bg:#f5fbff;
  --radius:22px;
  --shadow:0 14px 35px rgba(0,64,140,.14);
}

*{box-sizing:border-box}
html{scroll-behavior:smooth}
body{
  margin:0;
  font-family:-apple-system,BlinkMacSystemFont,"Hiragino Sans","Noto Sans JP",Meiryo,sans-serif;
  color:var(--text);
  background:linear-gradient(180deg,#fff 0%,var(--bg) 55%,#fff 100%);
  line-height:1.75;
}
a{color:inherit;text-decoration:none}
img{max-width:100%;display:block}
.container{width:min(1180px,92vw);margin-inline:auto}

/* Header */
.site-header{
  position:sticky;
  top:0;
  z-index:10;
  display:flex;
  align-items:center;
  justify-content:space-between;
  gap:24px;
  padding:14px min(4vw,48px);
  background:rgba(255,255,255,.92);
  backdrop-filter:blur(14px);
  box-shadow:0 2px 18px rgba(0,45,110,.08);
}
.logo{display:flex;align-items:center;gap:12px;color:var(--navy);font-weight:700;line-height:1.25}
.mark{display:grid;place-items:center;width:44px;height:44px}
.nav{display:flex;align-items:center;gap:20px;font-weight:700;font-size:14px}
.btn{display:inline-flex;align-items:center;justify-content:center;border-radius:999px;padding:.8em 1.35em;color:#fff;font-weight:800;box-shadow:var(--shadow)}
.btn-blue{background:var(--blue)}
.btn-pink{background:var(--pink)}
.btn-green{background:var(--green)}
#nav-toggle{display:none}
.hamburger{display:none}

/* Hero */
.hero{
  display:grid;
  grid-template-columns:1.05fr .95fr;
  min-height:640px;
  overflow:hidden;
  background:radial-gradient(circle at 75% 20%,#dff8ff 0 22%,transparent 40%),linear-gradient(115deg,#effbff 0 52%,#fff 52%);
  border-bottom:1px solid var(--line);
}
.hero-copy{padding:70px 0 60px min(6vw,90px);max-width:700px}
.eyebrow{color:var(--navy);font-size:clamp(20px,2vw,32px);font-weight:900;letter-spacing:.08em}
.hero h1{font-size:clamp(56px,7vw,108px);line-height:1.05;margin:.15em 0;color:var(--navy);letter-spacing:.04em}
.hero h1 span{color:#0aa1c6}
.lead{font-size:clamp(16px,1.4vw,20px);font-weight:700;max-width:590px}
.event-meta{display:grid;gap:9px;margin-top:28px;font-size:18px}
.event-meta b{font-size:1.35em}

.hero-visual{
  position:relative;
  min-height:600px;
  padding:64px 54px;
}

/* Pamphlet images */
.pamphlet-pair{
  display:grid;
  grid-template-columns:repeat(2,minmax(0,1fr));
  gap:18px;
  align-items:start;
}
.pamphlet-pair img{
  width:100%;
  border-radius:24px;
  border:8px solid #fff;
  box-shadow:var(--shadow);
  background:#fff;
}

/* Three square research images */
.hero-square-gallery{
  display:grid;
  grid-template-columns:repeat(3,minmax(0,1fr));
  gap:14px;
  margin-top:18px;
}
.hero-square-gallery img{
  width:100%;
  aspect-ratio:1 / 1;
  object-fit:cover;
  border-radius:22px;
  border:6px solid #fff;
  box-shadow:0 10px 24px rgba(0,64,140,.12);
  background:linear-gradient(135deg,#e9f7ff,#fff 52%,#bfeaff);
}
.bubble{
  position:absolute;
  top:64px;
  left:20px;
  width:170px;
  height:170px;
  border-radius:50%;
  background:var(--navy);
  color:#fff;
  border:6px solid #fff;
  display:grid;
  place-items:center;
  text-align:center;
  font-weight:900;
  transform:rotate(-4deg);
  box-shadow:var(--shadow);
}

/* Sections */
h2{font-size:clamp(26px,3vw,40px);color:var(--blue);margin:0 0 22px}
.features,.program,.themes,.split{padding:56px 0}
.grid{display:grid;gap:18px}
.four{grid-template-columns:repeat(4,1fr)}
.five{grid-template-columns:repeat(5,1fr)}
.grid article,.timeline article,.cta-card{background:#fff;border:1px solid var(--line);border-radius:var(--radius);padding:24px;box-shadow:var(--shadow)}
.grid b{display:block;color:var(--blue);font-size:20px}
.grid p{color:var(--muted);margin:.4em 0 0}
.timeline{display:grid;grid-template-columns:repeat(3,1fr);gap:20px}
.timeline article{border-top:14px solid}
.timeline .blue{border-color:var(--blue)}
.timeline .green{border-color:var(--green)}
.timeline .pink{border-color:var(--pink)}
time{font-size:24px;font-weight:900}
.timeline h3{font-size:23px;margin:.2em 0;color:var(--navy)}
.circle{display:block;width:96px;aspect-ratio:1;margin:0 auto 14px;border-radius:50%;background:radial-gradient(circle,#fff 0 8%,#149ee7 9% 14%,#08489b 45%,#19bfd6 100%)}
.c2{background:radial-gradient(circle,#eefcff 0 8%,#4fd4ff 9% 24%,#0058c9 60%,#061c55 100%)}
.c3{background:radial-gradient(circle,#50f08b,#064c35 55%,#001d17)}
.c4{background:radial-gradient(circle,#ffdc52,#ff5a22 55%,#750808)}
.c5{background:radial-gradient(circle,#fff 0 8%,#b688ff 9% 24%,#5937d8 60%,#1b0f55 100%)}
.themes article{text-align:center}
.split{display:grid;grid-template-columns:1.25fr .75fr;gap:22px}
.cta-card{padding:32px}
.cta-card h2{margin-bottom:8px}
.cta-card ul{padding-left:1.2em}
.student{background:linear-gradient(135deg,#fff,#f1f8ff)}
.visitor{background:linear-gradient(135deg,#fff,#effff8)}
.visitor-notice{margin-top:22px;background:linear-gradient(135deg,#fff7fb,#eef8ff);border:2px solid var(--text);border-radius:var(--radius);padding:28px 32px;box-shadow:var(--shadow);text-align:center}
.visitor-notice p{margin:0;color:var(--navy);font-size:clamp(22px,2.6vw,34px);font-weight:900;line-height:1.5}
.footer{margin-top:40px;padding:30px 5vw;color:#fff;background:var(--navy);display:flex;justify-content:space-between;gap:20px;flex-wrap:wrap}
.footer p{margin:0}

/* Tablet */
@media (max-width:980px){
  .hamburger{display:grid;gap:5px;cursor:pointer}
  .hamburger span{display:block;width:30px;height:3px;background:var(--navy);border-radius:9px}
  .nav{position:absolute;inset:72px 18px auto 18px;display:none;flex-direction:column;align-items:stretch;background:#fff;border:1px solid var(--line);border-radius:18px;padding:20px;box-shadow:var(--shadow)}
  #nav-toggle:checked~.nav{display:flex}
  .nav .btn{width:100%}

  .hero{grid-template-columns:1fr}
  .hero-copy{padding:52px 5vw 20px}
  .hero-visual{min-height:420px;padding:24px 5vw 48px}

  .pamphlet-pair{grid-template-columns:1fr;gap:24px}
  .pamphlet-pair img{max-width:560px;margin-inline:auto}
  .hero-square-gallery{grid-template-columns:repeat(2,minmax(0,1fr));gap:18px;max-width:720px;margin:24px auto 0}

  .bubble{right:6vw;left:auto;top:12px;width:140px;height:140px}
  .four,.five,.timeline,.split{grid-template-columns:1fr 1fr}
  .visitor-notice{grid-column:1/-1;padding:24px}
}

/* Smartphone */
@media (max-width:620px){
  .site-header{padding:12px 18px}
  .logo{font-size:13px}
  .mark{width:38px;height:38px}
  .hero h1{font-size:48px}
  .lead,.event-meta{font-size:15px}
  .hero-visual{padding-inline:5vw}

  .pamphlet-pair{grid-template-columns:1fr;gap:22px}
  .pamphlet-pair img{border-width:6px;border-radius:18px}
  .hero-square-gallery{grid-template-columns:1fr;gap:20px;max-width:420px}
  .hero-square-gallery img{border-radius:18px;border-width:5px}

  .four,.five,.timeline,.split{grid-template-columns:1fr}
  .features,.program,.themes,.split{padding:38px 0}
  .grid article,.timeline article,.cta-card{padding:20px}
  .footer{font-size:13px}
  .bubble{position:static;width:auto;height:auto;border-radius:18px;padding:16px;margin-top:20px;transform:none}
  .visitor-notice{margin-top:18px;padding:22px 18px;border-radius:18px;text-align:left}
  .visitor-notice p{font-size:22px;line-height:1.55}
}