/* ===== リセット & ベース ===== */
*, *::before, *::after {
  box-sizing: border-box;
  margin: 0;
  padding: 0;
}

:root {
  --primary:   #1a237e;   /* ネイビー */
  --accent:    #3949ab;
  --accent-lt: #5c6bc0;
  --bg:        #ffffff;
  --bg-gray:   #f5f6fa;
  --text:      #212121;
  --text-sub:  #555;
  --border:    #e0e0e0;
  --radius:    10px;
  --shadow:    0 2px 12px rgba(0,0,0,0.09);
  --max-w:     1000px;
  --nav-h:     60px;
}

html {
  scroll-behavior: smooth;
}

body {
  font-family: "Hiragino Kaku Gothic ProN", "Noto Sans JP", "Yu Gothic", sans-serif;
  color: var(--text);
  background: var(--bg);
  line-height: 1.7;
}

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

ul { list-style: none; }

/* ===== ナビゲーション ===== */
#site-header {
  position: sticky;
  top: 0;
  z-index: 100;
  background: var(--primary);
  color: #fff;
  box-shadow: 0 2px 8px rgba(0,0,0,0.3);
}

.nav-inner {
  max-width: var(--max-w);
  margin: 0 auto;
  padding: 0 1.5rem;
  height: var(--nav-h);
  display: flex;
  align-items: center;
  gap: 2rem;
}

.nav-logo {
  font-size: 1.3rem;
  font-weight: 700;
  letter-spacing: .05em;
  flex: 1;
  color: #fff;
  text-decoration: none;
}

.nav-inner nav {
  display: flex;
  gap: 1.8rem;
}

.nav-inner nav a {
  color: rgba(255,255,255,0.85);
  font-size: 0.9rem;
  font-weight: 500;
  letter-spacing: .03em;
  transition: color .2s;
}
.nav-inner nav a:hover,
.nav-inner nav a.nav-current {
  color: #fff;
  text-decoration: none;
}


.menu-toggle {
  display: none;
  background: none;
  border: none;
  color: #fff;
  font-size: 1.5rem;
  cursor: pointer;
  margin-left: auto;
}

.mobile-menu {
  display: none;
  flex-direction: column;
  background: var(--primary);
  padding: .5rem 1.5rem 1rem;
}
.mobile-menu a {
  color: rgba(255,255,255,0.85);
  padding: .5rem 0;
  border-bottom: 1px solid rgba(255,255,255,0.1);
  font-size: 0.95rem;
}
.mobile-menu.open { display: flex; }

/* ===== ヒーロー ===== */
.hero {
  background: linear-gradient(135deg, var(--primary) 0%, var(--accent) 60%, var(--accent-lt) 100%);
  color: #fff;
  padding: 5rem 1.5rem 4rem;
  text-align: center;
}

.hero-inner {
  max-width: 700px;
  margin: 0 auto;
}

.hero-label {
  font-size: 0.9rem;
  opacity: 0.8;
  margin-bottom: 0.5rem;
  letter-spacing: .05em;
}

.hero h1 {
  font-size: clamp(1.8rem, 5vw, 2.8rem);
  font-weight: 700;
  margin-bottom: .8rem;
  letter-spacing: .03em;
}

.hero-sub {
  font-size: 1rem;
  opacity: 0.85;
  margin-bottom: 2rem;
}

.hero-links {
  display: flex;
  gap: 1rem;
  justify-content: center;
  flex-wrap: wrap;
}

.btn {
  display: inline-block;
  padding: .55rem 1.3rem;
  border-radius: 50px;
  font-size: 0.88rem;
  font-weight: 600;
  transition: background .2s, color .2s;
  cursor: pointer;
  text-decoration: none;
}

.btn-outline {
  border: 2px solid rgba(255,255,255,0.7);
  color: #fff;
  background: transparent;
}
.btn-outline:hover {
  background: rgba(255,255,255,0.15);
  text-decoration: none;
}

/* ===== セクション共通 ===== */
.section {
  padding: 5rem 1.5rem;
}
.section-gray { background: var(--bg-gray); }

.container {
  max-width: var(--max-w);
  margin: 0 auto;
}

.section-title {
  font-size: 1.7rem;
  font-weight: 700;
  color: var(--primary);
  margin-bottom: 2.5rem;
  padding-bottom: .6rem;
  border-bottom: 3px solid var(--accent-lt);
  display: inline-block;
}

.section-lead {
  margin-top: -1.5rem;
  margin-bottom: 2.5rem;
  color: var(--text-sub);
}

/* ===== About ===== */
.about-grid {
  display: grid;
  grid-template-columns: 200px 1fr;
  gap: 3rem;
  align-items: start;
}

.photo-placeholder {
  width: 180px;
  height: 220px;
  background: var(--bg-gray);
  border: 2px dashed var(--border);
  border-radius: var(--radius);
  display: flex;
  align-items: center;
  justify-content: center;
  color: #aaa;
  font-size: 0.9rem;
}

.about-text p {
  margin-bottom: 1rem;
  color: var(--text-sub);
}

.about-meta {
  margin-top: 1.5rem;
  display: flex;
  flex-direction: column;
  gap: .6rem;
}
.about-meta > div {
  display: flex;
  gap: 1rem;
  font-size: 0.9rem;
}
.about-meta strong {
  color: var(--primary);
  min-width: 4em;
}
.about-meta span { color: var(--text-sub); }

/* ===== Research カード ===== */
.card-grid {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(270px, 1fr));
  gap: 1.5rem;
}

.card {
  background: var(--bg);
  border-radius: var(--radius);
  padding: 1.8rem 1.6rem;
  box-shadow: var(--shadow);
  border: 1px solid var(--border);
  transition: transform .2s, box-shadow .2s;
}
.card:hover {
  transform: translateY(-4px);
  box-shadow: 0 6px 24px rgba(0,0,0,0.12);
}

.card-icon {
  font-size: 2rem;
  margin-bottom: .8rem;
}

.card h3 {
  font-size: 1.05rem;
  font-weight: 700;
  color: var(--primary);
  margin-bottom: .6rem;
}

.card p {
  font-size: 0.9rem;
  color: var(--text-sub);
  margin-bottom: 1rem;
}

.card-tags {
  display: flex;
  gap: .5rem;
  flex-wrap: wrap;
}

.tag {
  background: #e8eaf6;
  color: var(--accent);
  font-size: 0.75rem;
  font-weight: 600;
  padding: .2rem .7rem;
  border-radius: 50px;
}

/* ===== Publications ===== */
.pub-filter {
  display: flex;
  gap: .6rem;
  margin-bottom: 2rem;
  flex-wrap: wrap;
}

.filter-btn {
  background: var(--bg-gray);
  border: 1px solid var(--border);
  color: var(--text-sub);
  padding: .4rem 1.1rem;
  border-radius: 50px;
  font-size: 0.85rem;
  cursor: pointer;
  transition: background .2s, color .2s;
}
.filter-btn.active,
.filter-btn:hover {
  background: var(--accent);
  color: #fff;
  border-color: var(--accent);
}

.pub-list {
  display: flex;
  flex-direction: column;
  gap: 1.2rem;
}

.pub-item {
  display: flex;
  gap: 1rem;
  background: var(--bg);
  border: 1px solid var(--border);
  border-radius: var(--radius);
  padding: 1.2rem 1.4rem;
  box-shadow: var(--shadow);
  align-items: flex-start;
  transition: opacity .2s;
}
.pub-item.hidden { display: none; }

.pub-badge {
  font-size: 0.7rem;
  font-weight: 700;
  padding: .25rem .6rem;
  border-radius: 4px;
  white-space: nowrap;
  margin-top: .2rem;
  flex-shrink: 0;
}
.pub-badge.journal    { background: #e3f2fd; color: #1565c0; }
.pub-badge.conference { background: #f3e5f5; color: #7b1fa2; }

.pub-content { flex: 1; }

.pub-title {
  font-weight: 600;
  font-size: 0.95rem;
  margin-bottom: .25rem;
  color: var(--text);
}

.pub-authors {
  font-size: 0.85rem;
  color: var(--text-sub);
  margin-bottom: .2rem;
}

.pub-venue {
  font-size: 0.82rem;
  color: #888;
  font-style: italic;
  margin-bottom: .5rem;
}

.pub-links { display: flex; gap: .6rem; }
.pub-link {
  font-size: 0.8rem;
  font-weight: 600;
  color: var(--accent);
}

/* ===== Access ===== */
.access-grid {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: 3rem;
  align-items: start;
}

.access-block {
  margin-bottom: 1.8rem;
}
.access-block h3 {
  font-size: 0.95rem;
  font-weight: 700;
  color: var(--primary);
  margin-bottom: .6rem;
  text-transform: uppercase;
  letter-spacing: .05em;
}
.access-block p,
.access-block li {
  font-size: 0.9rem;
  color: var(--text-sub);
  line-height: 1.8;
}
.access-block ul li::before {
  content: "▸ ";
  color: var(--accent-lt);
}

.map-placeholder {
  width: 100%;
  height: 320px;
  background: var(--bg-gray);
  border: 2px dashed var(--border);
  border-radius: var(--radius);
  display: flex;
  flex-direction: column;
  align-items: center;
  justify-content: center;
  color: #aaa;
  text-align: center;
  padding: 1rem;
}

.access-map-image {
  display: block;
  width: 100%;
  height: auto;
  border: 1px solid var(--border);
  border-radius: var(--radius);
  box-shadow: var(--shadow);
}

/* ===== フッター ===== */
.site-footer {
  background: var(--primary);
  color: rgba(255,255,255,0.7);
  text-align: center;
  padding: 1.5rem;
  font-size: 0.85rem;
}

/* ===== レスポンシブ ===== */
@media (max-width: 700px) {
  .nav-inner nav { display: none; }
  .menu-toggle { display: block; }

  .about-grid {
    grid-template-columns: 1fr;
  }
  .about-photo {
    display: flex;
    justify-content: center;
  }

  .access-grid {
    grid-template-columns: 1fr;
  }

  .section { padding: 3.5rem 1.2rem; }
  .hero    { padding: 4rem 1.2rem 3rem; }
}