:root {
  --bg: #fafaf7;
  --surface: #ffffff;
  --text: #1f2328;
  --text-muted: #57606a;
  --text-soft: #6e7781;
  --accent: #1f3a5f;
  --accent-hover: #284c7d;
  --border: #e5e7eb;
  --border-soft: #eef0f3;
  --shadow: 0 1px 2px rgba(15, 23, 42, 0.04), 0 4px 16px rgba(15, 23, 42, 0.04);
  --radius: 12px;
  --radius-sm: 8px;
  --max-width: 1080px;
  --serif: "Source Serif 4", "Source Serif Pro", "Iowan Old Style", "Apple Garamond", Georgia, "Noto Serif JP", serif;
  --sans: "Inter", -apple-system, BlinkMacSystemFont, "Segoe UI", "Hiragino Sans", "Noto Sans JP", sans-serif;
}

@media (prefers-color-scheme: dark) {
  :root {
    --bg: #0f1115;
    --surface: #161a21;
    --text: #e6edf3;
    --text-muted: #a8b1bd;
    --text-soft: #8b95a3;
    --accent: #8ab4f8;
    --accent-hover: #b3cdfa;
    --border: #2a313c;
    --border-soft: #1f242d;
    --shadow: 0 1px 2px rgba(0, 0, 0, 0.3), 0 4px 16px rgba(0, 0, 0, 0.25);
  }
}

* { box-sizing: border-box; }

html { scroll-behavior: smooth; }

body {
  margin: 0;
  background: var(--bg);
  color: var(--text);
  font-family: var(--sans);
  font-size: 16px;
  line-height: 1.65;
  -webkit-font-smoothing: antialiased;
  -moz-osx-font-smoothing: grayscale;
}

a {
  color: var(--accent);
  text-decoration: none;
  border-bottom: 1px solid transparent;
  transition: border-color 0.15s ease, color 0.15s ease;
}
a:hover { color: var(--accent-hover); border-bottom-color: var(--accent-hover); }

h1, h2, h3, h4, h5 {
  font-family: var(--serif);
  font-weight: 600;
  line-height: 1.25;
  letter-spacing: -0.01em;
  color: var(--text);
}
h1 { font-size: clamp(2rem, 4vw, 2.75rem); margin: 0 0 0.5rem; }
h2 { font-size: 1.65rem; margin: 2.5rem 0 1rem; }
h3 { font-size: 1.25rem; margin: 1.75rem 0 0.5rem; }
h4 { font-size: 1.1rem; margin: 1.25rem 0 0.5rem; }
h5 { font-size: 1rem; margin: 1rem 0 0.5rem; color: var(--text-muted); font-weight: 600; text-transform: uppercase; letter-spacing: 0.06em; font-family: var(--sans); }

p { margin: 0 0 1rem; }

ul, ol { padding-left: 1.25rem; }
li { margin-bottom: 0.4rem; }

img { max-width: 100%; height: auto; display: block; }

/* Layout */
.nav {
  position: sticky;
  top: 0;
  z-index: 50;
  background: color-mix(in srgb, var(--bg) 92%, transparent);
  backdrop-filter: saturate(180%) blur(12px);
  -webkit-backdrop-filter: saturate(180%) blur(12px);
  border-bottom: 1px solid var(--border-soft);
}
.nav-inner {
  max-width: var(--max-width);
  margin: 0 auto;
  padding: 0.9rem 1.5rem;
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 1.5rem;
}
.brand {
  font-family: var(--serif);
  font-size: 1.1rem;
  font-weight: 600;
  color: var(--text);
  border: none;
}
.brand:hover { color: var(--accent); }
.nav-links { display: flex; gap: 1.5rem; list-style: none; margin: 0; padding: 0; }
.nav-links a {
  color: var(--text-muted);
  font-size: 0.95rem;
  border: none;
  padding: 0.25rem 0;
  position: relative;
}
.nav-links a:hover { color: var(--text); }
.nav-links a.active { color: var(--text); }
.nav-links a.active::after {
  content: "";
  position: absolute;
  left: 0; right: 0; bottom: -0.4rem;
  height: 2px;
  background: var(--accent);
  border-radius: 2px;
}

main {
  max-width: var(--max-width);
  margin: 0 auto;
  padding: 3rem 1.5rem 5rem;
}

/* Hero (index) */
.hero {
  display: grid;
  grid-template-columns: 1.5fr 1fr;
  gap: 3rem;
  align-items: center;
  margin-bottom: 3rem;
}
.hero-text .role {
  font-size: 1.05rem;
  color: var(--text-muted);
  margin-bottom: 1.25rem;
}
.hero-text .role a { color: var(--text-soft); }
.hero-photo {
  width: 100%;
  max-width: 260px;
  margin-left: auto;
  border-radius: var(--radius);
  box-shadow: var(--shadow);
  overflow: hidden;
  line-height: 0;
}
.hero-photo img { width: 100%; height: auto; }

@media (max-width: 720px) {
  .hero { grid-template-columns: 1fr; gap: 1.5rem; }
  .hero-photo { max-width: 220px; margin: 0 auto; }
}

/* Contact list */
.contact-list {
  display: grid;
  grid-template-columns: max-content 1fr;
  gap: 0.4rem 1.25rem;
  margin: 1.5rem 0 0;
  font-size: 0.95rem;
}
.contact-list dt {
  color: var(--text-soft);
  font-size: 0.78rem;
  letter-spacing: 0.08em;
  text-transform: uppercase;
  font-weight: 600;
  padding-top: 0.18rem;
}
.contact-list dd { margin: 0; color: var(--text-muted); }

/* Section card */
.card {
  background: var(--surface);
  border: 1px solid var(--border-soft);
  border-radius: var(--radius);
  padding: 1.75rem 2rem;
  box-shadow: var(--shadow);
  margin-bottom: 1.5rem;
}

/* Tags */
.tags { display: flex; flex-wrap: wrap; gap: 0.5rem; margin: 0.75rem 0 0; padding: 0; list-style: none; }
.tags li {
  font-size: 0.82rem;
  background: color-mix(in srgb, var(--accent) 8%, transparent);
  color: var(--accent);
  padding: 0.25rem 0.7rem;
  border-radius: 999px;
  margin: 0;
}

/* Research project block */
.project {
  display: grid;
  grid-template-columns: 1.3fr 1fr;
  gap: 2rem;
  align-items: start;
  margin: 2rem 0;
  padding-bottom: 2rem;
  border-bottom: 1px solid var(--border-soft);
}
.project:last-child { border-bottom: none; }
.project.reverse { grid-template-columns: 1fr 1.3fr; }
.project.reverse .project-text { order: 2; }
.project-figure img {
  border-radius: var(--radius-sm);
  box-shadow: var(--shadow);
}
@media (max-width: 720px) {
  .project, .project.reverse { grid-template-columns: 1fr; gap: 1rem; }
  .project.reverse .project-text { order: 0; }
}

/* Achievement list */
.pub-list { padding-left: 1.5rem; }
.pub-list li {
  margin-bottom: 0.85rem;
  line-height: 1.55;
  color: var(--text-muted);
}
.pub-list li::marker { color: var(--text-soft); }
.pub-list b { color: var(--accent); font-weight: 600; }

/* Awards */
.award-list { list-style: none; padding: 0; }
.award-list li {
  padding: 0.85rem 1rem;
  background: var(--surface);
  border: 1px solid var(--border-soft);
  border-left: 3px solid var(--accent);
  border-radius: var(--radius-sm);
  margin-bottom: 0.6rem;
  color: var(--text-muted);
  font-size: 0.95rem;
}
.award-list b { color: var(--accent); }

/* Footer */
footer {
  border-top: 1px solid var(--border-soft);
  padding: 2rem 1.5rem;
  text-align: center;
  color: var(--text-soft);
  font-size: 0.85rem;
}

/* Section heading line */
.section-title {
  display: flex;
  align-items: center;
  gap: 1rem;
  margin: 3rem 0 1.5rem;
}
.section-title h2 { margin: 0; }
.section-title::after {
  content: "";
  flex: 1;
  height: 1px;
  background: var(--border);
}

/* Lead text */
.lead {
  font-size: 1.05rem;
  color: var(--text-muted);
  max-width: 65ch;
}

/* External link icon */
a.ext::after {
  content: " ↗";
  font-size: 0.85em;
  color: var(--text-soft);
}

/* Career / timeline list */
.career {
  display: grid;
  grid-template-columns: max-content 1fr;
  gap: 0.55rem 1.25rem;
  margin: 0;
}
.career dt {
  color: var(--text-muted);
  font-weight: 600;
  white-space: nowrap;
}
.career dd { margin: 0; }
@media (max-width: 520px) {
  .career { grid-template-columns: 1fr; gap: 0.15rem 0; }
  .career dt { padding-top: 0.5rem; }
}