/* ── Reset & Base ────────────────────────────────── */
*, *::before, *::after { box-sizing: border-box; margin: 0; padding: 0; }

:root {
  --bg: #ffffff;
  --surface: #f8f9fa;
  --border: #e9ecef;
  --text: #212529;
  --text-muted: #6c757d;
  --accent: #2563eb;
  --accent-light: #eff6ff;
  --font: 'Inter', system-ui, sans-serif;
  --radius: 8px;
  --max-w: 860px;
}

html { scroll-behavior: smooth; }

body {
  font-family: var(--font);
  font-size: 16px;
  line-height: 1.7;
  color: var(--text);
  background: var(--bg);
}

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

.container {
  max-width: var(--max-w);
  margin: 0 auto;
  padding: 0 24px;
}

/* ── Nav ────────────────────────────────────────── */
nav {
  position: sticky;
  top: 0;
  z-index: 100;
  background: rgba(255, 255, 255, 0.92);
  backdrop-filter: blur(8px);
  border-bottom: 1px solid var(--border);
}

.nav-inner {
  max-width: var(--max-w);
  margin: 0 auto;
  padding: 0 24px;
  display: flex;
  align-items: center;
  justify-content: space-between;
  height: 56px;
}

.nav-name {
  font-weight: 600;
  font-size: 0.95rem;
  letter-spacing: -0.01em;
}

nav ul {
  list-style: none;
  display: flex;
  gap: 28px;
}

nav ul a {
  font-size: 0.9rem;
  color: var(--text-muted);
  font-weight: 400;
  transition: color 0.15s;
}

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

/* ── Hero ───────────────────────────────────────── */
.hero {
  padding: 72px 0 64px;
  border-bottom: 1px solid var(--border);
}

.hero-inner {
  display: flex;
  align-items: center;
  gap: 48px;
}

.hero-text { flex: 1; }

h1 {
  font-size: 2rem;
  font-weight: 600;
  letter-spacing: -0.03em;
  margin-bottom: 6px;
}

.affiliation {
  font-size: 0.9rem;
  color: var(--text-muted);
  margin-bottom: 20px;
  line-height: 1.5;
}

.bio {
  font-size: 0.97rem;
  color: var(--text);
  max-width: 520px;
  margin-bottom: 24px;
}

.bio strong { color: var(--text); font-weight: 600; }

.links {
  display: flex;
  flex-wrap: wrap;
  gap: 10px;
}

.links a {
  display: inline-block;
  padding: 6px 14px;
  border: 1px solid var(--border);
  border-radius: 20px;
  font-size: 0.84rem;
  font-weight: 500;
  color: var(--text);
  transition: border-color 0.15s, color 0.15s;
}

.links a:hover {
  border-color: var(--accent);
  color: var(--accent);
  text-decoration: none;
}

/* Photo placeholder */
.hero-photo { flex-shrink: 0; }

.photo-placeholder {
  width: 120px;
  height: 120px;
  border-radius: 50%;
  background: var(--accent-light);
  border: 2px solid var(--border);
  display: flex;
  align-items: center;
  justify-content: center;
  font-size: 1.4rem;
  font-weight: 600;
  color: var(--accent);
  letter-spacing: -0.02em;
}

/* Photo (when you add one) */
.hero-photo img {
  width: 120px;
  height: 120px;
  border-radius: 50%;
  object-fit: cover;
  border: 2px solid var(--border);
}

/* ── Sections ───────────────────────────────────── */
section { padding: 60px 0; border-bottom: 1px solid var(--border); }

h2 {
  font-size: 1.25rem;
  font-weight: 600;
  letter-spacing: -0.02em;
  margin-bottom: 32px;
}

/* ── Timeline ───────────────────────────────────── */
.timeline {
  display: flex;
  flex-direction: column;
  gap: 0;
  border-left: 2px solid var(--border);
  margin-left: 8px;
  padding-left: 0;
}

.tl-item {
  display: flex;
  gap: 24px;
  padding: 0 0 28px 28px;
  position: relative;
}

.tl-item::before {
  content: '';
  position: absolute;
  left: -5px;
  top: 6px;
  width: 8px;
  height: 8px;
  border-radius: 50%;
  background: var(--accent);
  border: 2px solid var(--bg);
  outline: 2px solid var(--accent);
}

.tl-date {
  min-width: 160px;
  font-size: 0.82rem;
  color: var(--text-muted);
  font-weight: 500;
  padding-top: 2px;
  flex-shrink: 0;
}

.tl-content { flex: 1; }

.tl-title {
  font-size: 0.95rem;
  font-weight: 600;
  color: var(--text);
  margin-bottom: 2px;
}

.tl-place {
  font-size: 0.85rem;
  color: var(--text-muted);
}

.tl-sub {
  margin-top: 12px;
  margin-left: 4px;
  display: flex;
  flex-direction: column;
  gap: 0;
  border-left: 2px solid var(--border);
  padding-left: 0;
}

.tl-sub-item {
  display: flex;
  gap: 16px;
  padding: 0 0 14px 22px;
  position: relative;
  font-size: 0.82rem;
  color: var(--text-muted);
}

.tl-sub-item:last-child {
  padding-bottom: 4px;
}

.tl-sub-item::before {
  content: '';
  position: absolute;
  left: -4px;
  top: 5px;
  width: 6px;
  height: 6px;
  border-radius: 50%;
  background: var(--bg);
  border: 2px solid var(--text-muted);
}

.tl-sub-date {
  flex-shrink: 0;
  min-width: 120px;
  font-weight: 500;
}

.tl-sub-title {
  flex: 1;
}

/* ── Publications ───────────────────────────────── */
.pub-category {
  font-size: 0.75rem;
  font-weight: 600;
  text-transform: uppercase;
  letter-spacing: 0.08em;
  color: var(--text-muted);
  margin-bottom: 14px;
  padding-bottom: 6px;
  border-bottom: 1px solid var(--border);
}

.pub-list + .pub-category {
  margin-top: 28px;
}

.pub-list {
  display: flex;
  flex-direction: column;
  gap: 28px;
}

.pub-item {
  display: flex;
  gap: 24px;
  padding: 20px;
  border-radius: var(--radius);
  border: 1px solid var(--border);
  transition: border-color 0.15s;
}

.pub-item:hover { border-color: #adb5bd; }

.pub-item.highlight {
  border-color: var(--accent);
  background: var(--accent-light);
}

.pub-year {
  min-width: 44px;
  font-size: 0.82rem;
  font-weight: 500;
  color: var(--text-muted);
  padding-top: 2px;
}

.pub-content { flex: 1; }

.pub-title {
  font-size: 0.97rem;
  font-weight: 600;
  line-height: 1.4;
  margin-bottom: 4px;
  color: var(--text);
}

.pub-authors {
  font-size: 0.85rem;
  color: var(--text-muted);
  margin-bottom: 4px;
}

.pub-venue {
  font-size: 0.84rem;
  color: var(--text-muted);
  margin-bottom: 10px;
  display: flex;
  align-items: center;
  gap: 8px;
  flex-wrap: wrap;
}

.venue-badge {
  display: inline-block;
  padding: 2px 8px;
  border-radius: 4px;
  font-size: 0.75rem;
  font-weight: 600;
  letter-spacing: 0.02em;
}

.venue-badge.conference {
  background: #dbeafe;
  color: #1d4ed8;
}

.venue-badge.workshop {
  background: #fef3c7;
  color: #92400e;
}

.pub-note {
  font-size: 0.82rem;
  color: var(--text-muted);
  font-style: italic;
  margin-top: 4px;
}

.pub-links {
  display: flex;
  gap: 10px;
}

.pub-links a {
  font-size: 0.8rem;
  font-weight: 500;
  padding: 3px 10px;
  border: 1px solid var(--accent);
  border-radius: 4px;
  color: var(--accent);
  transition: background 0.15s;
}

.pub-links a:hover {
  background: var(--accent);
  color: #fff;
  text-decoration: none;
}

/* ── Contact ────────────────────────────────────── */
#contact p { font-size: 0.97rem; }

/* ── Footer ─────────────────────────────────────── */
footer {
  padding: 32px 0;
  border-top: none;
}

footer p {
  font-size: 0.82rem;
  color: var(--text-muted);
}

/* ── i18n ──────────────────────────────────────── */
body.lang-en .i18n-ja { display: none; }
body.lang-ja .i18n-en { display: none; }

.lang-toggle {
  background: none;
  border: 1px solid var(--border);
  border-radius: 4px;
  padding: 4px 10px;
  font-family: var(--font);
  font-size: 0.8rem;
  font-weight: 600;
  color: var(--text-muted);
  cursor: pointer;
  transition: border-color 0.15s, color 0.15s;
  margin-left: 12px;
  flex-shrink: 0;
}

.lang-toggle:hover {
  border-color: var(--accent);
  color: var(--accent);
}

/* ── Hamburger ──────────────────────────────────── */
.nav-toggle {
  display: none;
  flex-direction: column;
  justify-content: center;
  gap: 5px;
  width: 36px;
  height: 36px;
  background: none;
  border: none;
  cursor: pointer;
  padding: 4px;
  border-radius: var(--radius);
}

.nav-toggle span {
  display: block;
  width: 22px;
  height: 2px;
  background: var(--text);
  border-radius: 2px;
  transition: all 0.25s;
}

.nav-toggle.open span:nth-child(1) {
  transform: translateY(7px) rotate(45deg);
}
.nav-toggle.open span:nth-child(2) {
  opacity: 0;
  transform: scaleX(0);
}
.nav-toggle.open span:nth-child(3) {
  transform: translateY(-7px) rotate(-45deg);
}

/* ── Responsive ─────────────────────────────────── */
@media (max-width: 640px) {
  /* Nav */
  .nav-toggle { display: flex; }

  nav ul {
    display: none;
    position: absolute;
    top: 56px;
    left: 0;
    right: 0;
    flex-direction: column;
    gap: 0;
    background: rgba(255, 255, 255, 0.97);
    backdrop-filter: blur(8px);
    border-bottom: 1px solid var(--border);
    padding: 8px 0;
    z-index: 99;
  }

  nav ul.open { display: flex; }

  nav ul li a {
    display: block;
    padding: 12px 24px;
    font-size: 0.95rem;
  }

  /* Hero */
  .hero { padding: 40px 0 36px; }
  .hero-inner {
    flex-direction: column;
    align-items: center;
    gap: 20px;
    text-align: center;
  }

  .hero-photo { order: -1; }
  .photo-placeholder, .hero-photo img { width: 96px; height: 96px; }

  h1 { font-size: 1.7rem; }

  .affiliation { font-size: 0.85rem; }

  .bio { max-width: 100%; font-size: 0.93rem; }

  .links { justify-content: center; }

  /* Sections */
  section { padding: 40px 0; }

  /* Timeline */
  .tl-item {
    flex-direction: column;
    gap: 2px;
    padding: 0 0 24px 24px;
  }
  .tl-date { min-width: unset; font-size: 0.8rem; }
  .tl-title { font-size: 0.9rem; }

  .tl-sub-item {
    flex-direction: column;
    gap: 2px;
    padding: 0 0 12px 18px;
  }
  .tl-sub-date { min-width: unset; }

  /* Publications */
  .pub-item {
    flex-direction: column;
    gap: 6px;
    padding: 14px;
  }
  .pub-year { min-width: unset; font-size: 0.78rem; }
  .pub-title { font-size: 0.92rem; }
  .pub-venue { flex-wrap: wrap; font-size: 0.8rem; }
}