/* ===== RESET & BASE ===== */
*, *::before, *::after {
  box-sizing: border-box;
  margin: 0;
  padding: 0;
}

:root {
  --primary:      #003366;
  --primary-light:#004a99;
  --accent:       #c8960c;
  --text:         #1a1a2e;
  --text-muted:   #555;
  --bg:           #ffffff;
  --bg-alt:       #f5f7fa;
  --border:       #dde3ec;
  --nav-height:   64px;
  --max-width:    960px;
  --radius:       6px;
  --shadow:       0 2px 12px rgba(0,0,0,0.08);
  --transition:   0.2s ease;
}

html {
  font-size: 16px;
  scroll-behavior: smooth;
}

body {
  font-family: 'Georgia', 'Times New Roman', serif;
  color: var(--text);
  background: var(--bg);
  line-height: 1.75;
}

a {
  color: var(--primary-light);
  text-decoration: none;
  transition: color var(--transition);
}

a:hover { color: var(--accent); }

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

/* ===== NAVIGATION ===== */
nav {
  position: sticky;
  top: 0;
  z-index: 100;
  background: var(--primary);
  height: var(--nav-height);
  box-shadow: 0 2px 8px rgba(0,0,0,0.2);
}

.nav-inner {
  max-width: var(--max-width);
  margin: 0 auto;
  padding: 0 1.5rem;
  height: 100%;
  display: flex;
  align-items: center;
  justify-content: space-between;
}

.nav-brand {
  color: #fff;
  font-size: 1.05rem;
  font-weight: bold;
  letter-spacing: 0.02em;
  white-space: nowrap;
}

.nav-brand span {
  color: var(--accent);
}

.nav-links {
  list-style: none;
  display: flex;
  gap: 0.25rem;
}

.visit-ct { font-family:'Helvetica Neue',Arial,sans-serif; font-size:.72rem; color:rgba(255,255,255,.55); letter-spacing:.04em; white-space:nowrap; }
.visit-ct strong { color:var(--accent); font-weight:700; }

.nav-links a {
  color: rgba(255,255,255,0.85);
  font-family: 'Helvetica Neue', Arial, sans-serif;
  font-size: 0.875rem;
  letter-spacing: 0.04em;
  padding: 0.4rem 0.75rem;
  border-radius: var(--radius);
  transition: background var(--transition), color var(--transition);
}

.nav-links a:hover,
.nav-links a.active {
  background: rgba(255,255,255,0.12);
  color: #fff;
}

.nav-links a.active {
  border-bottom: 2px solid var(--accent);
}

/* Hamburger */
.hamburger {
  display: none;
  flex-direction: column;
  gap: 5px;
  cursor: pointer;
  padding: 4px;
  background: none;
  border: none;
}

.hamburger span {
  display: block;
  width: 24px;
  height: 2px;
  background: #fff;
  border-radius: 2px;
  transition: transform var(--transition), opacity var(--transition);
}

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

/* ===== PAGE WRAPPER ===== */
.page {
  min-height: calc(100vh - var(--nav-height) - 80px);
}

.container {
  max-width: var(--max-width);
  margin: 0 auto;
  padding: 0 1.5rem;
}

/* ===== HERO (HOME) ===== */
.hero {
  background: linear-gradient(135deg, var(--primary) 0%, #00509e 100%);
  color: #fff;
  padding: 5rem 1.5rem 4rem;
}

.hero-inner {
  max-width: var(--max-width);
  margin: 0 auto;
  display: flex;
  align-items: center;
  gap: 3rem;
}

.hero-avatar {
  flex-shrink: 0;
  width: 170px;
  height: 170px;
  border-radius: 50%;
  background: rgba(255,255,255,0.15);
  border: 4px solid rgba(255,255,255,0.3);
  display: flex;
  align-items: center;
  justify-content: center;
  font-size: 4rem;
  color: rgba(255,255,255,0.7);
  overflow: hidden;
}

.hero-avatar img {
  width: 100%;
  height: 100%;
  object-fit: cover;
  object-position: center 35%;
  border-radius: 50%;
}

.hero-text h1 {
  font-size: 2.2rem;
  font-weight: bold;
  letter-spacing: -0.01em;
  margin-bottom: 0.5rem;
}

.hero-text .title {
  font-size: 1.05rem;
  color: var(--accent);
  font-family: 'Helvetica Neue', Arial, sans-serif;
  letter-spacing: 0.05em;
  text-transform: uppercase;
  font-weight: 600;
  margin-bottom: 0.25rem;
}

.hero-text .dept {
  font-size: 1rem;
  color: rgba(255,255,255,0.8);
  margin-bottom: 1.25rem;
}

.hero-text p {
  font-size: 1rem;
  color: rgba(255,255,255,0.85);
  max-width: 540px;
  line-height: 1.8;
}

.hero-actions {
  margin-top: 1.75rem;
  display: flex;
  gap: 1rem;
  flex-wrap: wrap;
}

.btn {
  font-family: 'Helvetica Neue', Arial, sans-serif;
  font-size: 0.875rem;
  font-weight: 600;
  letter-spacing: 0.04em;
  padding: 0.65rem 1.4rem;
  border-radius: var(--radius);
  cursor: pointer;
  transition: all var(--transition);
  border: 2px solid transparent;
  display: inline-block;
}

.btn-primary {
  background: var(--accent);
  color: var(--primary);
  border-color: var(--accent);
}

.btn-primary:hover {
  background: #b5850a;
  border-color: #b5850a;
  color: #fff;
}

.btn-outline {
  background: transparent;
  color: #fff;
  border-color: rgba(255,255,255,0.5);
}

.btn-outline:hover {
  background: rgba(255,255,255,0.1);
  border-color: #fff;
  color: #fff;
}

/* ===== SECTION TITLES ===== */
.section {
  padding: 4rem 0;
}

.section-alt {
  background: var(--bg-alt);
}

.section-title {
  font-size: 1.6rem;
  color: var(--primary);
  margin-bottom: 0.5rem;
  padding-bottom: 0.5rem;
  border-bottom: 3px solid var(--accent);
  display: inline-block;
}

.section-subtitle {
  color: var(--text-muted);
  font-size: 0.95rem;
  margin-bottom: 2rem;
  font-family: 'Helvetica Neue', Arial, sans-serif;
}

/* ===== CARDS ===== */
.card-grid {
  display: grid;
  grid-template-columns: repeat(auto-fill, minmax(280px, 1fr));
  gap: 1.25rem;
  margin-top: 2rem;
}

.card {
  background: var(--bg);
  border: 1px solid var(--border);
  border-radius: var(--radius);
  padding: 1.5rem;
  box-shadow: var(--shadow);
  transition: transform var(--transition), box-shadow var(--transition);
}

.card:hover {
  transform: translateY(-3px);
  box-shadow: 0 6px 20px rgba(0,0,0,0.12);
}

.card h3 {
  color: var(--primary);
  font-size: 1rem;
  margin-bottom: 0.4rem;
}

.card p {
  font-size: 0.9rem;
  color: var(--text-muted);
  font-family: 'Helvetica Neue', Arial, sans-serif;
}

/* ===== INFO ITEMS (about page) ===== */
.info-grid {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: 2rem;
  margin-top: 2rem;
}

.info-block h3 {
  font-size: 1.1rem;
  color: var(--primary);
  margin-bottom: 1rem;
  font-family: 'Helvetica Neue', Arial, sans-serif;
  text-transform: uppercase;
  letter-spacing: 0.06em;
  font-size: 0.8rem;
}

.info-block ul {
  list-style: none;
}

.info-block li {
  padding: 0.6rem 0;
  border-bottom: 1px solid var(--border);
  font-size: 0.95rem;
}

.info-block li:last-child { border-bottom: none; }

.info-block li strong {
  display: block;
  color: var(--primary);
  font-size: 0.9rem;
}

.info-block li span {
  color: var(--text-muted);
  font-size: 0.875rem;
  font-family: 'Helvetica Neue', Arial, sans-serif;
}

/* ===== TEACHING ===== */
.course-table {
  width: 100%;
  border-collapse: collapse;
  margin-top: 1.5rem;
  font-family: 'Helvetica Neue', Arial, sans-serif;
  font-size: 0.9rem;
}

.course-table th {
  background: var(--primary);
  color: #fff;
  padding: 0.75rem 1rem;
  text-align: left;
  font-weight: 600;
  letter-spacing: 0.04em;
  font-size: 0.8rem;
  text-transform: uppercase;
}

.course-table th:first-child { border-radius: var(--radius) 0 0 0; }
.course-table th:last-child  { border-radius: 0 var(--radius) 0 0; }

.course-table td {
  padding: 0.75rem 1rem;
  border-bottom: 1px solid var(--border);
  vertical-align: top;
}

.course-table tr:last-child td { border-bottom: none; }

.course-table tr:nth-child(even) td {
  background: var(--bg-alt);
}

.course-table tr:hover td {
  background: #eef3fb;
}

.course-code {
  font-weight: bold;
  color: var(--primary);
  white-space: nowrap;
}

.course-tag {
  display: inline-block;
  padding: 0.2rem 0.5rem;
  border-radius: 3px;
  font-size: 0.75rem;
  font-weight: 600;
}

.tag-intro    { background: #e3f0ff; color: #1a5db0; }
.tag-inter    { background: #fff3cd; color: #856404; }
.tag-upper    { background: #d4edda; color: #155724; }
.tag-grad     { background: #f8d7da; color: #721c24; }

/* ===== RESEARCH ===== */
.research-areas {
  display: grid;
  grid-template-columns: repeat(auto-fill, minmax(250px, 1fr));
  gap: 1rem;
  margin-top: 2rem;
}

.research-area {
  background: var(--bg);
  border-left: 4px solid var(--accent);
  border-radius: 0 var(--radius) var(--radius) 0;
  padding: 1.2rem 1.4rem;
  box-shadow: var(--shadow);
}

.research-area h3 {
  color: var(--primary);
  font-size: 0.95rem;
  margin-bottom: 0.4rem;
}

.research-area p {
  font-size: 0.875rem;
  color: var(--text-muted);
  font-family: 'Helvetica Neue', Arial, sans-serif;
  line-height: 1.6;
}

.paper-list {
  margin-top: 1.5rem;
  display: flex;
  flex-direction: column;
  gap: 1.25rem;
}

.paper-item {
  background: var(--bg);
  border: 1px solid var(--border);
  border-radius: var(--radius);
  padding: 1.4rem 1.6rem;
  box-shadow: var(--shadow);
}

.paper-item .paper-title {
  font-size: 1rem;
  color: var(--primary);
  font-weight: bold;
  margin-bottom: 0.3rem;
}

.paper-item .paper-meta {
  font-size: 0.85rem;
  color: var(--text-muted);
  font-family: 'Helvetica Neue', Arial, sans-serif;
  margin-bottom: 0.5rem;
}

.paper-item .paper-abstract {
  font-size: 0.9rem;
  color: var(--text);
  line-height: 1.7;
}

.paper-status {
  display: inline-block;
  padding: 0.2rem 0.6rem;
  border-radius: 3px;
  font-size: 0.75rem;
  font-weight: 700;
  font-family: 'Helvetica Neue', Arial, sans-serif;
  letter-spacing: 0.04em;
  margin-left: 0.5rem;
}

.status-working  { background: #fff3cd; color: #856404; }
.status-progress { background: #cfe2ff; color: #084298; }
.status-revision { background: #d4edda; color: #155724; }

/* ===== PUBLICATIONS ===== */
.pub-list {
  margin-top: 1.5rem;
  counter-reset: pub-counter;
}

.pub-year-group { margin-bottom: 2.5rem; }

.pub-year-label {
  font-size: 1.1rem;
  font-weight: bold;
  color: var(--primary);
  font-family: 'Helvetica Neue', Arial, sans-serif;
  border-bottom: 2px solid var(--accent);
  padding-bottom: 0.3rem;
  margin-bottom: 1rem;
}

.pub-entry {
  padding: 1rem 1.2rem;
  border-left: 3px solid var(--border);
  margin-bottom: 1rem;
  font-size: 0.93rem;
  line-height: 1.75;
  transition: border-color var(--transition);
}

.pub-entry:hover {
  border-left-color: var(--accent);
}

.pub-entry .pub-authors {
  color: var(--text-muted);
  font-family: 'Helvetica Neue', Arial, sans-serif;
  font-size: 0.875rem;
}

.pub-entry .pub-title {
  font-weight: bold;
  color: var(--primary);
}

.pub-entry .pub-journal {
  font-style: italic;
  color: var(--text);
}

.pub-entry .pub-links {
  margin-top: 0.4rem;
  display: flex;
  gap: 0.75rem;
  flex-wrap: wrap;
}

.pub-link {
  font-size: 0.8rem;
  font-family: 'Helvetica Neue', Arial, sans-serif;
  padding: 0.2rem 0.6rem;
  border: 1px solid var(--primary-light);
  border-radius: 3px;
  color: var(--primary-light);
  transition: all var(--transition);
}

.pub-link:hover {
  background: var(--primary-light);
  color: #fff;
}

/* ===== CONTACT ===== */
.contact-grid {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: 3rem;
  margin-top: 2rem;
}

.contact-info h3 {
  font-size: 1rem;
  color: var(--primary);
  font-family: 'Helvetica Neue', Arial, sans-serif;
  text-transform: uppercase;
  letter-spacing: 0.06em;
  font-size: 0.8rem;
  margin-bottom: 1.25rem;
}

.contact-item {
  display: flex;
  align-items: flex-start;
  gap: 1rem;
  margin-bottom: 1.25rem;
}

.contact-icon {
  width: 36px;
  height: 36px;
  background: var(--primary);
  color: #fff;
  border-radius: 50%;
  display: flex;
  align-items: center;
  justify-content: center;
  font-size: 0.9rem;
  flex-shrink: 0;
}

.contact-detail strong {
  display: block;
  font-size: 0.85rem;
  color: var(--text-muted);
  font-family: 'Helvetica Neue', Arial, sans-serif;
  text-transform: uppercase;
  letter-spacing: 0.05em;
  margin-bottom: 0.15rem;
}

.contact-detail span, .contact-detail a {
  font-size: 0.95rem;
  color: var(--text);
}

.contact-detail a:hover { color: var(--accent); }

.contact-form {
  background: var(--bg-alt);
  border: 1px solid var(--border);
  border-radius: var(--radius);
  padding: 2rem;
}

.contact-form h3 {
  font-size: 1.1rem;
  color: var(--primary);
  margin-bottom: 1.5rem;
}

.form-group {
  margin-bottom: 1.25rem;
}

.form-group label {
  display: block;
  font-size: 0.85rem;
  font-family: 'Helvetica Neue', Arial, sans-serif;
  color: var(--text-muted);
  margin-bottom: 0.4rem;
  letter-spacing: 0.03em;
}

.form-group input,
.form-group textarea,
.form-group select {
  width: 100%;
  padding: 0.65rem 0.9rem;
  border: 1px solid var(--border);
  border-radius: var(--radius);
  font-family: inherit;
  font-size: 0.95rem;
  color: var(--text);
  background: var(--bg);
  transition: border-color var(--transition), box-shadow var(--transition);
  outline: none;
}

.form-group input:focus,
.form-group textarea:focus,
.form-group select:focus {
  border-color: var(--primary-light);
  box-shadow: 0 0 0 3px rgba(0, 74, 153, 0.1);
}

.form-group textarea { min-height: 130px; resize: vertical; }

.form-submit {
  background: var(--primary);
  color: #fff;
  border: none;
  padding: 0.75rem 2rem;
  border-radius: var(--radius);
  font-family: 'Helvetica Neue', Arial, sans-serif;
  font-size: 0.9rem;
  font-weight: 600;
  letter-spacing: 0.04em;
  cursor: pointer;
  transition: background var(--transition);
  width: 100%;
}

.form-submit:hover { background: var(--primary-light); }

/* ===== PAGE HEADER ===== */
.page-header {
  background: var(--primary);
  color: #fff;
  padding: 3rem 1.5rem 2.5rem;
}

.page-header-inner {
  max-width: var(--max-width);
  margin: 0 auto;
}

.page-header h1 {
  font-size: 2rem;
  margin-bottom: 0.35rem;
}

.page-header p {
  color: rgba(255,255,255,0.75);
  font-family: 'Helvetica Neue', Arial, sans-serif;
  font-size: 0.95rem;
}

.breadcrumb {
  font-family: 'Helvetica Neue', Arial, sans-serif;
  font-size: 0.8rem;
  color: rgba(255,255,255,0.5);
  margin-bottom: 0.5rem;
}

.breadcrumb a { color: rgba(255,255,255,0.65); }
.breadcrumb a:hover { color: var(--accent); }
.breadcrumb span { margin: 0 0.4rem; }

/* ===== FOOTER ===== */
footer {
  background: var(--primary);
  color: rgba(255,255,255,0.7);
  padding: 2.5rem 1.5rem;
  font-family: 'Helvetica Neue', Arial, sans-serif;
  font-size: 0.85rem;
}

.footer-inner {
  max-width: var(--max-width);
  margin: 0 auto;
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 1rem;
  flex-wrap: wrap;
}

.footer-inner a { color: rgba(255,255,255,0.65); }
.footer-inner a:hover { color: var(--accent); }

.footer-right { text-align: right; }

/* ===== NOTICE / PLACEHOLDER ===== */
.notice {
  background: #fff8e1;
  border: 1px solid #ffe082;
  border-left: 4px solid var(--accent);
  border-radius: var(--radius);
  padding: 1rem 1.25rem;
  font-size: 0.9rem;
  color: #5a4000;
  font-family: 'Helvetica Neue', Arial, sans-serif;
  margin-top: 1.5rem;
}

/* ===== UTILITY ===== */
.text-muted { color: var(--text-muted); }
.mt-1 { margin-top: 0.5rem; }
.mt-2 { margin-top: 1rem; }
.mt-3 { margin-top: 1.5rem; }
.mt-4 { margin-top: 2rem; }

/* ===== RESPONSIVE ===== */
@media (max-width: 768px) {
  .hamburger { display: flex; }

  .nav-links {
    display: none;
    position: absolute;
    top: var(--nav-height);
    left: 0;
    right: 0;
    background: var(--primary);
    flex-direction: column;
    padding: 0.75rem 1rem 1.25rem;
    gap: 0.25rem;
    box-shadow: 0 4px 12px rgba(0,0,0,0.2);
  }

  .nav-links.open { display: flex; }

  .nav-links a {
    padding: 0.6rem 0.9rem;
    font-size: 0.95rem;
  }

  .hero-inner {
    flex-direction: column;
    text-align: center;
    gap: 2rem;
  }

  .hero-actions { justify-content: center; }

  .hero-text h1 { font-size: 1.7rem; }

  .info-grid    { grid-template-columns: 1fr; }
  .contact-grid { grid-template-columns: 1fr; }

  .course-table { font-size: 0.82rem; }
  .course-table th, .course-table td { padding: 0.6rem 0.65rem; }

  .footer-inner { flex-direction: column; text-align: center; }
  .footer-right { text-align: center; }

  .page-header h1 { font-size: 1.6rem; }
}

@media (max-width: 500px) {
  .hero { padding: 3rem 1.25rem 2.5rem; }
  .hero-avatar { width: 130px; height: 130px; font-size: 3rem; }
  .section { padding: 2.5rem 0; }
  .card-grid { grid-template-columns: 1fr; }
  .research-areas { grid-template-columns: 1fr; }
}