:root {
  --color-bg: #ffffff;
  --color-text: #1a1f2c;
  --color-muted: #5a6475;
  --color-primary: #0b4f8a;
  --color-primary-dark: #08406f;
  --color-accent: #f4b400;
  --color-surface: #f5f7fb;
  --color-border: #e3e8f0;
  --radius: 10px;
  --shadow-sm: 0 1px 2px rgba(15, 23, 42, 0.06);
  --shadow-md: 0 6px 20px rgba(15, 23, 42, 0.08);
  --max-width: 1100px;
  --font-sans: -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, Oxygen,
    Ubuntu, Cantarell, "Helvetica Neue", sans-serif;
}

* {
  box-sizing: border-box;
}

html, body {
  margin: 0;
  padding: 0;
}

body {
  font-family: var(--font-sans);
  color: var(--color-text);
  background: var(--color-bg);
  line-height: 1.6;
  -webkit-font-smoothing: antialiased;
}

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

.container {
  max-width: var(--max-width);
  margin: 0 auto;
  padding: 0 1.25rem;
}

/* Header */
.site-header {
  background: #fff;
  border-bottom: 1px solid var(--color-border);
  position: sticky;
  top: 0;
  z-index: 10;
}
.header-inner {
  display: flex;
  align-items: center;
  justify-content: space-between;
  padding: 1rem 1.25rem;
}
.brand {
  display: flex;
  align-items: center;
  gap: 0.6rem;
  font-weight: 700;
  color: var(--color-text);
}
.brand:hover { text-decoration: none; }
.brand-text { font-size: 1.05rem; }

.main-nav {
  display: flex;
  gap: 1.25rem;
  flex-wrap: wrap;
}
.main-nav a {
  color: var(--color-text);
  font-weight: 500;
  padding: 0.35rem 0;
  border-bottom: 2px solid transparent;
}
.main-nav a:hover { color: var(--color-primary); text-decoration: none; }
.main-nav a.active {
  color: var(--color-primary);
  border-bottom-color: var(--color-primary);
}

/* Hero */
.hero {
  background: linear-gradient(135deg, #0b4f8a 0%, #0a3a68 100%);
  color: #fff;
  padding: 4.5rem 0 4rem;
}
.hero-inner {
  display: flex;
  align-items: center;
  gap: 2.5rem;
}
.hero-logo {
  width: 280px;
  height: 280px;
  object-fit: contain;
  flex-shrink: 0;
  background: rgba(255, 255, 255, 0.08);
  border-radius: 50%;
  padding: 0.5rem;
}
.hero-body { min-width: 0; flex: 1; }
@media (max-width: 720px) {
  .hero-inner { flex-direction: column; align-items: flex-start; gap: 1.5rem; }
  .hero-logo { width: 196px; height: 196px; }
}
.hero .eyebrow {
  text-transform: uppercase;
  letter-spacing: 0.12em;
  font-size: 0.8rem;
  opacity: 0.85;
  margin: 0;
}
.hero h1 {
  font-size: clamp(2rem, 4vw, 3rem);
  margin: 0.3rem 0 0.75rem;
  line-height: 1.15;
}
.hero .lead {
  font-size: 1.1rem;
  opacity: 0.92;
  margin: 0 0 1rem;
}
.hero-copy {
  max-width: 720px;
  opacity: 0.9;
}
.hero-cta {
  margin-top: 1.5rem;
  display: flex;
  gap: 0.75rem;
  flex-wrap: wrap;
}

/* Buttons */
.btn {
  display: inline-block;
  padding: 0.7rem 1.2rem;
  border-radius: var(--radius);
  font-weight: 600;
  transition: transform 0.05s ease, background 0.15s ease, color 0.15s ease;
}
.btn:hover { text-decoration: none; }
.btn-primary {
  background: var(--color-accent);
  color: #1a1f2c;
}
.btn-primary:hover { background: #ffc825; }
.btn-ghost {
  background: transparent;
  color: #fff;
  border: 1px solid rgba(255, 255, 255, 0.6);
}
.btn-ghost:hover { background: rgba(255, 255, 255, 0.1); }

/* Page header */
.page-header {
  background: var(--color-surface);
  padding: 3rem 0 2.5rem;
  border-bottom: 1px solid var(--color-border);
}
.page-header h1 {
  font-size: clamp(1.75rem, 3vw, 2.25rem);
  margin: 0 0 0.5rem;
}
.page-header .lead {
  color: var(--color-muted);
  margin: 0;
}

/* Sections */
.section { padding: 3.5rem 0; }
.section-alt { background: var(--color-surface); }
.section-title {
  font-size: 1.6rem;
  margin: 0 0 0.35rem;
}
.section-sub {
  color: var(--color-muted);
  margin: 0 0 2rem;
}

/* Grid & Cards */
.grid { display: grid; gap: 1.25rem; }
.grid-1 { grid-template-columns: 1fr; }
.grid-2 { grid-template-columns: repeat(2, minmax(0, 1fr)); }
.grid-3 { grid-template-columns: repeat(3, minmax(0, 1fr)); }
.grid-4 { grid-template-columns: repeat(4, minmax(0, 1fr)); }
@media (max-width: 820px) {
  .grid-2, .grid-3 { grid-template-columns: 1fr; }
}
@media (max-width: 640px) {
  .grid-4 { grid-template-columns: repeat(2, minmax(0, 1fr)); }
}
@media (max-width: 420px) {
  .grid-4 { grid-template-columns: 1fr; }
}

.card {
  background: #fff;
  border: 1px solid var(--color-border);
  border-radius: var(--radius);
  padding: 1.4rem 1.5rem;
  box-shadow: var(--shadow-sm);
  transition: box-shadow 0.15s ease, transform 0.15s ease;
}
.card:hover { box-shadow: var(--shadow-md); transform: translateY(-2px); }
.card h2, .card h3 { margin: 0 0 0.4rem; }
.card-lead {
  color: var(--color-primary);
  font-weight: 600;
  margin: 0 0 0.5rem;
}
.card-wide { padding: 1.75rem 2rem; }
.card-small { padding: 1.2rem 1.3rem; }

/* Prose */
.prose h2 { margin-top: 2rem; }
.prose ul { padding-left: 1.25rem; }
.prose li { margin: 0.35rem 0; }

/* Footer */
.site-footer {
  background: #0a1628;
  color: #cbd5e1;
  padding: 2.5rem 0;
  margin-top: 3rem;
}
.footer-inner { text-align: center; }
.footer-title {
  color: #fff;
  font-weight: 700;
  margin: 0 0 0.25rem;
}
.footer-sub { color: #94a3b8; margin: 0 0 1rem; }
.footer-copy {
  font-size: 0.85rem;
  color: #64748b;
  margin: 0;
}

/* Responsive header stacking */
@media (max-width: 640px) {
  .header-inner {
    flex-direction: column;
    gap: 0.75rem;
    align-items: flex-start;
  }
  .main-nav { gap: 0.9rem; }
}

/* Sub-nav for Kyriakopoulos group */
.subnav {
  background: #0a1628;
  color: #cbd5e1;
  border-bottom: 1px solid #1e293b;
  position: sticky;
  top: 62px;
  z-index: 9;
}
.subnav-inner {
  display: flex;
  align-items: center;
  gap: 1.25rem;
  padding: 0.6rem 1.25rem;
  flex-wrap: wrap;
}
.subnav-label {
  color: #94a3b8;
  font-size: 0.8rem;
  text-transform: uppercase;
  letter-spacing: 0.1em;
  font-weight: 700;
}
.subnav ul {
  list-style: none;
  margin: 0;
  padding: 0;
  display: flex;
  flex-wrap: wrap;
  gap: 0.15rem;
}
.subnav ul a {
  display: inline-block;
  padding: 0.35rem 0.75rem;
  border-radius: 6px;
  color: #cbd5e1;
  font-size: 0.9rem;
  font-weight: 500;
}
.subnav ul a:hover { background: #1e293b; color: #fff; text-decoration: none; }
.subnav ul a.active { background: var(--color-accent); color: #1a1f2c; }

/* Card link variant */
.card-link { display: block; color: inherit; }
.card-link:hover { text-decoration: none; }
.card-more {
  color: var(--color-primary);
  font-weight: 600;
  margin: 0.5rem 0 0;
}

.muted { color: var(--color-muted); font-weight: 400; }

/* Image grid for research galleries */
.image-grid {
  display: grid;
  grid-template-columns: repeat(auto-fill, minmax(220px, 1fr));
  gap: 0.75rem;
  margin-top: 1rem;
}
.image-grid img {
  width: 100%;
  height: 180px;
  object-fit: cover;
  border-radius: 8px;
  border: 1px solid var(--color-border);
  background: #f1f5f9;
}

.sub-section { margin-bottom: 2.25rem; }
.sub-section:last-child { margin-bottom: 0; }

/* Equipment cards */
.equipment-card { display: flex; flex-direction: column; }
.equipment-img {
  width: 100%;
  height: 200px;
  object-fit: contain;
  background: #f1f5f9;
  border-radius: 8px;
  margin-bottom: 0.75rem;
}

/* Course cards */
.course-card { display: flex; gap: 1rem; align-items: flex-start; }
.course-img {
  width: 100px;
  height: 100px;
  object-fit: cover;
  border-radius: 8px;
  background: #f1f5f9;
  flex-shrink: 0;
}
@media (max-width: 480px) {
  .course-card { flex-direction: column; }
  .course-img { width: 100%; height: 140px; }
}

/* Publication list */
.pub-list {
  padding-left: 1.5rem;
  line-height: 1.65;
}
.pub-list li {
  margin-bottom: 0.75rem;
  padding-left: 0.25rem;
}