/* ==========================================================================
   DESIGN TOKENS
   To retheme the entire site, edit only the values in :root below.
   Every color in the stylesheet is consumed via these semantic variables.
   ========================================================================== */
:root {
  /* --- Backgrounds --- */
  --bg-default:       #ffffff;
  --bg-subtle:        #f2faf6;     /* light tint of accent, used for alt sections */
  --bg-inverse:       #0c2118;     /* dark, used for footer */

  /* --- Text --- */
  --text-primary:     #1a2e22;     /* near-black, main body text */
  --text-secondary:   #4a6356;     /* mid-tone, secondary body text */
  --text-muted:       #7a9489;     /* subdued labels, metadata */
  --text-inverse:     rgba(236,252,244,0.92); /* text on dark/inverse backgrounds */

  /* --- Borders --- */
  --border-default:   rgba(26,158,106,0.18); /* accent-tinted, for cards & focus rings */
  --border-subtle:    rgba(0,0,0,0.07);       /* near-neutral, low-contrast dividers */

  /* --- Accent (primary brand color) --- */
  --accent:           #1a9e6a;
  --accent-hover:     #148455;
  --accent-active:    #0e6b43;
  --accent-fg:        #ffffff;          /* foreground on top of --accent */
  --accent-subtle:    rgba(26,158,106,0.09);  /* very faint tint, badge backgrounds */
  --accent-muted:     rgba(26,158,106,0.18);  /* slightly stronger, hover borders */

  /* --- Semantic states --- */
  --success:          #16a34a;
  --warning:          #d97706;
  --danger:           #dc2626;

  /* --- Shadows (neutral, not color-specific) --- */
  --shadow-sm:   0 2px 10px rgba(10,40,25,0.07);
  --shadow-md:   0 8px 28px  rgba(10,40,25,0.11);
  --shadow-lg:   0 20px 48px -14px rgba(10,40,25,0.2);

  /* --- Radii --- */
  --radius-sm:   0.5rem;
  --radius-md:   0.9rem;
  --radius-lg:   1.3rem;

  /* --- Motion --- */
  --transition:  0.22s ease;
}

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

html { scroll-behavior: smooth; }

body {
  font-family: 'Inter', system-ui, sans-serif;
  font-size: 16px;
  line-height: 1.7;
  color: var(--text-primary);
  background: var(--bg-default);
}

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

ul { list-style: none; }

.container {
  max-width: 1100px;
  margin: 0 auto;
  padding: 0 1.5rem;
}

/* ==========================================================================
   NAVBAR
   ========================================================================== */
#navbar {
  position: fixed;
  top: 0; left: 0; right: 0;
  z-index: 100;
  background: rgba(255,255,255,0.97);
  backdrop-filter: blur(12px);
  -webkit-backdrop-filter: blur(12px);
  border-top: 4px solid var(--accent);
  border-bottom: 1px solid var(--border-subtle);
  box-shadow: var(--shadow-sm);
  transition: box-shadow var(--transition);
}

.nav-inner {
  max-width: 1100px;
  margin: 0 auto;
  padding: 0 1.5rem;
  height: 60px;
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 1rem;
}

.nav-brand {
  display: flex;
  align-items: center;
  gap: 0.5rem;
  font-weight: 700;
  font-size: 1.1rem;
  color: var(--text-primary);
  white-space: nowrap;
}
.nav-brand:hover { color: var(--accent); }
.nav-logo-icon { color: var(--accent); font-size: 1.15rem; }

.nav-links {
  display: flex;
  align-items: center;
  gap: 0.15rem;
  flex-wrap: nowrap;
}
.nav-links li a {
  display: block;
  padding: 0.4rem 0.8rem;
  border-radius: var(--radius-sm);
  font-size: 0.9rem;
  font-weight: 500;
  color: var(--text-secondary);
  transition: background var(--transition), color var(--transition);
}
.nav-links li a:hover {
  background: var(--accent-subtle);
  color: var(--accent);
}
.nav-links li a.active {
  background: var(--accent-subtle);
  color: var(--accent);
}
.nav-links .nav-cta {
  background: var(--accent);
  color: var(--accent-fg) !important;
  padding: 0.4rem 1rem;
  font-weight: 600;
  display: inline-flex;
  align-items: center;
  gap: 0.35rem;
}
.nav-links .nav-cta:hover {
  background: var(--accent-hover);
  color: var(--accent-fg) !important;
}
.nav-ext-icon { font-size: 0.7em; opacity: 0.8; }

.nav-burger {
  display: none;
  flex-direction: column;
  gap: 5px;
  background: none;
  border: none;
  cursor: pointer;
  padding: 0.35rem;
}
.nav-burger span {
  display: block;
  width: 24px; height: 2px;
  background: var(--text-primary);
  border-radius: 2px;
  transition: transform var(--transition), opacity var(--transition);
}

/* ==========================================================================
   SECTION BASE
   ========================================================================== */
.section { padding: 5rem 0; }
.section-default { background: var(--bg-default); }
.section-subtle  { background: var(--bg-subtle); }

.section-header {
  text-align: center;
  margin-bottom: 3rem;
}
.section-heading {
  font-family: 'Playfair Display', Georgia, serif;
  font-size: clamp(1.8rem, 3.5vw, 2.35rem);
  font-weight: 700;
  color: var(--text-primary);
  position: relative;
  display: inline-block;
  padding-bottom: 0.75rem;
}
.section-heading::after {
  content: '';
  position: absolute;
  bottom: 0; left: 50%; transform: translateX(-50%);
  width: 2.75rem; height: 3px;
  border-radius: 2px;
  background: var(--accent);
}
.section-sub {
  margin-top: 1rem;
  color: var(--text-secondary);
  font-size: 1rem;
}

/* ==========================================================================
   BUTTONS
   ========================================================================== */
.btn {
  display: inline-flex;
  align-items: center;
  gap: 0.5rem;
  padding: 0.65rem 1.35rem;
  border-radius: var(--radius-sm);
  font-weight: 600;
  font-size: 0.92rem;
  cursor: pointer;
  transition: transform var(--transition), box-shadow var(--transition), background var(--transition);
}
.btn-primary {
  background: var(--accent);
  color: var(--accent-fg);
  box-shadow: 0 6px 20px -8px color-mix(in srgb, var(--accent) 55%, transparent);
}
.btn-primary:hover {
  background: var(--accent-hover);
  color: var(--accent-fg);
  transform: translateY(-2px);
  box-shadow: 0 10px 24px -8px color-mix(in srgb, var(--accent) 50%, transparent);
}
.btn-outline {
  background: var(--bg-default);
  color: var(--accent);
  border: 1.5px solid var(--accent-muted);
}
.btn-outline:hover {
  transform: translateY(-2px);
  border-color: var(--accent);
  color: var(--accent-hover);
  box-shadow: var(--shadow-sm);
}

/* ==========================================================================
   HERO / ABOUT
   ========================================================================== */
.hero-section {
  position: relative;
  padding: 8rem 0 5.5rem;
  overflow: hidden;
  background: linear-gradient(150deg,
    color-mix(in srgb, var(--accent) 5%, var(--bg-default)) 0%,
    var(--bg-default) 55%,
    var(--bg-subtle) 100%
  );
}
.hero-deco {
  position: absolute;
  border-radius: 50%;
  pointer-events: none;
}
.hero-deco-1 {
  width: 520px; height: 520px;
  top: -160px; right: -130px;
  background: radial-gradient(circle,
    color-mix(in srgb, var(--accent) 14%, transparent) 0%,
    transparent 65%
  );
}
.hero-deco-2 {
  width: 400px; height: 400px;
  bottom: -120px; left: -100px;
  background: radial-gradient(circle,
    color-mix(in srgb, var(--accent) 9%, transparent) 0%,
    transparent 65%
  );
}

.hero-content {
  display: flex;
  align-items: center;
  gap: 3.5rem;
  position: relative;
  z-index: 1;
}
.hero-text  { flex: 1 1 0; }
.hero-visual { flex: 0 0 auto; }

.hero-badge {
  display: inline-block;
  background: var(--accent-subtle);
  color: var(--accent-hover);
  font-size: 0.77rem;
  font-weight: 700;
  letter-spacing: 0.06em;
  text-transform: uppercase;
  padding: 0.28rem 0.85rem;
  border-radius: 999px;
  margin-bottom: 1rem;
  border: 1px solid var(--accent-muted);
  transition: background var(--transition), border-color var(--transition);
}
a.hero-badge:hover {
  background: var(--accent-muted);
  border-color: var(--accent);
  color: var(--accent-active);
}

.hero-affiliations {
  display: flex;
  align-items: center;
  gap: 1.25rem;
  margin-top: 2rem;
  flex-wrap: wrap;
}
.affil-logo {
  display: inline-flex;
  align-items: center;
  opacity: 0.82;
  transition: opacity var(--transition), transform var(--transition);
}
.affil-logo:hover {
  opacity: 1;
  transform: translateY(-1px);
}
.affil-logo img {
  width: auto;
  display: block;
  object-fit: contain;
}
/* ATHENE logo has little inner whitespace — keep it compact */
.affil-logo .logo-athene {
  height: 42px;
}
/* TU Darmstadt SVG has ~25% whitespace margin baked into its viewBox,
   so we render it taller so the visible content matches ATHENE's size */
.affil-logo .logo-tuda {
  height: 68px;
}
.affil-sep {
  display: inline-block;
  width: 1px;
  height: 32px;
  background: var(--border-subtle);
  flex-shrink: 0;
}

.hero-title {
  font-family: 'Playfair Display', Georgia, serif;
  font-size: clamp(2.6rem, 5.5vw, 3.8rem);
  font-weight: 700;
  line-height: 1.15;
  color: var(--text-primary);
  margin-bottom: 0.4rem;
  letter-spacing: -0.02em;
}
.hero-title .accent { color: var(--accent); }

.hero-subtitle {
  font-size: clamp(1rem, 2vw, 1.15rem);
  font-weight: 500;
  color: var(--text-secondary);
  margin-bottom: 1.1rem;
}
.hero-desc {
  color: var(--text-secondary);
  font-size: 0.96rem;
  line-height: 1.75;
  margin-bottom: 0.8rem;
}
.hero-links {
  display: flex;
  gap: 0.85rem;
  flex-wrap: wrap;
  margin-top: 1.75rem;
}

/* hero visual card stack */
.hero-card-stack {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: 1rem;
  width: 250px;
}
.hero-stat-card {
  background: var(--bg-default);
  border: 1px solid var(--border-default);
  border-radius: var(--radius-md);
  padding: 1.2rem 1rem;
  text-align: center;
  box-shadow: var(--shadow-sm);
  transition: transform var(--transition), box-shadow var(--transition);
}
.hero-stat-card:hover {
  transform: translateY(-3px);
  box-shadow: var(--shadow-md);
}
.hero-stat-icon {
  font-size: 1.4rem;
  color: var(--accent);
  margin-bottom: 0.45rem;
}
.hero-stat-label {
  font-size: 0.75rem;
  font-weight: 600;
  color: var(--text-primary);
  line-height: 1.3;
}

/* ==========================================================================
   NEWS
   ========================================================================== */
.news-list {
  display: flex;
  flex-direction: column;
  border-left: 3px solid var(--accent-muted);
  padding-left: 1.5rem;
  margin-left: 0.5rem;
}
.news-item {
  display: flex;
  gap: 1.25rem;
  padding: 1.25rem 0;
  border-bottom: 1px solid var(--border-subtle);
  position: relative;
}
.news-item::before {
  content: '';
  position: absolute;
  left: -1.6rem; top: 1.55rem;
  width: 10px; height: 10px;
  border-radius: 50%;
  background: var(--accent);
  border: 2px solid var(--bg-subtle);
}
.news-item:last-child { border-bottom: none; }
.news-actions {
  margin-top: 1.25rem;
  display: flex;
  justify-content: center;
}

.news-date {
  flex: 0 0 72px;
  font-size: 0.78rem;
  font-weight: 700;
  color: var(--accent);
  letter-spacing: 0.04em;
  text-transform: uppercase;
  padding-top: 0.1rem;
  white-space: nowrap;
}
.news-body p { color: var(--text-secondary); font-size: 0.94rem; line-height: 1.65; }
.news-body strong { color: var(--text-primary); }

/* ==========================================================================
   RESEARCH
   ========================================================================== */
.research-grid {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(240px, 1fr));
  gap: 1.4rem;
}
.research-card {
  background: var(--bg-default);
  border: 1px solid var(--border-subtle);
  border-radius: var(--radius-lg);
  padding: 1.9rem 1.6rem;
  box-shadow: var(--shadow-sm);
  transition: transform var(--transition), box-shadow var(--transition), border-color var(--transition);
  display: flex;
  flex-direction: column;
  gap: 0.7rem;
}
.research-card:hover {
  transform: translateY(-4px);
  box-shadow: var(--shadow-lg);
  border-color: var(--border-default);
}
.research-icon {
  width: 46px; height: 46px;
  border-radius: var(--radius-sm);
  background: var(--accent-subtle);
  display: flex;
  align-items: center;
  justify-content: center;
  font-size: 1.2rem;
  color: var(--accent);
  margin-bottom: 0.2rem;
}
.research-card h3 {
  font-size: 1.05rem;
  font-weight: 700;
  color: var(--text-primary);
  line-height: 1.3;
}
.research-card p {
  font-size: 0.92rem;
  color: var(--text-secondary);
  line-height: 1.7;
  flex: 1;
}
.research-tags {
  display: flex;
  flex-wrap: wrap;
  gap: 0.4rem;
  margin-top: 0.4rem;
}
.research-tags li {
  font-size: 0.73rem;
  font-weight: 600;
  letter-spacing: 0.02em;
  color: var(--accent-hover);
  background: var(--accent-subtle);
  border: 1px solid var(--accent-muted);
  border-radius: 999px;
  padding: 0.18rem 0.6rem;
}

/* ==========================================================================
   PRODUCTS
   ========================================================================== */
.products-grid {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(280px, 1fr));
  gap: 1.5rem;
}
.product-card {
  background: var(--bg-default);
  border: 1px solid var(--border-subtle);
  border-radius: var(--radius-lg);
  padding: 2rem 1.75rem;
  box-shadow: var(--shadow-sm);
  transition: transform var(--transition), box-shadow var(--transition), border-color var(--transition);
  display: flex;
  flex-direction: column;
  gap: 0.8rem;
}
.product-card:hover {
  transform: translateY(-4px);
  box-shadow: var(--shadow-lg);
  border-color: var(--border-default);
}
.product-icon {
  width: 52px; height: 52px;
  border-radius: var(--radius-md);
  background: var(--accent);
  display: flex;
  align-items: center;
  justify-content: center;
  font-size: 1.35rem;
  color: var(--accent-fg);
  margin-bottom: 0.3rem;
}
.product-label {
  font-size: 0.72rem;
  font-weight: 700;
  letter-spacing: 0.07em;
  text-transform: uppercase;
  color: var(--accent);
  margin-bottom: -0.2rem;
}
.product-card h3 {
  font-size: 1.15rem;
  font-weight: 700;
  color: var(--text-primary);
}
.product-card p {
  font-size: 0.93rem;
  color: var(--text-secondary);
  line-height: 1.7;
  flex: 1;
}
.product-actions {
  display: flex;
  gap: 0.75rem;
  flex-wrap: wrap;
  margin-top: 0.5rem;
}
.product-actions .btn { font-size: 0.85rem; padding: 0.5rem 1.1rem; }

/* ==========================================================================
   PUBLICATIONS
   ========================================================================== */
.pub-list {
  display: flex;
  flex-direction: column;
  gap: 1.2rem;
}
.pub-card {
  background: var(--bg-default);
  border: 1px solid var(--border-subtle);
  border-left: 4px solid var(--accent);
  border-radius: var(--radius-md);
  padding: 1.65rem 1.85rem;
  box-shadow: var(--shadow-sm);
  transition: transform var(--transition), box-shadow var(--transition);
}
.pub-card:hover {
  transform: translateY(-3px);
  box-shadow: var(--shadow-md);
}
.pub-meta {
  display: flex;
  gap: 0.5rem;
  margin-bottom: 0.7rem;
  flex-wrap: wrap;
}
.pub-badge {
  font-size: 0.71rem;
  font-weight: 700;
  letter-spacing: 0.06em;
  text-transform: uppercase;
  padding: 0.18rem 0.6rem;
  border-radius: 999px;
}
.pub-badge-year { background: var(--accent-subtle); color: var(--accent-hover); }
.pub-badge-proc { background: rgba(93,107,137,0.1); color: #4a5568; }

.pub-title {
  font-size: 1.06rem;
  font-weight: 700;
  color: var(--text-primary);
  line-height: 1.4;
  margin-bottom: 0.3rem;
}
.pub-authors {
  font-size: 0.87rem;
  color: var(--accent);
  font-weight: 500;
  margin-bottom: 0.1rem;
}
.pub-venue {
  font-size: 0.81rem;
  color: var(--text-muted);
  margin-bottom: 0.6rem;
}
.pub-abstract {
  font-size: 0.91rem;
  color: var(--text-secondary);
  line-height: 1.65;
  margin-bottom: 0.7rem;
}
.pub-topics {
  display: flex;
  flex-wrap: wrap;
  gap: 0.4rem;
}
.pub-topic {
  font-size: 0.73rem;
  font-weight: 500;
  color: var(--text-secondary);
  background: var(--bg-subtle);
  border-radius: 999px;
  padding: 0.16rem 0.58rem;
}
.pub-actions {
  margin-top: 1.25rem;
  display: flex;
  justify-content: center;
}

/* ==========================================================================
   TEAM
   ========================================================================== */
.team-grid {
  display: flex;
  flex-direction: column;
  gap: 1.2rem;
}
.team-card {
  display: flex;
  align-items: flex-start;
  gap: 1.5rem;
  background: var(--bg-default);
  border: 1px solid var(--border-subtle);
  border-radius: var(--radius-lg);
  padding: 1.65rem 1.85rem;
  box-shadow: var(--shadow-sm);
  color: var(--text-primary);
  transition: transform var(--transition), box-shadow var(--transition), border-color var(--transition);
  text-decoration: none;
}
.team-card:hover {
  transform: translateY(-3px);
  box-shadow: var(--shadow-md);
  border-color: var(--border-default);
  color: var(--text-primary);
}
.team-card:hover .team-link-icon {
  transform: translateX(4px);
  color: var(--accent);
}

.team-avatar {
  flex: 0 0 80px;
  width: 80px; height: 80px;
  border-radius: 50%;
  overflow: hidden;
  border: 2px solid var(--border-default);
  flex-shrink: 0;
  background: var(--bg-subtle);
}
.team-avatar img {
  width: 100%; height: 100%;
  object-fit: cover;
  object-position: center top;
  display: block;
}

.team-info { flex: 1; }
.team-name {
  font-size: 1.08rem;
  font-weight: 700;
  color: var(--text-primary);
  margin-bottom: 0.15rem;
}
.team-role {
  font-size: 0.75rem;
  font-weight: 700;
  letter-spacing: 0.07em;
  text-transform: uppercase;
  color: var(--accent);
  margin-bottom: 0.18rem;
}
.team-affiliation {
  font-size: 0.84rem;
  color: var(--text-muted);
  margin-bottom: 0.5rem;
}
.team-focus {
  font-size: 0.91rem;
  color: var(--text-secondary);
  line-height: 1.6;
}
.team-link-icon {
  flex: 0 0 auto;
  color: var(--text-muted);
  font-size: 0.88rem;
  transition: transform var(--transition), color var(--transition);
  padding-top: 0.3rem;
}

/* ==========================================================================
   FOOTER
   ========================================================================== */
.site-footer {
  position: relative;
  overflow: hidden;
  background: var(--bg-inverse);
  padding: 3.5rem 0 2.5rem;
  text-align: center;
}
.footer-deco {
  position: absolute;
  border-radius: 50%;
  pointer-events: none;
}
.footer-deco-1 {
  width: 360px; height: 360px;
  top: -140px; right: -80px;
  background: radial-gradient(circle,
    color-mix(in srgb, var(--accent) 22%, transparent) 0%,
    transparent 65%
  );
}
.footer-deco-2 {
  width: 300px; height: 300px;
  bottom: -100px; left: -60px;
  background: radial-gradient(circle,
    color-mix(in srgb, var(--accent) 12%, transparent) 0%,
    transparent 65%
  );
}
.footer-inner {
  position: relative; z-index: 1;
  display: flex;
  flex-direction: column;
  align-items: center;
  gap: 0.7rem;
}
.footer-brand {
  display: flex;
  align-items: center;
  gap: 0.5rem;
  font-weight: 700;
  font-size: 1.2rem;
  color: var(--text-inverse);
}
.footer-logo-icon { color: var(--accent); }
.footer-tagline {
  font-size: 0.87rem;
  color: color-mix(in srgb, var(--text-inverse) 55%, transparent);
}
.footer-links {
  display: flex;
  align-items: center;
  gap: 1.25rem;
  margin: 0.4rem 0;
}
.footer-links a {
  color: color-mix(in srgb, var(--text-inverse) 65%, transparent);
  font-size: 1rem;
  font-weight: 500;
  transition: color var(--transition);
}
.footer-links a:hover { color: var(--accent); }
.footer-divider {
  display: inline-block;
  width: 1px; height: 1rem;
  background: color-mix(in srgb, var(--text-inverse) 20%, transparent);
  vertical-align: middle;
}
.footer-copy {
  font-size: 0.79rem;
  color: color-mix(in srgb, var(--text-inverse) 35%, transparent);
  margin-top: 0.2rem;
}

/* ==========================================================================
   RESPONSIVE
   ========================================================================== */
@media (max-width: 820px) {
  .hero-content { flex-direction: column; text-align: center; gap: 2.5rem; }
  .hero-links { justify-content: center; }
  .hero-affiliations { justify-content: center; }
  .hero-visual { width: 100%; display: flex; justify-content: center; }
  .hero-card-stack { width: 280px; }
  .research-grid, .products-grid { grid-template-columns: 1fr; }
}

@media (max-width: 640px) {
  .nav-links {
    display: none;
    position: absolute;
    top: 64px; left: 0; right: 0;
    background: rgba(255,255,255,0.99);
    border-bottom: 1px solid var(--border-subtle);
    flex-direction: column;
    padding: 0.75rem 0 1rem;
    gap: 0;
    box-shadow: var(--shadow-md);
  }
  .nav-links.open { display: flex; }
  .nav-links li a { padding: 0.65rem 1.5rem; border-radius: 0; }
  .nav-links .nav-cta { margin: 0.25rem 1.25rem; border-radius: var(--radius-sm); text-align: center; }
  .nav-burger { display: flex; }

  .team-card { flex-direction: column; gap: 1rem; }
  .team-link-icon { display: none; }
  .news-item { flex-direction: column; gap: 0.35rem; }
  .news-date { flex: none; }
  .pub-card { padding: 1.2rem 1.2rem; }
  .section { padding: 3.5rem 0; }
  .hero-section { padding: 6rem 0 3.5rem; }
}