:root {
  --brand-dark: #071827;
  --brand-mid: #0f2740;
  --brand-light: #2c4d73;
  --accent: #00b0ff;
  --accent-soft: rgba(0, 176, 255, 0.15);
  --bg-body: #f5f7fb;
  --card-bg: #ffffff;
  --text-main: #1f2933;
  --text-muted: #6b7280;
  --border: #e2e8f0;
}

body {
  margin: 0;
  font-family: system-ui, -apple-system, BlinkMacSystemFont, "Segoe UI", sans-serif;
  background: var(--bg-body);
  color: var(--text-main);
}

.top-nav {
  background: #ffffff;
  border-bottom: 1px solid var(--border);
  padding: 0.75rem 1.5rem;
  display: flex;
  align-items: center;
  justify-content: space-between;
  position: sticky;
  top: 0;
  z-index: 20;
}

.brand {
  display: flex;
  flex-direction: column;
  gap: 0.15rem;
}

.brand-title {
  font-weight: 700;
  font-size: 1.2rem;
  text-transform: uppercase;
  letter-spacing: 0.12em;
  color: var(--brand-dark);
}
.brand-title span { color: var(--accent); }

.brand-sub {
  font-size: 0.72rem;
  text-transform: uppercase;
  letter-spacing: 0.18em;
  color: var(--text-muted);
}

.nav-links {
  display: flex;
  gap: 1.5rem;
  color: var(--text-muted);
  font-size: 0.92rem;
}

.nav-links a {
  text-decoration: none;
  color: inherit;
  padding-bottom: 0.15rem;
  position: relative;
}

.nav-links a:hover::after {
  content: "";
  position: absolute;
  left: 0;
  right: 0;
  bottom: 0;
  height: 2px;
  background: var(--accent);
}

main {
  max-width: 1800px;
  margin: 2.5rem auto 2rem;
  padding: 0 1.5rem;
  animation: fadeSlideIn 0.45s ease-out;
}

@keyframes fadeSlideIn {
  from { opacity: 0; transform: translateY(10px); }
  to   { opacity: 1; transform: translateY(0); }
}

.collab-grid {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: 1.8rem;
}

.card {
  background: var(--card-bg);
  border-radius: 1rem;
  border: 1px solid var(--border);
  padding: 2rem 2rem;
  text-align: center;
  box-shadow: 0 10px 30px rgba(15, 23, 42, 0.06);
  transition: 0.2s ease-out;
}

.card:hover {
  transform: translateY(-4px);
  box-shadow: 0 14px 32px rgba(15, 23, 42, 0.14);
}

.profile-img {
  width: 300px;
  height: 300px;
  object-fit: cover;
  border-radius: 1.2rem;
  border: 1px solid var(--border);
  box-shadow: 0 8px 22px rgba(15, 23, 42, 0.12);
  margin-bottom: 1.2rem;
  transition: 0.2s ease-out;
  image-rendering: -webkit-optimize-contrast;
}

.card:hover .profile-img {
  transform: scale(1.02);
  box-shadow: 0 12px 30px rgba(15, 23, 42, 0.18);
}

.name {
  font-size: 1.35rem;
  font-weight: 600;
  color: var(--brand-dark);
  margin-bottom: 0.3rem;
}

.role {
  font-size: 0.95rem;
  color: var(--text-muted);
  margin-bottom: 1rem;
}

.badge-row {
  display: flex;
  gap: 0.45rem;
  flex-wrap: wrap;
  justify-content: center;
  margin-bottom: 1.2rem;
}

.badge {
  padding: 0.25rem 0.65rem;
  border-radius: 999px;
  border: 1px solid rgba(148, 163, 184, 0.8);
  font-size: 0.7rem;
  text-transform: uppercase;
  letter-spacing: 0.12em;
  background: #fff;
  transition: 0.15s;
}

.badge:hover {
  background: var(--accent-soft);
  transform: translateY(-1px);
  border-color: var(--accent);
}

.summary {
  font-size: 0.92rem;
  line-height: 1.58;
  color: var(--text-main);
  margin-bottom: 1.1rem;
}

.social-links {
  display: flex;
  gap: 0.7rem;
  justify-content: center;
  flex-wrap: wrap;
}

.social-links a {
  padding: 0.35rem 0.75rem;
  border-radius: 999px;
  border: 1px solid rgba(148, 163, 184, 0.8);
  text-decoration: none;
  color: var(--brand-mid);
  background: #fff;
  font-size: 0.78rem;
  transition: 0.15s;
}

.social-links a:hover {
  background: linear-gradient(135deg, #e0f2fe, #f5f7fb);
  border-color: var(--accent);
  box-shadow: 0 8px 20px rgba(56, 189, 248, 0.35);
  transform: translateY(-1px);
}

.footer-note {
  max-width: 900px;
  margin: 2.5rem auto 0;
  text-align: center;
  font-size: 0.95rem;
  color: var(--text-muted);
  line-height: 1.6;
}

@media (max-width: 900px) {
  .collab-grid { grid-template-columns: 1fr; }
  .profile-img { width: 280px; height: 280px; }
  main { margin-top: 1.5rem; }
}

/* ── Mobile navigation ──────────────────────────────────── */
.nav-hamburger {
  display: none;
  flex-direction: column;
  gap: 5px;
  background: none;
  border: none;
  cursor: pointer;
  padding: 4px;
  border-radius: 6px;
}
.nav-hamburger span {
  display: block;
  width: 22px;
  height: 2px;
  background: var(--text-muted);
  border-radius: 2px;
  transition: background 0.15s;
}
.nav-hamburger:hover span { background: var(--brand-dark); }

@media (max-width: 640px) {
  .nav-hamburger {
    display: flex;
  }

  .nav-links {
    display: none;
    position: absolute;
    top: 100%;
    left: 0;
    right: 0;
    background: #fff;
    border-bottom: 1px solid #e5e7eb;
    flex-direction: column;
    gap: 0;
    padding: 0.5rem 0;
    z-index: 100;
    box-shadow: 0 4px 12px rgba(15,23,42,0.08);
  }

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

  .nav-links a {
    padding: 0.75rem 1.5rem;
    font-size: 0.95rem;
    border-bottom: 1px solid #f1f5f9;
  }

  .nav-links a:last-child { border-bottom: none; }

  .top-nav {
    position: relative;
  }

  .profile-img {
    width: 220px;
    height: 220px;
  }

  .card {
    padding: 1.5rem 1.25rem;
  }
}