:root {
  --primary: #0b7285;
  --accent: #ffb703;
  --bg: #f5f7fb;
  --card-bg: #ffffff;
  --text: #123047;
}

body {
  font-family: system-ui, sans-serif;
  background: var(--bg);
  color: var(--text);
  margin: 0;
  line-height: 1.6;
}

/* --- Sticky Top Navigation Bar --- */
.top-nav {
  position: sticky;
  top: 0;
  z-index: 1000;
  background: #0b7285;
  padding: 0.75rem 1rem;
  display: flex;
  justify-content: space-between;
  align-items: center;
}

.top-nav-links {
  display: flex;
  gap: 1.5rem;
}

.top-nav a {
  color: #fff;
  text-decoration: none;
  font-weight: 600;
  font-size: 0.95rem;
  display: flex;
  align-items: center;
  gap: 0.35rem;
}

.top-nav a:hover {
  text-decoration: underline;
}

/* Icons */
.nav-icon {
  width: 18px;
  height: 18px;
  display: inline-block;
}

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

.hamburger div {
  width: 25px;
  height: 3px;
  background: white;
  border-radius: 2px;
}

/* Mobile Menu */
.mobile-menu {
  display: none;
  flex-direction: column;
  background: #0b7285;
  padding: 1rem;
}

.mobile-menu a {
  color: #fff;
  padding: 0.5rem 0;
  text-decoration: none;
  font-weight: 600;
  display: flex;
  align-items: center;
  gap: 0.35rem;
}

/* Responsive */
@media (max-width: 800px) {
  .top-nav-links {
    display: none;
  }

  .hamburger {
    display: flex;
  }
}

header {
  background: linear-gradient(135deg, #0b7285, #1864ab);
  color: #fff;
  padding: 2rem 1rem;
  text-align: center;
}

main {
  max-width: 900px;
  margin: 2rem auto;
  padding: 0 1rem;
}

.activity-grid {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(250px, 1fr));
  gap: 1rem;
}

.activity-card {
  background: var(--card-bg);
  padding: 1rem;
  border-radius: 0.75rem;
  box-shadow: 0 4px 10px rgba(0,0,0,0.08);
}

.activity-card h3 {
  color: var(--primary);
  margin-top: 0;
}

footer {
  text-align: center;
  padding: 1rem;
  margin-top: 2rem;
  background: #f8fafc;
  color: #6b7280;
  font-size: 0.85rem;
}