* {
  box-sizing: border-box;
  margin: 0;
  padding: 0;
}

body {
  font-family: system-ui, -apple-system, Segoe UI, Roboto, Arial, sans-serif;
  background: #121212; /* dark background */
  color: #e4e4e4;      /* light text */
}

.site-header {
  text-align: center;
  padding: 3rem 1rem 1.5rem;
}

.site-header h1 {
  font-size: 2.4rem;
  margin-bottom: 0.5rem;
}

.subtitle {
  color: #b0b0b0;
  font-size: 1.1rem;
}

.wrapper {
  max-width: 1050px;
  margin: 0 auto;
  padding: 1.5rem;
}

.grid {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(230px, 1fr));
  gap: 1.25rem;
}

.card {
  display: block;
  background: #1e1e1e; /* dark card */
  color: #e4e4e4;
  padding: 1.5rem;
  border-radius: 16px;
  text-decoration: none;
  border: 1px solid #2c2c2c;
  box-shadow: 0 8px 20px rgba(0,0,0,0.5);
  transition: transform 0.15s ease, box-shadow 0.15s ease;

  display: flex;
  flex-direction: column;
  gap: 0.75rem;
}

.card:hover {
  transform: translateY(-4px);
  box-shadow: 0 14px 28px rgba(0,0,0,0.7);
}

.card h2 {
  font-size: 1.4rem;
  margin-bottom: 0.5rem;
}

.card p {
  color: #b0b0b0;
  line-height: 1.4;
}

.site-footer {
  text-align: center;
  padding: 2rem 1rem;
  color: #888;
}

/* Assignment buttons */
.btn {
  display: block;
  text-align: center;
  padding: 0.6rem;
  border-radius: 10px;
  background: #2f6fa3; /* keep your blue */
  color: white;
  text-decoration: none;
  font-size: 0.95rem;
  transition: background 0.15s ease, transform 0.15s ease;
}

.btn:hover {
  background: #245a85;
  transform: translateY(-2px);
}