body {
  font-family: 'Segoe UI', sans-serif;
  margin: 0;
  background: #f3f7fa;
  color: #222;
  display: flex;
  justify-content: center;
  align-items: center;
  min-height: 100vh;
}

.library-container {
  text-align: center;
  padding: 40px 20px;
  max-width: 900px;
  background: #fff;
  border-radius: 16px;
  box-shadow: 0 6px 16px rgba(0, 0, 0, 0.1);
}

header h1 {
  color: #0066cc;
  margin-bottom: 8px;
}

.tagline {
  color: #666;
  font-size: 1rem;
  margin-bottom: 30px;
}

.tiles {
  display: flex;
  flex-wrap: wrap;
  justify-content: center;
  gap: 20px;
  margin-bottom: 30px;
}

.tile {
  display: block;
  width: 260px;
  padding: 25px;
  border-radius: 12px;
  text-decoration: none;
  color: #fff;
  transition: 0.3s ease;
  box-shadow: 0 4px 12px rgba(0, 0, 0, 0.15);
}

.tile h2 {
  margin: 0 0 8px;
}

.tile p {
  margin: 0;
  font-size: 0.9rem;
}

.tile.student { background: #0078d7; }
.tile.teacher { background: #28a745; }
.tile.admin { background: #ff9800; }

.tile:hover {
  transform: scale(1.05);
  box-shadow: 0 6px 20px rgba(0, 0, 0, 0.2);
}

footer {
  font-size: 0.9rem;
  color: #555;
}

.welcome {
  margin-bottom: 25px;
  font-size: 1rem;
  color: #333;
}

@media (max-width: 700px) {
  .tile {
    width: 100%;
    max-width: 300px;
    display: block;
  }
  header {
    position: fixed;
    top: 0;
    padding: 20px;
  }
  header h1 {
    text-align: left;
    font-size: 1.5rem;
  }
}