/* Lưới layout 4 cột */
.group-selection {
  display: grid;
  grid-template-columns: repeat(5, 1fr);
  gap: 24px;
  padding: 30px 10px;
  justify-items: center;
}

/* Thẻ nhóm manga */
.group-card {
  width: 220px;
  height: 330px;
  border-radius: 12px;
  text-align: center;
  text-decoration: none;
  color: black;
  font-weight: bold;
  font-size: 1.2em;
  box-shadow: 0 6px 18px rgba(0, 0, 0, 0.5);
  transition: transform 0.2s ease, box-shadow 0.2s ease;
  position: relative;
  overflow: hidden;
  display: flex;
  align-items: center;
  justify-content: center;
}

/* Ảnh nền cho mỗi thẻ */
.card-image {
  position: absolute;
  top: 0; left: 0;
  width: 100%;
  height: 100%;
  object-fit: cover;
  filter: brightness(0.5);
  z-index: 0;
  transition: filter 0.3s;
  border-radius: 12px;
}

/* Hover effect */
.group-card:hover .card-image {
  filter: brightness(0.7);
}

.group-card h2 {
  position: relative;
  z-index: 1;
  color: white;
  padding: 0 10px;
  text-shadow: 0 2px 5px rgba(0, 0, 0, 0.8);
}

/* Header logo và tiêu đề */
.centered-header {
  text-align: center;
  padding: 20px 0;
}
.centered-header .logo {
  display: block;
  margin: 0 auto 10px;
  max-width: 180px;
}

/* Footer */
.centered-footer {
  text-align: center;
  padding: 20px;
  color: #888;
  font-size: 0.9em;
}

/* Blank card (ô không click được) */
.group-card.blank {
  pointer-events: none;
}

/* Responsive */
@media (max-width: 768px) {
  .group-selection {
    grid-template-columns: repeat(2, 1fr);
  }
}
@media (max-width: 480px) {
  .group-selection {
    grid-template-columns: 1fr;
  }
}