/* NPTEL GATE departments–style study materials grid */
.materials-page {
  padding: 3rem 1rem 4rem;
  min-height: 70vh;
}

.materials-page-title {
  text-align: center;
  font-size: clamp(1.5rem, 4vw, 2rem);
  font-weight: 800;
  letter-spacing: 0.04em;
  color: var(--ac-text);
  margin-bottom: 0.5rem;
  text-transform: uppercase;
}

.materials-page-sub {
  text-align: center;
  color: var(--ac-muted);
  max-width: 42rem;
  margin: 0 auto 2.5rem;
  line-height: 1.6;
}

.materials-root {
  width: 100%;
  max-width: 100%;
  margin: 0 auto;
  padding: 0 0.5rem;
}

/* Department grid — 3 per row, full width */
.dept-grid {
  display: grid;
  grid-template-columns: repeat(3, 1fr);
  gap: 1rem 1.25rem;
  width: 100%;
}

@media (max-width: 900px) {
  .dept-grid {
    grid-template-columns: repeat(2, 1fr);
    gap: 1rem;
  }
}

@media (max-width: 520px) {
  .dept-grid {
    grid-template-columns: 1fr;
  }
}

.dept-card {
  display: flex;
  flex-direction: column;
  width: 100%;
  height: 100%;
  text-decoration: none;
  color: inherit;
  cursor: pointer;
  transition: transform 0.2s ease, box-shadow 0.2s ease;
}

.dept-card:hover,
.dept-card:focus-visible {
  transform: translateY(-4px);
  outline: none;
}

.dept-card:hover .dept-card-img,
.dept-card:focus-visible .dept-card-img {
  box-shadow: 0 8px 24px rgba(26, 77, 92, 0.2);
}

.dept-card-img {
  display: block;
  width: 100%;
  flex: 1 1 auto;
  min-height: 0;
  aspect-ratio: 4 / 3;
  object-fit: cover;
  border-radius: 8px;
  box-shadow: 0 2px 10px rgba(0, 0, 0, 0.08);
  background: #e8eef2;
}

.dept-card-label {
  display: block;
  width: 100%;
  margin-top: 0.45rem;
  padding: 0.45rem 0.5rem;
  background: #1a4a5c;
  color: #fff;
  text-align: center;
  font-size: 0.7rem;
  font-weight: 600;
  line-height: 1.25;
  border-radius: 4px;
  letter-spacing: 0.02em;
}

.dept-card-code {
  display: block;
  font-size: 0.72rem;
  font-weight: 700;
  letter-spacing: 0.04em;
}

.dept-card-name {
  display: block;
  font-size: 0.62rem;
  font-weight: 500;
  opacity: 0.92;
  margin-top: 0.15rem;
  line-height: 1.2;
}

.dept-card-count {
  display: block;
  font-size: 0.58rem;
  font-weight: 500;
  opacity: 0.8;
  margin-top: 0.15rem;
}

/* Category detail (PDF list) */
.materials-detail {
  animation: materialsFadeIn 0.25s ease;
}

@keyframes materialsFadeIn {
  from {
    opacity: 0;
    transform: translateY(8px);
  }
  to {
    opacity: 1;
    transform: translateY(0);
  }
}

.materials-back {
  display: inline-flex;
  align-items: center;
  gap: 0.35rem;
  margin-bottom: 1.25rem;
  padding: 0.5rem 0;
  background: none;
  border: none;
  color: var(--ac-primary);
  font-size: 1rem;
  font-weight: 600;
  cursor: pointer;
  font-family: inherit;
}

.materials-back:hover {
  text-decoration: underline;
}

.materials-detail-head {
  display: flex;
  flex-wrap: wrap;
  align-items: center;
  gap: 1rem;
  margin-bottom: 1.75rem;
  padding-bottom: 1rem;
  border-bottom: 2px solid var(--ac-border);
}

.materials-detail-thumb {
  width: 120px;
  height: 75px;
  object-fit: cover;
  border-radius: 8px;
  box-shadow: var(--shadow-sm);
}

.materials-detail-title {
  font-size: 1.35rem;
  font-weight: 700;
  color: var(--ac-text);
  flex: 1;
  min-width: 200px;
}

.materials-detail-meta {
  font-size: 0.9rem;
  color: var(--ac-muted);
}

.materials-pdf-grid {
  display: grid;
  grid-template-columns: repeat(auto-fill, minmax(280px, 1fr));
  gap: 1.25rem;
}

.material-pdf-card {
  background: var(--ac-surface);
  border: 1px solid var(--ac-border);
  border-radius: var(--r);
  padding: 1.25rem;
  display: flex;
  flex-direction: column;
  gap: 0.75rem;
  box-shadow: var(--shadow-sm);
  transition: border-color 0.2s, box-shadow 0.2s;
}

.material-pdf-card:hover {
  border-color: var(--ac-primary-light);
  box-shadow: var(--shadow-card);
}

.material-pdf-card h3,
.material-pdf-title {
  font-size: 0.8rem;
  font-weight: 600;
  color: var(--ac-text);
  line-height: 1.35;
  margin: 0;
  flex: 1;
  min-width: 0;
  overflow: hidden;
  display: -webkit-box;
  -webkit-line-clamp: 3;
  -webkit-box-orient: vertical;
  word-break: break-word;
}

.material-pdf-card a {
  display: inline-block;
  padding: 0.55rem 1rem;
  background: #1a4a5c;
  color: #fff;
  text-decoration: none;
  border-radius: 6px;
  text-align: center;
  font-weight: 600;
  font-size: 0.9rem;
}

.material-pdf-card a:hover {
  background: #153d4d;
}

.materials-loading,
.materials-empty {
  text-align: center;
  color: var(--ac-muted);
  padding: 2rem;
}

.materials-hidden {
  display: none !important;
}