body {
  background-color: #f4f6f8;
}

.book-card {
  border-radius: 10px;
  box-shadow: 0 2px 8px rgba(0,0,0,0.1);
}

.book-card img {
  height: 200px;
  object-fit: cover;
}

.accordion-button {
  background-color: #343a40;
  color: white;
}

.accordion-button:not(.collapsed) {
  background-color: #0d6efd;
  color: white;
}

.footer {
  position: fixed;
  bottom: 0;
  width: 100%;
}

.sidebar ul {
  padding-left: 0;
  margin-bottom: 0;
}

.sidebar ul li {
  margin-bottom: .5rem;
}

.sidebar ul li strong {
  display: block;
  margin-bottom: .25rem;
  color: #0d6efd;
}

.sidebar ul li ul {
  padding-left: 1rem;
  border-left: 2px solid #e9ecef;
  margin-top: .25rem;
}

.book-cover {
  height: 220px;
  background: #f8f9fa;
  display: flex;
  align-items: center;
  justify-content: center;
  border-bottom: 1px solid #eee;
  overflow: hidden;
}

.book-cover img {
  max-height: 100%;
  max-width: 100%;
  object-fit: contain;
}

.library-code-box {
  font-size: 1.4rem;
  font-weight: 700;
  letter-spacing: 2px;
  background: #0d6efd12;
  border: 2px dashed #0d6efd;
  border-radius: 8px;
  padding: .75rem 1rem;
  color: #0d6efd;
  display: inline-block;
}

.stat-card {
  border-radius: 12px;
  color: #fff;
  padding: 1.25rem;
}

.admin-sidebar {
  min-height: calc(100vh - 56px);
  background: #212529;
}

.admin-sidebar a {
  color: #ced4da;
  display: block;
  padding: .65rem 1rem;
  text-decoration: none;
  border-left: 3px solid transparent;
}

.admin-sidebar a:hover, .admin-sidebar a.active {
  color: #fff;
  background: #2c3136;
  border-left-color: #0d6efd;
}

.role-badge-principal { background:#dc3545; }
.role-badge-secondary { background:#fd7e14; }
.role-badge-reader { background:#6c757d; }