/* Reset e configurações básicas */
* {
  margin: 0;
  padding: 0;
  box-sizing: border-box;
}

:root {
  --primary-color: #1a1a1a;
  --secondary-color: #2d2d2d;
  --accent-color: #3a3a3a;
  --text-color: #e4e4e4;
  --text-secondary: #b0b0b0;
  --border-color: #404040;
  --highlight-color: #6366f1;
  --success-color: #10b981;
  --error-color: #ef4444;
  --shadow: 0 4px 30px rgba(0, 0, 0, 0.3);
  --shadow-hover: 0 8px 40px rgba(0, 0, 0, 0.4);
  --transition: all 0.3s cubic-bezier(0.4, 0, 0.2, 1);
  --gradient: linear-gradient(135deg, var(--primary-color) 0%, var(--secondary-color) 100%);
}

body {
  font-family: 'Inter', -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, sans-serif;
  line-height: 1.6;
  color: var(--text-color);
  background: var(--primary-color);
  overflow-x: hidden;
  min-height: 100vh;
  display: flex;
  flex-direction: column;
}

/* Header */
.header {
  background: rgba(26, 26, 26, 0.95);
  backdrop-filter: blur(20px);
  border-bottom: 1px solid var(--border-color);
  padding: 1rem 0;
  position: sticky;
  top: 0;
  z-index: 100;
}

.nav {
  max-width: 1200px;
  margin: 0 auto;
  padding: 0 2rem;
  display: flex;
  justify-content: space-between;
  align-items: center;
}

.logo {
  font-size: 1.8rem;
  font-weight: 800;
  color: var(--text-color);
  text-decoration: none;
  display: flex;
  align-items: center;
  gap: 0.5rem;
  transition: var(--transition);
}

.logo-img {
  height: 40px;
  width: auto;
  filter: brightness(1.1);
  transition: var(--transition);
}

.logo:hover {
  transform: translateY(-1px);
}

.logo:hover .logo-img {
  filter: brightness(1.3);
}

.nav-links {
  display: flex;
  list-style: none;
  gap: 2rem;
}

.nav-links a {
  color: var(--text-secondary);
  text-decoration: none;
  font-weight: 500;
  transition: var(--transition);
  position: relative;
}

.nav-links a:hover {
  color: var(--text-color);
}

.nav-links a.active {
  color: var(--accent-color);
  font-weight: 600;
}

.nav-links a.active::after {
  width: 100%;
  background: var(--accent-color);
}

.nav-links a::after {
  content: '';
  position: absolute;
  bottom: -5px;
  left: 0;
  width: 0;
  height: 2px;
  background: var(--highlight-color);
  transition: var(--transition);
}

.nav-links a:hover::after {
  width: 100%;
}

/* Container principal */
.container {
  max-width: 1200px;
  margin: 0 auto;
  padding: 0 2rem;
}

/* Hero section */
.hero {
  text-align: center;
  padding: 6rem 0;
  background: var(--gradient);
  position: relative;
  overflow: hidden;
}

.hero::before {
  content: '';
  position: absolute;
  top: 0;
  left: 0;
  right: 0;
  bottom: 0;
  background: radial-gradient(circle at 30% 20%, rgba(99, 102, 241, 0.1) 0%, transparent 50%),
              radial-gradient(circle at 70% 80%, rgba(99, 102, 241, 0.05) 0%, transparent 50%);
  pointer-events: none;
}

.hero-content {
  position: relative;
  z-index: 1;
}

.hero h1 {
  font-size: 3.5rem;
  font-weight: 900;
  color: var(--text-color);
  margin-bottom: 1.5rem;
  background: linear-gradient(135deg, var(--text-color) 0%, var(--highlight-color) 100%);
  -webkit-background-clip: text;
  -webkit-text-fill-color: transparent;
  background-clip: text;
}

.hero p {
  font-size: 1.3rem;
  color: var(--text-secondary);
  max-width: 600px;
  margin: 0 auto;
}

/* Seção de livros */
.books-section {
  padding: 4rem 0;
  background: var(--primary-color);
}

.section-title {
  font-size: 2.5rem;
  font-weight: 800;
  color: var(--text-color);
  margin-bottom: 3rem;
  text-align: center;
}

/* Filtros */
.filters-container {
  display: flex;
  justify-content: center;
  gap: 1rem;
  margin-bottom: 3rem;
  flex-wrap: wrap;
}

.filter-group {
  display: flex;
  flex-direction: column;
  gap: 0.5rem;
}

.filter-label {
  font-size: 0.9rem;
  font-weight: 600;
  color: var(--text-secondary);
  text-transform: uppercase;
  letter-spacing: 0.5px;
}

.filter-select,
.filter-input {
  padding: 0.75rem 1rem;
  background: var(--secondary-color);
  border: 1px solid var(--border-color);
  border-radius: 8px;
  color: var(--text-color);
  font-size: 0.95rem;
  transition: var(--transition);
  min-width: 180px;
}

.filter-select:focus,
.filter-input:focus {
  outline: none;
  border-color: var(--highlight-color);
  box-shadow: 0 0 0 3px rgba(99, 102, 241, 0.1);
}

.filter-select option {
  background: var(--secondary-color);
  color: var(--text-color);
}

.clear-filters {
  padding: 0.75rem 1.5rem;
  background: transparent;
  border: 1px solid var(--border-color);
  border-radius: 8px;
  color: var(--text-secondary);
  cursor: pointer;
  transition: var(--transition);
  font-weight: 500;
}

.clear-filters:hover {
  border-color: var(--highlight-color);
  color: var(--highlight-color);
}

/* Grid de livros */
.books-grid {
  display: grid;
  grid-template-columns: repeat(auto-fill, minmax(320px, 1fr));
  gap: 2rem;
  margin-bottom: 3rem;
}

.book-card {
  background: var(--secondary-color);
  border-radius: 16px;
  overflow: hidden;
  box-shadow: var(--shadow);
  transition: var(--transition);
  cursor: pointer;
  border: 1px solid var(--border-color);
  position: relative;
}

.book-card::before {
  content: '';
  position: absolute;
  top: 0;
  left: 0;
  right: 0;
  bottom: 0;
  background: linear-gradient(135deg, transparent 0%, rgba(99, 102, 241, 0.03) 100%);
  opacity: 0;
  transition: var(--transition);
}

.book-card:hover {
  transform: translateY(-8px);
  box-shadow: var(--shadow-hover);
  border-color: var(--highlight-color);
}

.book-card:hover::before {
  opacity: 1;
}

.book-image {
  width: 100%;
  height: 240px;
  background: var(--accent-color);
  display: flex;
  align-items: center;
  justify-content: center;
  font-size: 4rem;
  color: var(--text-secondary);
  position: relative;
  overflow: hidden;
}

.book-image::after {
  content: '';
  position: absolute;
  top: 0;
  left: 0;
  right: 0;
  bottom: 0;
  background: linear-gradient(45deg, transparent 0%, rgba(99, 102, 241, 0.1) 100%);
  opacity: 0;
  transition: var(--transition);
}

.book-card:hover .book-image::after {
  opacity: 1;
}

.book-image img {
  width: 100%;
  height: 100%;
  object-fit: cover;
  transition: var(--transition);
}

.book-card:hover .book-image img {
  transform: scale(1.05);
}

.book-info {
  padding: 2rem;
  position: relative;
}

.book-title {
  font-size: 1.4rem;
  font-weight: 700;
  color: var(--text-color);
  margin-bottom: 0.75rem;
  line-height: 1.3;
}

.book-author {
  font-size: 1rem;
  color: var(--text-secondary);
  margin-bottom: 1rem;
  font-weight: 500;
}

.book-description {
  font-size: 0.95rem;
  color: var(--text-secondary);
  line-height: 1.6;
  margin-bottom: 1.5rem;
}

.book-category {
  display: inline-block;
  background: var(--highlight-color);
  color: white;
  padding: 0.4rem 0.9rem;
  border-radius: 20px;
  font-size: 0.8rem;
  font-weight: 600;
  text-transform: uppercase;
  letter-spacing: 0.5px;
}

/* Página individual do livro */
.book-detail {
  padding: 4rem 0;
  background: var(--primary-color);
}

.book-detail-content {
  display: grid;
  grid-template-columns: 1fr 2fr;
  gap: 4rem;
  align-items: start;
}

.book-detail-image {
  width: 100%;
  max-width: 400px;
  height: 500px;
  display: flex;
  align-items: center;
  justify-content: center;
  font-size: 5rem;
  color: var(--text-secondary);
  overflow: hidden;
  position: relative;
}

.book-detail-image img {
  width: 100%;
  height: 100%;
  object-fit: contain;
  border-radius: 12px;
  box-shadow: 0 8px 24px rgba(0, 0, 0, 0.15);
}

.book-detail-info h1 {
  font-size: 3rem;
  font-weight: 800;
  color: var(--text-color);
  margin-bottom: 1rem;
  line-height: 1.2;
}

.book-detail-info .author {
  font-size: 1.3rem;
  color: var(--text-secondary);
  margin-bottom: 2rem;
  font-weight: 600;
}

.book-detail-info .description {
  font-size: 1.1rem;
  line-height: 1.8;
  color: var(--text-secondary);
  margin-bottom: 2.5rem;
}

.book-meta {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(150px, 1fr));
  gap: 2rem;
  margin-bottom: 3rem;
  padding: 2rem;
  background: var(--secondary-color);
  border-radius: 12px;
  border: 1px solid var(--border-color);
}

.meta-item {
  display: flex;
  flex-direction: column;
  gap: 0.5rem;
}

.meta-label {
  font-size: 0.85rem;
  font-weight: 700;
  color: var(--text-secondary);
  text-transform: uppercase;
  letter-spacing: 0.5px;
}

.meta-value {
  font-size: 1.1rem;
  color: var(--text-color);
  font-weight: 600;
}

/* Botões */
.btn {
  display: inline-block;
  padding: 1rem 2rem;
  background: var(--highlight-color);
  color: white;
  text-decoration: none;
  border-radius: 10px;
  font-weight: 600;
  transition: var(--transition);
  border: none;
  cursor: pointer;
  font-size: 1rem;
  position: relative;
  overflow: hidden;
}

.btn::before {
  content: '';
  position: absolute;
  top: 0;
  left: -100%;
  width: 100%;
  height: 100%;
  background: linear-gradient(90deg, transparent, rgba(255,255,255,0.2), transparent);
  transition: var(--transition);
}

.btn:hover::before {
  left: 100%;
}

.btn:hover {
  background: #5855eb;
  transform: translateY(-2px);
  box-shadow: 0 8px 25px rgba(99, 102, 241, 0.3);
}

.btn-outline {
  background: transparent;
  color: var(--text-color);
  border: 2px solid var(--border-color);
}

.btn-outline:hover {
  background: var(--highlight-color);
  color: white;
  border-color: var(--highlight-color);
}

.btn-primary {
  background: linear-gradient(135deg, var(--highlight-color) 0%, #8b5cf6 100%);
  color: white;
  border: none;
  font-weight: 600;
  position: relative;
  overflow: hidden;
}

.btn-primary:hover {
  background: linear-gradient(135deg, #5855eb 0%, #7c3aed 100%);
  transform: translateY(-2px);
  box-shadow: 0 8px 25px rgba(99, 102, 241, 0.3);
}

.btn-primary:before {
  content: '';
  position: absolute;
  top: 0;
  left: -100%;
  width: 100%;
  height: 100%;
  background: linear-gradient(90deg, transparent, rgba(255,255,255,0.2), transparent);
  transition: left 0.5s;
}

.btn-primary:hover:before {
  left: 100%;
}

.book-actions {
  display: flex;
  gap: 1rem;
  margin-top: 2rem;
  flex-wrap: wrap;
}

.book-actions .btn {
  flex: 1;
  text-align: center;
  min-width: 150px;
}

.book-actions .no-pdf {
  color: var(--text-secondary);
  font-style: italic;
  padding: 0.75rem;
  background: rgba(255, 255, 255, 0.05);
  border: 1px solid var(--border-color);
  border-radius: 8px;
  text-align: center;
  width: 100%;
}

/* Admin styles */
.admin-container {
  max-width: 800px;
  margin: 2rem auto;
  padding: 0 2rem;
}

.admin-form {
  background: var(--secondary-color);
  padding: 2rem;
  border-radius: 12px;
  box-shadow: var(--shadow);
}

.form-group {
  margin-bottom: 1.5rem;
}

.form-label {
  display: block;
  margin-bottom: 0.5rem;
  font-weight: 500;
  color: var(--primary-color);
}

.form-input,
.form-textarea,
.form-select {
  width: 100%;
  padding: 0.75rem;
  border: 2px solid var(--border-color);
  border-radius: 6px;
  font-size: 1rem;
  transition: var(--transition);
}

.form-input:focus,
.form-textarea:focus,
.form-select:focus {
  outline: none;
  border-color: var(--primary-color);
}

.form-textarea {
  min-height: 120px;
  resize: vertical;
}

/* Main content wrapper */
.main-content {
  flex: 1;
}

/* Footer */
.footer {
  background: var(--secondary-color);
  color: var(--text-secondary);
  text-align: center;
  padding: 3rem 0;
  border-top: 1px solid var(--border-color);
  margin-top: auto;
}

.footer p {
  font-size: 0.95rem;
}

/* Responsividade */
@media (max-width: 768px) {
  .nav {
    padding: 0.5rem 1rem;
    flex-direction: row;
    justify-content: space-between;
    align-items: center;
    height: 60px;
  }
  
  .logo-img {
    height: 28px;
  }
  
  .nav-links {
    gap: 0.5rem;
    flex-wrap: nowrap;
  }
  
  .nav-links a {
    font-size: 0.9rem;
    padding: 0.5rem 0.75rem;
  }
  
  .hero {
    padding: 2rem 0;
  }
  
  .hero h1 {
    font-size: 2rem;
  }
  
  .hero p {
    font-size: 1rem;
    margin-bottom: 1.5rem;
  }
  
  .container {
    padding: 0 1rem;
  }
  
  .filters-container {
    flex-direction: column;
    align-items: center;
    gap: 1.5rem;
  }
  
  .filter-group {
    width: 100%;
    max-width: 300px;
  }
  
  .filter-select,
  .filter-input {
    width: 100%;
    min-width: auto;
  }
  
  .books-grid {
    grid-template-columns: repeat(2, 1fr);
    gap: 1rem;
  }
  
  .book-card {
    margin: 0;
    display: flex;
    flex-direction: column;
    height: 320px;
    max-width: none;
  }
  
  .book-image {
    height: 200px;
    flex-shrink: 0;
  }
  
  .book-image img {
    object-fit: cover;
    width: 100%;
    height: 100%;
  }
  
  .book-info {
    flex: 1;
    display: flex;
    flex-direction: column;
    justify-content: space-between;
    padding: 0.75rem;
  }
  
  .book-info h3 {
    font-size: 0.9rem;
    line-height: 1.3;
    margin-bottom: 0.25rem;
    display: -webkit-box;
    -webkit-line-clamp: 2;
    line-clamp: 2;
    -webkit-box-orient: vertical;
    overflow: hidden;
  }
  
  .book-info .author {
    font-size: 0.8rem;
    margin-bottom: 0.25rem;
  }
  
  .book-info .category {
    font-size: 0.75rem;
    margin-top: auto;
  }
  
  .book-detail-content {
    grid-template-columns: 1fr;
    gap: 2rem;
  }
  
  .book-detail-image {
    max-width: 100%;
    height: 350px;
    margin: 0 auto;
  }
  
  .book-detail-image img {
    object-fit: contain;
    width: 100%;
    height: 100%;
  }
  
  .book-detail-info h1 {
    font-size: 2rem;
  }
  
  .book-meta {
    grid-template-columns: 1fr;
    gap: 1rem;
  }
  
  .admin-container {
    padding: 0 1rem;
  }
  
  .admin-actions {
    flex-direction: column;
    align-items: stretch;
  }
  
  .admin-book-item {
    flex-direction: column;
    gap: 1rem;
    text-align: center;
  }
  
  .admin-book-actions {
    justify-content: center;
  }
}

@media (max-width: 480px) {
  .nav {
    padding: 0 0.5rem;
  }
  
  .hero h1 {
    font-size: 2rem;
  }
  
  .hero p {
    font-size: 1rem;
  }
  
  .container {
    padding: 0 0.5rem;
  }
  
  .section-title {
    font-size: 2rem;
  }
  
  .book-info {
    padding: 1.5rem;
  }
  
  .book-title {
    font-size: 1.2rem;
  }
  
  .book-detail-info h1 {
    font-size: 1.8rem;
  }
  
  .btn {
    padding: 0.75rem 1.5rem;
    font-size: 0.9rem;
  }
}

/* Loading states */
.loading {
  display: flex;
  justify-content: center;
  align-items: center;
  padding: 4rem;
}

.spinner {
  width: 50px;
  height: 50px;
  border: 3px solid var(--border-color);
  border-top: 3px solid var(--highlight-color);
  border-radius: 50%;
  animation: spin 1s linear infinite;
}

@keyframes spin {
  0% { transform: rotate(0deg); }
  100% { transform: rotate(360deg); }
}

/* Estado vazio */
.empty-state {
  text-align: center;
  padding: 4rem 2rem;
  grid-column: 1 / -1;
}

.empty-state-icon {
  font-size: 4rem;
  margin-bottom: 1rem;
  opacity: 0.5;
}

.empty-state h3 {
  font-size: 1.5rem;
  color: var(--text-color);
  margin-bottom: 0.5rem;
}

.empty-state p {
  color: var(--text-secondary);
  font-size: 1rem;
}

/* Alertas */
.alert {
  padding: 1rem;
  border-radius: 6px;
  margin-bottom: 1rem;
}

.alert-success {
  background: #d4edda;
  color: #155724;
  border: 1px solid #c3e6cb;
}

.alert-error {
  background: #f8d7da;
  color: #721c24;
  border: 1px solid #f5c6cb;
}

/* Admin Styles */
.admin-form {
    background: #2a2a2a;
    padding: 2rem;
    border-radius: 8px;
    margin-bottom: 2rem;
    border: 1px solid #333;
}

.pdf-upload-section {
    background: #1e1e1e;
    padding: 1.5rem;
    border-radius: 6px;
    margin-bottom: 1.5rem;
    border: 2px dashed #6366f1;
}

.pdf-upload-section h3 {
    color: #6366f1;
    margin-bottom: 1rem;
}

.form-divider {
    text-align: center;
    margin: 1.5rem 0;
    position: relative;
}

.form-divider::before {
    content: '';
    position: absolute;
    top: 50%;
    left: 0;
    right: 0;
    height: 1px;
    background: #333;
}

.form-divider span {
    background: #1a1a1a;
    padding: 0 1rem;
    color: #888;
    position: relative;
    z-index: 1;
}

.pdf-processing {
    text-align: center;
    padding: 1rem;
    background: #2a2a2a;
    border-radius: 4px;
    border: 1px solid #6366f1;
}

.spinner {
    width: 20px;
    height: 20px;
    border: 2px solid #333;
    border-top: 2px solid #6366f1;
    border-radius: 50%;
    animation: spin 1s linear infinite;
    margin: 0 auto 0.5rem;
}

@keyframes spin {
    0% { transform: rotate(0deg); }
    100% { transform: rotate(360deg); }
}

.success-message {
    background: #10b981;
    color: white;
    padding: 1rem;
    border-radius: 4px;
    margin-top: 1rem;
}

.error-message {
    background: #ef4444;
    color: white;
    padding: 1rem;
    border-radius: 4px;
    margin-top: 1rem;
}

.livro-item {
    background: #2a2a2a;
    padding: 1.5rem;
    border-radius: 8px;
    margin-bottom: 1rem;
    border: 1px solid #333;
    display: flex;
    justify-content: space-between;
    align-items: flex-start;
    gap: 1rem;
}

.livro-info {
    flex: 1;
}

.livro-detalhes h4 {
    color: #fff;
    margin-bottom: 0.5rem;
    font-size: 1.2rem;
}

.livro-detalhes p {
    color: #ccc;
    margin-bottom: 0.25rem;
    font-size: 0.9rem;
}

.livro-acoes {
    display: flex;
    gap: 0.5rem;
    flex-direction: column;
    align-items: flex-end;
}

.btn-danger {
    background: #ef4444;
    color: white;
    border: none;
    padding: 0.5rem 1rem;
    border-radius: 4px;
    cursor: pointer;
    transition: background 0.2s;
    font-size: 0.9rem;
}

.btn-danger:hover {
    background: #dc2626;
}

.btn-secondary {
    background: #6b7280;
    color: white;
    text-decoration: none;
    padding: 0.5rem 1rem;
    border-radius: 4px;
    text-align: center;
    display: inline-block;
    transition: background 0.2s;
    font-size: 0.9rem;
}

.btn-secondary:hover {
    background: #4b5563;
}

.livros-list {
    max-height: 600px;
    overflow-y: auto;
    padding-right: 0.5rem;
}

.livros-list::-webkit-scrollbar {
    width: 6px;
}

.livros-list::-webkit-scrollbar-track {
    background: #2a2a2a;
    border-radius: 3px;
}

.livros-list::-webkit-scrollbar-thumb {
    background: #6366f1;
    border-radius: 3px;
}

.empty-state {
    text-align: center;
    padding: 3rem;
    color: #888;
    background: #2a2a2a;
    border-radius: 8px;
    border: 1px solid #333;
}

.empty-state h3 {
    color: #ccc;
    margin-bottom: 0.5rem;
}

/* About Section */
.about-section {
    padding: 6rem 0;
    background: linear-gradient(135deg, #1a1a1a 0%, #2a2a2a 100%);
    border-top: 1px solid #333;
}

.about-content {
    max-width: 1000px;
    margin: 0 auto;
}

.about-description {
    font-size: 1.2rem;
    line-height: 1.8;
    color: var(--text-secondary);
    margin-bottom: 3rem;
    text-align: center;
}

.about-features {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(250px, 1fr));
    gap: 2rem;
    margin-bottom: 3rem;
}

.feature {
    background: #2a2a2a;
    padding: 2rem;
    border-radius: 12px;
    text-align: center;
    border: 1px solid #333;
    transition: var(--transition);
}

.feature:hover {
    transform: translateY(-5px);
    border-color: var(--accent-color);
    box-shadow: 0 10px 30px rgba(99, 102, 241, 0.1);
}

.feature-icon {
    font-size: 3rem;
    margin-bottom: 1rem;
    display: block;
}

.feature h3 {
    color: var(--text-color);
    margin-bottom: 1rem;
    font-size: 1.3rem;
}

.feature p {
    color: var(--text-secondary);
    line-height: 1.6;
}

.about-stats {
    display: flex;
    justify-content: center;
    gap: 3rem;
    margin: 3rem 0;
    padding: 2rem;
    background: #2a2a2a;
    border-radius: 12px;
    border: 1px solid #333;
}

.stat {
    text-align: center;
}

.stat-number {
    display: block;
    font-size: 3rem;
    font-weight: 700;
    color: var(--accent-color);
    margin-bottom: 0.5rem;
    background: linear-gradient(135deg, var(--accent-color), #8b5cf6);
    -webkit-background-clip: text;
    -webkit-text-fill-color: transparent;
    background-clip: text;
}

.stat-label {
    color: var(--text-secondary);
    font-size: 1rem;
    text-transform: uppercase;
    letter-spacing: 1px;
}

.about-mission {
    background: #1e1e1e;
    padding: 2rem;
    border-radius: 12px;
    margin: 2rem 0;
    border-left: 4px solid var(--accent-color);
}

.about-mission h3 {
    color: var(--text-color);
    margin-bottom: 1rem;
    font-size: 1.4rem;
}

.about-mission p {
    color: var(--text-secondary);
    line-height: 1.7;
    font-size: 1.1rem;
}

.about-tech {
    margin-top: 2rem;
}

.about-tech h3 {
    color: var(--text-color);
    margin-bottom: 1rem;
    font-size: 1.4rem;
}

.tech-stack {
    display: flex;
    flex-wrap: wrap;
    gap: 1rem;
}

.tech-item {
    background: var(--accent-color);
    color: white;
    padding: 0.5rem 1rem;
    border-radius: 20px;
    font-size: 0.9rem;
    font-weight: 500;
    transition: var(--transition);
}

.tech-item:hover {
    background: #8b5cf6;
    transform: scale(1.05);
}

.back-to-home {
    text-align: center;
    margin-top: 3rem;
}

.back-to-home .btn {
    display: inline-block;
    background: var(--accent-color);
    color: white;
    padding: 1rem 2rem;
    border-radius: 8px;
    text-decoration: none;
    font-weight: 600;
    transition: var(--transition);
    box-shadow: 0 4px 15px rgba(99, 102, 241, 0.3);
}

.back-to-home .btn:hover {
    background: #8b5cf6;
    transform: translateY(-2px);
    box-shadow: 0 6px 20px rgba(99, 102, 241, 0.4);
}

/* Responsive adjustments for about section */
@media (max-width: 768px) {
    .about-section {
        padding: 4rem 0;
    }
    
    .about-features {
        grid-template-columns: 1fr;
        gap: 1.5rem;
    }
    
    .about-stats {
        flex-direction: column;
        gap: 1.5rem;
    }
    
    .stat-number {
        font-size: 2rem;
    }
    
    .tech-stack {
        justify-content: center;
    }
}

/* Media query para celulares muito pequenos */
@media (max-width: 480px) {
  .nav {
    padding: 0.5rem;
  }
  
  .nav-links a {
    font-size: 0.8rem;
    padding: 0.4rem 0.6rem;
  }
  
  .hero {
    padding: 1.5rem 0;
  }
  
  .hero h1 {
    font-size: 1.75rem;
  }
  
  .hero p {
    font-size: 0.9rem;
  }
  
  .books-grid {
    gap: 0.75rem;
  }
  
  .book-card {
    height: 300px;
  }
  
  .book-image {
    height: 180px;
  }
  
  .book-image img {
    object-fit: cover;
    width: 100%;
    height: 100%;
  }
  
  .book-info {
    padding: 0.5rem;
  }
  
  .book-info h3 {
    font-size: 0.85rem;
  }
  
  .book-info .author {
    font-size: 0.75rem;
  }
  
  .book-info .category {
    font-size: 0.7rem;
  }
  
  .container {
    padding: 0 0.75rem;
  }
}