* {
     box-sizing: border-box;
     margin: 0;
     padding: 0;
}

body {
     font-family: system-ui, -apple-system, BlinkMacSystemFont, sans-serif;
     background: #fafafa;
     color: #1a1a1a;
     line-height: 1.6;
     min-height: 100vh;
     display: flex;
     flex-direction: column;
}

/* NAVBAR */
.navbar {
     position: fixed;
     top: 0;
     width: 100%;
     background: #ffffff;
     border-bottom: 1px solid #e0e0e0;
     z-index: 100;
     box-shadow: 0 1px 3px rgba(0, 0, 0, 0.05);
}

.navbar .container {
     display: flex;
     justify-content: space-between;
     align-items: center;
     padding: 1.2rem 1rem;
     gap: 1rem;
}

.navbar strong {
     font-size: 1.1rem;
     color: #1a1a1a;
}

.navbar a {
     text-decoration: none;
     transition: opacity 0.2s ease;
}

.navbar a:hover {
     opacity: 0.7;
}

.navbar span {
     color: #666;
     font-size: 0.9rem;
}

/* LAYOUT */
.container {
     max-width: 760px;
     margin: 0 auto;
     padding: 0 1rem;
     width: 100%;
}

.main {
     padding-top: 6rem;
     padding-bottom: 3rem;
     flex: 1;
}

h1 {
     margin-bottom: 0.5rem;
     font-size: 2rem;
     color: #1a1a1a;
}

.subtitle {
     color: #666;
     margin-bottom: 2.5rem;
     font-size: 1.05rem;
}

/* BOOKS */
.book {
     background: #ffffff;
     border-radius: 8px;
     margin-bottom: 1.2rem;
     overflow: hidden;
     border: 1px solid #e0e0e0;
     transition: box-shadow 0.2s ease, border-color 0.2s ease;
}

.book:hover {
     box-shadow: 0 2px 8px rgba(0, 0, 0, 0.08);
     border-color: #d0d0d0;
}

.book-toggle {
     width: 100%;
     background: none;
     border: none;
     padding: 1.2rem 1rem;
     font-size: 1.05rem;
     font-weight: 600;
     display: flex;
     justify-content: space-between;
     align-items: center;
     cursor: pointer;
     color: #1a1a1a;
     transition: background 0.2s ease;
}

.book-toggle:hover {
     background: #f8f8f8;
}

.book-toggle .icon {
     font-size: 1.3rem;
     color: #666;
     font-weight: 300;
}

.book-content {
     display: none;
     padding: 1.5rem 1rem;
     border-top: 1px solid #e8e8e8;
     background: #fafafa;
}

.book-inner {
     display: flex;
     gap: 1.5rem;
}

.book-image {
     flex-shrink: 0;
}

.book-image img {
     width: 120px;
     height: 160px;
     border-radius: 6px;
     object-fit: cover;
     box-shadow: 0 2px 8px rgba(0, 0, 0, 0.12);
}

.book-info {
     flex: 1;
     display: flex;
     flex-direction: column;
}

.book-info p {
     margin-bottom: 0.8rem;
     color: #444;
     line-height: 1.5;
}

.book-info ul {
     margin-left: 1.2rem;
     margin-bottom: 1.2rem;
     flex: 1;
}

.book-info li {
     color: #555;
     margin-bottom: 0.4rem;
}

.book-footer {
     display: flex;
     justify-content: space-between;
     align-items: center;
     margin-top: auto;
     gap: 1rem;
     flex-wrap: wrap;
}

.price {
     font-weight: 700;
     font-size: 1.3rem;
     color: #1a1a1a;
}

.book-actions {
     display: flex;
     gap: 0.6rem;
}

.btn {
     text-decoration: none;
     color: #ffffff;
     padding: 0.6rem 1.2rem;
     border-radius: 6px;
     font-weight: 500;
     font-size: 0.9rem;
     transition: all 0.2s ease;
     display: inline-block;
     text-align: center;
}

.btn-whatsapp {
     background: #25d366;
}

.btn-whatsapp:hover {
     background: #20ba5a;
     transform: translateY(-1px);
}

.btn-email {
     background: #1a1a1a;
}

.btn-email:hover {
     background: #333;
     transform: translateY(-1px);
}

.btn:active {
     transform: translateY(0);
}

/* FOOTER */
.footer {
     background: #1a1a1a;
     color: #e0e0e0;
     margin-top: auto;
     padding: 3rem 0 1.5rem;
}

.footer-content {
     display: grid;
     grid-template-columns: 1fr 1fr;
     gap: 3rem;
     margin-bottom: 2rem;
}

.footer-section h3 {
     color: #ffffff;
     font-size: 1.1rem;
     margin-bottom: 1rem;
     font-weight: 600;
}

.footer-section p {
     color: #b0b0b0;
     line-height: 1.6;
     font-size: 0.95rem;
}

.contact-list {
     list-style: none;
}

.contact-list li {
     margin-bottom: 0.6rem;
}

.contact-list a {
     color: #e0e0e0;
     text-decoration: none;
     transition: color 0.2s ease;
     font-size: 0.95rem;
}

.contact-list a:hover {
     color: #ffffff;
     text-decoration: underline;
}

.footer-bottom {
     border-top: 1px solid #333;
     padding-top: 1.5rem;
     text-align: center;
}

.footer-bottom p {
     color: #888;
     font-size: 0.85rem;
}

/* RESPONSIVE */
@media (max-width: 640px) {
     .book-inner {
          flex-direction: column;
     }

     .book-image {
          align-self: center;
     }

     .book-footer {
          flex-direction: column;
          align-items: flex-start;
          gap: 1rem;
     }

     .book-actions {
          width: 100%;
     }

     .btn {
          flex: 1;
          min-width: 0;
     }

     .footer-content {
          grid-template-columns: 1fr;
          gap: 2rem;
     }

     h1 {
          font-size: 1.6rem;
     }

     .navbar .container {
          flex-wrap: wrap;
          gap: 0.5rem;
     }
}