/* --- 1. Variables y Base --- */
:root {
    --ukbi-primary: #1a472a;
    --ukbi-secondary: #2e7d32;
    --ukbi-accent: #fbc02d;
    --ukbi-bg: #f4f7f6;
    --ukbi-card: #ffffff;
    --ukbi-text: #2c3e50;
    --ukbi-shadow: 0 10px 20px rgba(0,0,0,0.1);
    --font-main: 'Segoe UI', Tahoma, Geneva, Verdana, sans-serif;
}

body {
    background-color: var(--ukbi-bg);
    font-family: var(--font-main);
    color: var(--ukbi-text);
    margin: 0;
    line-height: 1.6;
}

/* --- 2. Header & Hero --- */
.library-header {
    background: var(--ukbi-primary);
    color: white;
    padding: 20px 5%;
}

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

.library-nav a {
    color: white;
    text-decoration: none;
    border: 1px solid white;
    padding: 8px 16px;
    border-radius: 4px;
    transition: 0.3s;
}

.library-nav a:hover {
    background: white;
    color: var(--ukbi-primary);
}

.library-hero {
    text-align: center;
    padding: 60px 5%;
    background: linear-gradient(rgba(26, 71, 42, 0.9), rgba(26, 71, 42, 0.9)), 
                url('../assets/library-bg.jpg');
    background-size: cover;
    color: white;
}

/* --- 3. Buscador y Filtros --- */
.library-controls {
    margin-top: 30px;
    max-width: 800px;
    margin-left: auto;
    margin-right: auto;
}

#librarySearch {
    width: 100%;
    padding: 15px;
    border-radius: 30px;
    border: none;
    font-size: 1.1em;
    margin-bottom: 20px;
    box-shadow: var(--ukbi-shadow);
}

.filter-group {
    display: flex;
    justify-content: center;
    gap: 10px;
    flex-wrap: wrap;
}

.filter-btn {
    background: rgba(255,255,255,0.2);
    border: 1px solid white;
    color: white;
    padding: 8px 20px;
    border-radius: 20px;
    cursor: pointer;
    transition: 0.3s;
}

.filter-btn.active, .filter-btn:hover {
    background: var(--ukbi-accent);
    color: var(--ukbi-primary);
    border-color: var(--ukbi-accent);
}

/* --- 4. La Cuadrícula de Libros (Refactorizada) --- */
.library-grid-container {
    max-width: 1200px;
    margin: -40px auto 40px;
    padding: 0 20px;
}

.books-grid {
    display: grid;
    grid-template-columns: repeat(auto-fill, minmax(240px, 1fr)); /* Aumentado un poco el ancho mínimo */
    gap: 30px;
}

.book-card {
    background: var(--ukbi-card);
    border-radius: 12px;
    overflow: hidden;
    box-shadow: var(--ukbi-shadow);
    transition: transform 0.3s ease;
    display: flex;
    flex-direction: column;
    height: 100%; /* Asegura que todas las tarjetas midan lo mismo */
}

.book-card:hover {
    transform: translateY(-10px);
}

/* Contenedor del Canvas */
.book-cover {
    width: 100%;
    aspect-ratio: 3 / 4; /* Mantiene una proporción de portada de libro */
    background: #e0e0e0; /* Color neutro mientras carga */
    position: relative;
    display: flex;
    justify-content: center;
    align-items: center;
    overflow: hidden;
}

/* Estilo específico para el Canvas */
.pdf-preview {
    width: 100% !important;
    height: 100% !important;
    object-fit: contain; /* Clave para que la vista previa llene el espacio sin salirse */
    display: block;
}

.category-tag {
    position: absolute;
    top: 15px;
    right: 15px;
    background: var(--ukbi-accent);
    color: var(--ukbi-primary);
    font-size: 0.75em;
    font-weight: bold;
    padding: 5px 12px;
    border-radius: 4px;
    text-transform: uppercase;
    z-index: 10; /* Asegura que esté sobre el canvas */
    box-shadow: 0 2px 5px rgba(0,0,0,0.2);
}

.book-info {
    padding: 25px;
    text-align: center;
    flex-grow: 1;
    display: flex;
    flex-direction: column;
    background: white;
}

.book-info h3 {
    margin: 0 0 12px;
    font-size: 1.3em;
    color: var(--ukbi-primary);
    font-weight: 700;
}

.book-info p {
    font-size: 0.95em;
    color: #555;
    margin-bottom: 25px;
    flex-grow: 1;
}

.download-btn {
    background: var(--ukbi-primary);
    color: white;
    text-decoration: none;
    padding: 12px 20px;
    border-radius: 8px;
    font-weight: bold;
    transition: background 0.3s;
    display: inline-block;
}

.download-btn:hover {
    background: var(--ukbi-secondary);
}

/* --- 5. Footer --- */
footer {
    text-align: center;
    padding: 30px;
    background: var(--ukbi-primary);
    color: white;
    margin-top: 50px;
}