/* ============================== 
   IMPORTACIÓN DE FUENTES
   ============================== */
@import url('https://fonts.googleapis.com/css2?family=Oswald:wght@400;500;600;700&family=Poppins:wght@300;400;500;600;700;800&display=swap');

/* ============================== 
   VARIABLES CSS
   ============================== */
:root {
    --primary-color: #2c3e50;
    --secondary-color: #3498db;
    --accent-color: #e74c3c;
    --success-color: #27ae60;
    --warning-color: #f39c12;
    --dark-color: #111111;
    --light-color: #ffffff;
    --gray-light: #f8f9fa;
    --gray-medium: #6c757d;
    --gray-dark: #343a40;
    --gradient-primary: linear-gradient(135deg, #667eea 0%, #764ba2 100%);
    --gradient-secondary: linear-gradient(135deg, #f093fb 0%, #f5576c 100%);
    --gradient-accent: linear-gradient(135deg, #4facfe 0%, #00f2fe 100%);
    --shadow-light: 0 2px 10px rgba(0,0,0,0.1);
    --shadow-medium: 0 4px 20px rgba(0,0,0,0.15);
    --shadow-heavy: 0 8px 30px rgba(0,0,0,0.2);
    --border-radius: 12px;
    --transition: all 0.3s cubic-bezier(0.4, 0, 0.2, 1);
}

/* ============================== 
   ESTILO GLOBAL
   ============================== */
* {
    margin: 0;
    padding: 0;
    box-sizing: border-box;
    list-style: none;
}

body {
    font-family: 'Poppins', sans-serif;
    background: linear-gradient(135deg, #f5f7fa 0%, #c3cfe2 100%);
    min-height: 100vh;
    line-height: 1.6;
    color: var(--dark-color);
    overflow-x: hidden;
}

img {
    max-width: 100%;
    height: auto;
}

/* ============================== 
   CONTENEDOR GENERAL
   ============================== */
.container {
    max-width: 1200px;
    margin: 0 auto;
    padding: 0 20px;
}

/* ============================== 
   ENCABEZADO (HEADER)
   ============================== */
.header {
    position: relative;
    background: var(--dark-color);
    padding: 60px 20px;
    min-height: 200px;
    display: flex;
    align-items: center;
    justify-content: center;
    text-align: center;
    overflow: hidden;
}

.header-background {
    position: absolute;
    top: 0;
    left: 0;
    right: 0;
    bottom: 0;
    background: var(--dark-color);
}

.header-pattern {
    position: absolute;
    top: 0;
    left: 0;
    right: 0;
    bottom: 0;
    background-image: 
        radial-gradient(circle at 25% 25%, rgba(255,255,255,0.05) 0%, transparent 50%),
        radial-gradient(circle at 75% 75%, rgba(255,255,255,0.05) 0%, transparent 50%);
    animation: float 6s ease-in-out infinite;
}

@keyframes float {
    0%, 100% { transform: translateY(0px); }
    50% { transform: translateY(-10px); }
}

.header-content {
    position: relative;
    z-index: 2;
    display: flex;
    align-items: center;
    justify-content: center;
    text-align: center;
    padding: 20px;
}

.header-txt {
    animation: slideInUp 0.8s ease-out;
}

@keyframes slideInUp {
    from {
        opacity: 0;
        transform: translateY(30px);
    }
    to {
        opacity: 1;
        transform: translateY(0);
    }
}

.header-icon {
    margin-bottom: 20px;
    animation: bounce 2s infinite;
}

.header-logo {
    width: 120px;
    height: 120px;
    object-fit: contain;
    filter: brightness(0) invert(1);
    transition: var(--transition);
}

.header-logo:hover {
    transform: scale(1.1);
    filter: brightness(0) invert(1) drop-shadow(0 0 10px rgba(255,255,255,0.3));
}

@keyframes bounce {
    0%, 20%, 50%, 80%, 100% { transform: translateY(0); }
    40% { transform: translateY(-10px); }
    60% { transform: translateY(-5px); }
}

.header-txt h1 {
    font-size: 3rem;
    margin-bottom: 15px;
    color: var(--light-color);
    font-family: 'Oswald', sans-serif;
    text-transform: uppercase;
    font-weight: 700;
    text-shadow: 2px 2px 4px rgba(0,0,0,0.3);
    letter-spacing: 2px;
}

.header-txt p {
    font-size: 1.3rem;
    color: rgba(255,255,255,0.9);
    font-weight: 300;
    letter-spacing: 1px;
}

/* ============================== 
   NAVEGACIÓN
   ============================== */
.nav-section {
    text-align: right;
    margin: 20px 0;
    padding: 10px 0;
}

.btn-circular {
    display: inline-flex;
    align-items: center;
    gap: 8px;
    padding: 12px 24px;
    background: var(--light-color);
    color: var(--primary-color);
    text-decoration: none;
    border-radius: 50px;
    font-weight: 600;
    font-size: 14px;
    box-shadow: var(--shadow-light);
    transition: var(--transition);
    border: 2px solid transparent;
}

.btn-circular:hover {
    background: var(--primary-color);
    color: var(--light-color);
    transform: translateY(-2px);
    box-shadow: var(--shadow-medium);
}

/* ============================== 
   SECCIÓN DE BIENVENIDA
   ============================== */
.welcome-section {
    padding: 40px 0;
    background: var(--light-color);
    position: relative;
}

.welcome-content {
    text-align: center;
    position: relative;
    padding: 40px 20px;
}

.welcome-content h2 {
    font-size: 2.5rem;
    color: var(--primary-color);
    font-family: 'Oswald', sans-serif;
    text-transform: uppercase;
    margin-bottom: 15px;
    font-weight: 600;
    letter-spacing: 1px;
}

.welcome-content h3 {
    font-size: 1.3rem;
    color: var(--gray-medium);
    font-weight: 400;
    margin-bottom: 30px;
    line-height: 1.5;
}

.welcome-decoration {
    width: 80px;
    height: 4px;
    background: var(--gradient-accent);
    margin: 0 auto;
    border-radius: 2px;
    position: relative;
}

.welcome-decoration::before,
.welcome-decoration::after {
    content: '';
    position: absolute;
    width: 20px;
    height: 4px;
    background: var(--gradient-accent);
    border-radius: 2px;
}

.welcome-decoration::before {
    left: -30px;
    top: 0;
}

.welcome-decoration::after {
    right: -30px;
    top: 0;
}

/* ============================== 
   SECCIÓN DE LIBROS
   ============================== */
.books-section {
    padding: 60px 0;
    background: var(--gray-light);
    position: relative;
}

#book-list {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(350px, 1fr));
    gap: 30px;
    padding: 20px 0;
}

.book-card {
    background: var(--light-color);
    border-radius: var(--border-radius);
    box-shadow: var(--shadow-light);
    overflow: hidden;
    transition: var(--transition);
    position: relative;
    border: 1px solid rgba(0,0,0,0.05);
    opacity: 1 !important;
    visibility: visible !important;
}

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

.book-card::before {
    content: '';
    position: absolute;
    top: 0;
    left: 0;
    right: 0;
    height: 4px;
    background: var(--gradient-accent);
}

.book-header {
    padding: 20px 20px 15px;
    background: linear-gradient(135deg, #f8f9fa 0%, #e9ecef 100%);
    border-bottom: 1px solid rgba(0,0,0,0.05);
    display: flex;
    align-items: center;
    gap: 15px;
}

.book-icon {
    width: 50px;
    height: 50px;
    background: var(--gradient-primary);
    border-radius: 50%;
    display: flex;
    align-items: center;
    justify-content: center;
    color: var(--light-color);
    font-size: 1.2rem;
    box-shadow: var(--shadow-light);
}

.book-header h4 {
    font-size: 1.2rem;
    color: var(--primary-color);
    font-weight: 600;
    margin: 0;
    flex: 1;
}

.book-content {
    padding: 0;
    position: relative;
}

.book-content iframe {
    width: 100%;
    height: 250px;
    border: none;
    display: block;
    opacity: 1 !important;
    visibility: visible !important;
}

.book-footer {
    padding: 15px 20px;
    background: var(--gray-light);
    border-top: 1px solid rgba(0,0,0,0.05);
}

.book-level {
    font-size: 0.9rem;
    color: var(--gray-medium);
    font-weight: 500;
    background: var(--light-color);
    padding: 5px 12px;
    border-radius: 20px;
    display: inline-block;
    border: 1px solid rgba(0,0,0,0.1);
}

/* ============================== 
   PIE DE PÁGINA (FOOTER)
   ============================== */
.footer {
    position: relative;
    background: var(--dark-color);
    color: var(--light-color);
    padding: 60px 0 40px;
    overflow: hidden;
}

.footer-background {
    position: absolute;
    top: 0;
    left: 0;
    right: 0;
    bottom: 0;
    background: var(--dark-color);
}

.footer-pattern {
    position: absolute;
    top: 0;
    left: 0;
    right: 0;
    bottom: 0;
    background-image: 
        radial-gradient(circle at 20% 20%, rgba(255,255,255,0.05) 0%, transparent 50%),
        radial-gradient(circle at 80% 80%, rgba(255,255,255,0.05) 0%, transparent 50%);
}

.footer-content {
    position: relative;
    z-index: 2;
    display: grid;
    grid-template-columns: 1fr 1fr;
    gap: 40px;
    align-items: start;
}

.footer-section {
    background: rgba(255,255,255,0.05);
    padding: 30px;
    border-radius: var(--border-radius);
    backdrop-filter: blur(10px);
    border: 1px solid rgba(255,255,255,0.1);
    transition: var(--transition);
}

.footer-section:hover {
    background: rgba(255,255,255,0.08);
    transform: translateY(-2px);
}

.section-header {
    display: flex;
    align-items: center;
    gap: 15px;
    margin-bottom: 20px;
    padding-bottom: 15px;
    border-bottom: 2px solid var(--secondary-color);
}

.section-header i {
    font-size: 1.5rem;
    color: var(--secondary-color);
}

.section-header h3 {
    font-size: 1.3rem;
    color: var(--light-color);
    font-family: 'Oswald', sans-serif;
    text-transform: uppercase;
    margin: 0;
    font-weight: 600;
    letter-spacing: 1px;
}

.section-content {
    color: rgba(255,255,255,0.9);
}

.footer-link {
    display: inline-flex;
    align-items: center;
    gap: 10px;
    color: var(--secondary-color);
    text-decoration: none;
    font-weight: 500;
    padding: 10px 15px;
    background: rgba(52, 152, 219, 0.1);
    border-radius: 8px;
    transition: var(--transition);
    margin-bottom: 20px;
}

.footer-link:hover {
    background: rgba(52, 152, 219, 0.2);
    transform: translateX(5px);
}

.footer-image {
    text-align: center;
    margin-top: 20px;
}

.footer-image img {
    border-radius: 8px;
    box-shadow: var(--shadow-medium);
    transition: var(--transition);
    max-width: 100%;
    height: auto;
}

.footer-image img:hover {
    transform: scale(1.02);
}

/* ============================== 
   FORMULARIO DE COMENTARIOS
   ============================== */
.comment-form {
    margin-top: 20px;
}

.form-group {
    margin-bottom: 20px;
}

.form-group textarea {
    width: 100%;
    padding: 15px;
    border: 2px solid rgba(255,255,255,0.2);
    border-radius: 8px;
    background: rgba(255,255,255,0.1);
    color: var(--light-color);
    font-size: 16px;
    resize: vertical;
    min-height: 120px;
    transition: var(--transition);
    backdrop-filter: blur(10px);
}

.form-group textarea:focus {
    outline: none;
    border-color: var(--secondary-color);
    background: rgba(255,255,255,0.15);
    box-shadow: 0 0 0 3px rgba(52, 152, 219, 0.2);
}

.form-group textarea::placeholder {
    color: rgba(255,255,255,0.6);
}

.btn-submit {
    display: inline-flex;
    align-items: center;
    gap: 10px;
    background: var(--gradient-accent);
    color: var(--light-color);
    padding: 12px 24px;
    border: none;
    border-radius: 8px;
    font-size: 16px;
    font-weight: 600;
    cursor: pointer;
    transition: var(--transition);
    box-shadow: var(--shadow-light);
}

.btn-submit:hover {
    transform: translateY(-2px);
    box-shadow: var(--shadow-medium);
}

/* ============================== 
   RESPONSIVE
   ============================== */
@media (max-width: 768px) {
    .header {
        padding: 40px 20px;
        min-height: 150px;
    }

    .header-txt h1 {
        font-size: 2.2rem;
    }

    .header-txt p {
        font-size: 1.1rem;
    }

    .welcome-content h2 {
        font-size: 2rem;
    }

    .welcome-content h3 {
        font-size: 1.1rem;
    }

    #book-list {
        grid-template-columns: 1fr;
        gap: 20px;
    }

    .book-card {
        margin: 0 10px;
    }

    .footer-content {
        grid-template-columns: 1fr;
        gap: 30px;
    }

    .footer-section {
        padding: 20px;
    }

    .btn-circular {
        padding: 10px 20px;
        font-size: 13px;
    }
}

@media (max-width: 480px) {
    .container {
        padding: 0 15px;
    }

    .header-txt h1 {
        font-size: 1.8rem;
    }

    .book-header {
        flex-direction: column;
        text-align: center;
        gap: 10px;
    }

    .book-icon {
        width: 40px;
        height: 40px;
        font-size: 1rem;
    }

    .footer-section {
        padding: 15px;
    }
}

/* ============================== 
   ANIMACIONES ADICIONALES
   ============================== */
.book-card {
    animation: fadeInUp 0.6s ease-out;
}

.book-card:nth-child(1) { animation-delay: 0.1s; }
.book-card:nth-child(2) { animation-delay: 0.2s; }
.book-card:nth-child(3) { animation-delay: 0.3s; }
.book-card:nth-child(4) { animation-delay: 0.4s; }

@keyframes fadeInUp {
    from {
        opacity: 0;
        transform: translateY(30px);
    }
    to {
        opacity: 1;
        transform: translateY(0);
    }
}

/* ============================== 
   EFECTOS DE SCROLL
   ============================== */
.book-card {
    opacity: 1;
    transform: translateY(0);
    transition: var(--transition);
}

.book-card.visible {
    opacity: 1;
    transform: translateY(0);
}

/* ============================== 
   MEJORAS DE ACCESIBILIDAD
   ============================== */
.btn-circular:focus,
.btn-submit:focus {
    outline: 2px solid var(--secondary-color);
    outline-offset: 2px;
}

.book-card:focus-within {
    box-shadow: 0 0 0 3px rgba(52, 152, 219, 0.3);
}

/* ============================== 
   ESTADOS DE CARGA
   ============================== */
.loading {
    position: relative;
    overflow: hidden;
}

.loading::after {
    content: '';
    position: absolute;
    top: 0;
    left: -100%;
    width: 100%;
    height: 100%;
    background: linear-gradient(90deg, transparent, rgba(255,255,255,0.2), transparent);
    animation: loading 1.5s infinite;
}

@keyframes loading {
    0% { left: -100%; }
    100% { left: 100%; }
}

.menu-tabs {
    display: flex;
    gap: 10px;
    margin: 20px 0;
}

.tab-btn {
    padding: 10px 20px;
    border: none;
    background: #eee;
    cursor: pointer;
    border-radius: 8px;
    font-size: 16px;
    transition: 0.3s;
}

.tab-btn:hover {
    background: #ddd;
}

.tab-btn.active {
    background: #007bff;
    color: #fff;
}

.tab-content {
    display: none;
    margin-top: 20px;
}

.tab-content.active {
    display: block;
}