/* ===== VARIABLES CSS ===== */
:root {
  /* Colores principales */
  --primary-blue: #0066cc;
  --primary-purple: #667eea;
  --primary-gradient: linear-gradient(135deg, #667eea 0%, #764ba2 100%);
  --secondary-gradient: linear-gradient(135deg, #0066cc 0%, #0ea5e9 100%);
  
  /* Colores de texto */
  --text-dark: #1a1a1a;
  --text-light: #666;
  --text-muted: #999;
  --white: #ffffff;
  
  /* Colores de categorías */
  --math-color: #ef4444;
  --programming-color: #8b5cf6;
  --stats-color: #06b6d4;
  --tutorials-color: #10b981;
  
  /* Espaciado */
  --container-width: 1200px;
  --section-padding: 5rem 0;
  --card-padding: 2rem;
  
  /* Sombras */
  --shadow-sm: 0 2px 8px rgba(0, 0, 0, 0.1);
  --shadow-md: 0 4px 16px rgba(0, 0, 0, 0.12);
  --shadow-lg: 0 8px 32px rgba(0, 0, 0, 0.15);
  
  /* Transiciones */
  --transition: all 0.3s cubic-bezier(0.4, 0, 0.2, 1);
  
  /* Tipografía */
  --font-family: 'Inter', 'Segoe UI', system-ui, sans-serif;
  --font-size-xs: 0.75rem;
  --font-size-sm: 0.875rem;
  --font-size-base: 1rem;
  --font-size-lg: 1.125rem;
  --font-size-xl: 1.25rem;
  --font-size-2xl: 1.5rem;
  --font-size-3xl: 1.875rem;
  --font-size-4xl: 2.25rem;
}

/* ===== RESET Y BASE ===== */
* {
  margin: 0;
  padding: 0;
  box-sizing: border-box;
}

html {
  scroll-behavior: smooth;
}

body {
  font-family: var(--font-family);
  font-size: var(--font-size-base);
  line-height: 1.6;
  color: var(--text-dark);
  background: #f8fafc;
  overflow-x: hidden;
}

.container {
  max-width: var(--container-width);
  margin: 0 auto;
  padding: 0 1rem;
}

/* ===== UTILIDADES ===== */
.text-gradient {
  background: var(--primary-gradient);
  -webkit-background-clip: text;
  background-clip: text;
  -webkit-text-fill-color: transparent;
  background-clip: text;
}

.btn {
  display: inline-flex;
  align-items: center;
  gap: 0.5rem;
  padding: 0.875rem 2rem;
  border: none;
  border-radius: 50px;
  font-weight: 600;
  text-decoration: none;
  transition: var(--transition);
  cursor: pointer;
  font-size: var(--font-size-sm);
}

.btn-primary {
  background: var(--primary-gradient);
  color: var(--white);
  box-shadow: var(--shadow-md);
}

.btn-primary:hover {
  transform: translateY(-2px);
  box-shadow: var(--shadow-lg);
  color: var(--white);
}

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

.btn-outline:hover {
  background: var(--primary-blue);
  color: var(--white);
  transform: translateY(-2px);
}

/* ===== HERO SECTION ===== */
.blog-hero {
  position: relative;
  background: var(--primary-gradient);
  color: var(--white);
  padding: 8rem 0 6rem;
  overflow: hidden;
  min-height: 70vh;
  display: flex;
  align-items: center;
}

.hero-bg {
  position: absolute;
  top: 0;
  left: 0;
  right: 0;
  bottom: 0;
  background: 
    radial-gradient(circle at 20% 80%, rgba(255, 255, 255, 0.1) 0%, transparent 50%),
    radial-gradient(circle at 80% 20%, rgba(255, 255, 255, 0.1) 0%, transparent 50%);
}

.hero-content {
  position: relative;
  z-index: 2;
  text-align: center;
  max-width: 800px;
  margin: 0 auto;
}

.hero-badge {
  display: inline-flex;
  align-items: center;
  gap: 0.5rem;
  background: rgba(255, 255, 255, 0.15);
  backdrop-filter: blur(10px);
  border: 1px solid rgba(255, 255, 255, 0.2);
  padding: 0.5rem 1rem;
  border-radius: 50px;
  font-size: var(--font-size-sm);
  font-weight: 600;
  margin-bottom: 2rem;
  animation: slideInDown 1s ease-out;
}

.blog-hero h1 {
  font-size: var(--font-size-4xl);
  font-weight: 800;
  margin-bottom: 1.5rem;
  line-height: 1.2;
  animation: slideInUp 1s ease-out 0.2s both;
}

.blog-hero p {
  font-size: var(--font-size-xl);
  opacity: 0.9;
  margin-bottom: 3rem;
  max-width: 600px;
  margin-left: auto;
  margin-right: auto;
  animation: slideInUp 1s ease-out 0.4s both;
}

.hero-stats {
  display: flex;
  justify-content: center;
  gap: 3rem;
  animation: slideInUp 1s ease-out 0.6s both;
}

.stat-item {
  text-align: center;
}

.stat-number {
  font-size: var(--font-size-3xl);
  font-weight: 800;
  color: var(--white);
  line-height: 1;
}

.stat-label {
  font-size: var(--font-size-sm);
  opacity: 0.8;
  margin-top: 0.5rem;
}

/* ===== FILTROS Y BÚSQUEDA ===== */
.blog-filters {
  background: var(--white);
  padding: 2rem 0;
  border-bottom: 1px solid #e2e8f0;
  position: sticky;
  top: 80px;
  z-index: 100;
  box-shadow: var(--shadow-sm);
}

.filters-wrapper {
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 2rem;
}

.search-box {
  position: relative;
  flex: 1;
  max-width: 400px;
}

.search-box i {
  position: absolute;
  left: 1rem;
  top: 50%;
  transform: translateY(-50%);
  color: var(--text-muted);
}

.search-box input {
  width: 100%;
  padding: 0.875rem 1rem 0.875rem 3rem;
  border: 2px solid #e2e8f0;
  border-radius: 50px;
  font-size: var(--font-size-sm);
  transition: var(--transition);
  background: #f8fafc;
}

.search-box input:focus {
  outline: none;
  border-color: var(--primary-blue);
  background: var(--white);
  box-shadow: 0 0 0 3px rgba(0, 102, 204, 0.1);
}

.category-filters {
  display: flex;
  gap: 0.5rem;
  flex-wrap: wrap;
}

.filter-btn {
  display: flex;
  align-items: center;
  gap: 0.5rem;
  padding: 0.75rem 1.5rem;
  background: #f1f5f9;
  border: none;
  border-radius: 50px;
  font-size: var(--font-size-sm);
  font-weight: 500;
  color: var(--text-dark);
  cursor: pointer;
  transition: var(--transition);
  white-space: nowrap;
}

.filter-btn:hover {
  background: #e2e8f0;
  transform: translateY(-2px);
}

.filter-btn.active {
  background: var(--primary-gradient);
  color: var(--white);
  box-shadow: var(--shadow-md);
}

/* ===== GRID DE ARTÍCULOS ===== */
.blog-grid {
  padding: 4rem 0;
  background: #f8fafc;
}

.articles-grid {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(350px, 1fr));
  gap: 2rem;
  margin-bottom: 3rem;
}

.article-card {
  background: var(--white);
  border-radius: 20px;
  overflow: hidden;
  box-shadow: var(--shadow-sm);
  transition: var(--transition);
  height: fit-content;
}

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

.article-card.featured {
  grid-column: span 2;
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: 0;
}

.article-image {
  position: relative;
  height: 250px;
  overflow: hidden;
}

.article-card.featured .article-image {
  height: 100%;
}

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

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

.article-badge {
  position: absolute;
  top: 1rem;
  left: 1rem;
  background: var(--primary-gradient);
  color: var(--white);
  padding: 0.5rem 1rem;
  border-radius: 50px;
  font-size: var(--font-size-xs);
  font-weight: 600;
  text-transform: uppercase;
  letter-spacing: 0.5px;
}

.read-time {
  position: absolute;
  top: 1rem;
  right: 1rem;
  background: rgba(0, 0, 0, 0.7);
  color: var(--white);
  padding: 0.5rem 1rem;
  border-radius: 50px;
  font-size: var(--font-size-xs);
  font-weight: 500;
  backdrop-filter: blur(10px);
}

.article-content {
  padding: 2rem;
  display: flex;
  flex-direction: column;
  height: 100%;
}

.article-meta {
  display: flex;
  align-items: center;
  justify-content: space-between;
  margin-bottom: 1rem;
}

.category {
  padding: 0.25rem 0.75rem;
  border-radius: 50px;
  font-size: var(--font-size-xs);
  font-weight: 600;
  text-transform: uppercase;
  letter-spacing: 0.5px;
}

.category:contains("Matemáticas"),
.category[data-category="matematicas"] {
  background: #fef2f2;
  color: var(--math-color);
}

.category:contains("Programación"),
.category[data-category="programacion"] {
  background: #f3f4f6;
  color: var(--programming-color);
}

.category:contains("Estadística"),
.category[data-category="estadistica"] {
  background: #ecfeff;
  color: var(--stats-color);
}

.category:contains("Tutoriales"),
.category[data-category="tutoriales"] {
  background: #ecfdf5;
  color: var(--tutorials-color);
}

.date {
  font-size: var(--font-size-xs);
  color: var(--text-muted);
  font-weight: 500;
}

.article-content h3 {
  font-size: var(--font-size-xl);
  font-weight: 700;
  line-height: 1.3;
  margin-bottom: 1rem;
  color: var(--text-dark);
}

.article-card.featured h3 {
  font-size: var(--font-size-2xl);
}

.article-content p {
  color: var(--text-light);
  line-height: 1.6;
  margin-bottom: 1.5rem;
  flex-grow: 1;
}

.article-footer {
  display: flex;
  align-items: center;
  justify-content: space-between;
  margin-top: auto;
}

.author {
  display: flex;
  align-items: center;
  gap: 0.75rem;
}

.author img {
  width: 40px;
  height: 40px;
  border-radius: 50%;
  object-fit: cover;
}

.author span {
  font-size: var(--font-size-sm);
  font-weight: 500;
  color: var(--text-dark);
}

.read-more {
  display: flex;
  align-items: center;
  gap: 0.5rem;
  color: var(--primary-blue);
  text-decoration: none;
  font-weight: 600;
  font-size: var(--font-size-sm);
  transition: var(--transition);
}

.read-more:hover {
  color: var(--primary-purple);
  transform: translateX(4px);
}

/* ===== CARGAR MÁS ===== */
.load-more-container {
  text-align: center;
  margin-top: 3rem;
}

.load-more-btn {
  background: var(--white);
  color: var(--primary-blue);
  border: 2px solid var(--primary-blue);
  padding: 1rem 2rem;
  border-radius: 50px;
  font-weight: 600;
  cursor: pointer;
  transition: var(--transition);
  display: inline-flex;
  align-items: center;
  gap: 0.5rem;
}

.load-more-btn:hover {
  background: var(--primary-blue);
  color: var(--white);
  transform: translateY(-2px);
  box-shadow: var(--shadow-md);
}

/* ===== NEWSLETTER ===== */
.newsletter-section {
  background: var(--primary-gradient);
  color: var(--white);
  padding: 4rem 0;
}

.newsletter-content {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: 3rem;
  align-items: center;
}

.newsletter-text h3 {
  font-size: var(--font-size-2xl);
  font-weight: 700;
  margin-bottom: 1rem;
}

.newsletter-text p {
  opacity: 0.9;
  font-size: var(--font-size-lg);
}

.input-group {
  display: flex;
  background: var(--white);
  border-radius: 50px;
  padding: 0.5rem;
  box-shadow: var(--shadow-md);
}

.input-group input {
  flex: 1;
  border: none;
  padding: 1rem 1.5rem;
  font-size: var(--font-size-base);
  background: transparent;
  color: var(--text-dark);
}

.input-group input:focus {
  outline: none;
}

.input-group input::placeholder {
  color: var(--text-muted);
}

.input-group button {
  background: var(--primary-gradient);
  color: var(--white);
  border: none;
  padding: 1rem 2rem;
  border-radius: 50px;
  font-weight: 600;
  cursor: pointer;
  transition: var(--transition);
  display: flex;
  align-items: center;
  gap: 0.5rem;
}

.input-group button:hover {
  transform: scale(1.05);
}

/* ===== CTA SECTION ===== */
.cta-section {
  background: #f1f5f9;
  padding: 4rem 0;
  text-align: center;
}

.cta-content h2 {
  font-size: var(--font-size-3xl);
  font-weight: 700;
  color: var(--text-dark);
  margin-bottom: 1rem;
}

.cta-content p {
  font-size: var(--font-size-lg);
  color: var(--text-light);
  margin-bottom: 2rem;
  max-width: 600px;
  margin-left: auto;
  margin-right: auto;
}

.cta-buttons {
  display: flex;
  justify-content: center;
  gap: 1rem;
  flex-wrap: wrap;
}

/* ===== FOOTER ===== */
.footer {
  background: var(--text-dark);
  color: var(--white);
  padding: 3rem 0 1rem;
}

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

.footer-section h4 {
  font-size: var(--font-size-lg);
  font-weight: 600;
  margin-bottom: 1rem;
  color: var(--white);
}

.footer-section p {
  color: #cbd5e1;
  line-height: 1.6;
  margin-bottom: 1rem;
}

.footer-section ul {
  list-style: none;
}

.footer-section ul li {
  margin-bottom: 0.5rem;
}

.footer-section ul li a {
  color: #cbd5e1;
  text-decoration: none;
  transition: var(--transition);
}

.footer-section ul li a:hover {
  color: var(--white);
}

.social-links {
  display: flex;
  gap: 1rem;
  margin-top: 1rem;
}

.social-links a {
  display: flex;
  align-items: center;
  justify-content: center;
  width: 40px;
  height: 40px;
  background: rgba(255, 255, 255, 0.1);
  border-radius: 50%;
  color: var(--white);
  text-decoration: none;
  transition: var(--transition);
}

.social-links a:hover {
  background: var(--primary-blue);
  transform: translateY(-2px);
}

.contact-info {
  display: flex;
  flex-direction: column;
  gap: 0.75rem;
}

.contact-item {
  display: flex;
  align-items: center;
  gap: 0.75rem;
  color: #cbd5e1;
}

.contact-item i {
  color: var(--primary-blue);
  width: 16px;
}

.footer-bottom {
  border-top: 1px solid #374151;
  padding-top: 1rem;
  text-align: center;
}

.footer-bottom p {
  color: #9ca3af;
  margin: 0;
}

/* ===== WHATSAPP FLOTANTE ===== */
.whatsapp-float {
  position: fixed;
  bottom: 2rem;
  right: 2rem;
  width: 60px;
  height: 60px;
  background: #25d366;
  border-radius: 50%;
  display: flex;
  align-items: center;
  justify-content: center;
  color: var(--white);
  font-size: 1.5rem;
  text-decoration: none;
  box-shadow: var(--shadow-lg);
  z-index: 1000;
  transition: var(--transition);
  animation: pulse 2s infinite;
}

.whatsapp-float:hover {
  transform: scale(1.1);
  color: var(--white);
}

/* ===== ANIMACIONES ===== */
@keyframes slideInDown {
  from {
    opacity: 0;
    transform: translateY(-30px);
  }
  to {
    opacity: 1;
    transform: translateY(0);
  }
}

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

@keyframes pulse {
  0%, 100% {
    box-shadow: 0 0 0 0 rgba(37, 211, 102, 0.7);
  }
  50% {
    box-shadow: 0 0 0 20px rgba(37, 211, 102, 0);
  }
}

/* ===== RESPONSIVE ===== */
@media (max-width: 1024px) {
  .article-card.featured {
    grid-column: span 1;
    display: block;
  }
  
  .article-card.featured .article-image {
    height: 250px;
  }
  
  .filters-wrapper {
    flex-direction: column;
    gap: 1rem;
  }
  
  .search-box {
    max-width: 100%;
  }
}

@media (max-width: 768px) {
  .blog-hero {
    padding: 6rem 0 4rem;
    text-align: center;
  }
  
  .blog-hero h1 {
    font-size: var(--font-size-3xl);
  }
  
  .blog-hero p {
    font-size: var(--font-size-lg);
  }
  
  .hero-stats {
    gap: 2rem;
  }
  
  .stat-number {
    font-size: var(--font-size-2xl);
  }
  
  .articles-grid {
    grid-template-columns: 1fr;
    gap: 1.5rem;
  }
  
  .newsletter-content {
    grid-template-columns: 1fr;
    gap: 2rem;
    text-align: center;
  }
  
  .input-group {
    flex-direction: column;
    gap: 0.5rem;
    padding: 1rem;
  }
  
  .input-group button {
    border-radius: 50px;
    width: 100%;
    justify-content: center;
  }
  
  .cta-buttons {
    flex-direction: column;
    align-items: center;
  }
  
  .category-filters {
    justify-content: center;
  }
  
  .footer-content {
    grid-template-columns: 1fr;
    gap: 2rem;
    text-align: center;
  }
  
  .social-links {
    justify-content: center;
  }
}

@media (max-width: 480px) {
  .container {
    padding: 0 1rem;
  }
  
  .blog-hero {
    padding: 4rem 0 3rem;
  }
  
  .blog-hero h1 {
    font-size: var(--font-size-2xl);
  }
  
  .hero-stats {
    flex-direction: column;
    gap: 1rem;
  }
  
  .article-content {
    padding: 1.5rem;
  }
  
  .filter-btn {
    padding: 0.5rem 1rem;
    font-size: var(--font-size-xs);
  }
  
  .whatsapp-float {
    width: 50px;
    height: 50px;
    font-size: 1.25rem;
    bottom: 1rem;
    right: 1rem;
  }
}

/* ===== ESTADOS DE FILTRADO ===== */
.article-card.hidden {
  display: none;
}

.article-card.fade-in {
  animation: fadeIn 0.5s ease-in-out;
}

@keyframes fadeIn {
  from {
    opacity: 0;
    transform: translateY(20px);
  }
  to {
    opacity: 1;
    transform: translateY(0);
  }
}

/* ===== SCROLL SUAVE ===== */
html {
  scroll-behavior: smooth;
}

/* ===== FOCUS STATES ===== */
.filter-btn:focus,
.btn:focus,
.search-box input:focus {
  outline: 2px solid var(--primary-blue);
  outline-offset: 2px;
}