:root {
      --primary-color: #2c3e50;
      --secondary-color: #3498db;
      --accent-color: #e74c3c;
      --success-color: #27ae60;
      --warning-color: #f39c12;
      --text-color: #333;
      --text-light: #6c757d;
      --bg-color: #fff;
      --card-bg: #f8f9fa;
      --border-color: #e9ecef;
      --shadow: 0 4px 6px rgba(0,0,0,0.1);
      --shadow-lg: 0 10px 30px rgba(0,0,0,0.15);
      --gradient-primary: linear-gradient(135deg, var(--primary-color), var(--secondary-color));
      --gradient-secondary: linear-gradient(135deg, #f093fb 0%, #f5576c 100%);
      --transition: all 0.3s cubic-bezier(0.4, 0, 0.2, 1);
    }

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

    body {
      font-family: 'Segoe UI', Tahoma, Geneva, Verdana, sans-serif;
      line-height: 1.6;
      color: var(--text-color);
      min-height: 100vh;
    }

    .container {
      max-width: 1200px;
      margin: 0 auto;
      padding: 0 20px;
    }

    /* Header */
    .hero {
      background: var(--gradient-primary);
      color: white;
      padding: 4rem 0;
      text-align: center;
      position: relative;
      overflow: hidden;
    }

    .hero::before {
      content: '';
      position: absolute;
      top: -50%;
      left: -50%;
      width: 200%;
      height: 200%;
      background: linear-gradient(30deg, transparent, rgba(255,255,255,0.1), transparent);
      transform: rotate(30deg);
      animation: shine 8s ease-in-out infinite;
    }

    @keyframes shine {
      0%, 100% { transform: translateX(-100%) translateY(-100%) rotate(45deg); }
      50% { transform: translateX(100%) translateY(100%) rotate(45deg); }
    }

    .hero-content {
      position: relative;
      z-index: 2;
    }

    .hero-image i {
      font-size: 4rem;
      margin-bottom: 1rem;
      opacity: 0.9;
      animation: float 3s ease-in-out infinite;
    }

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

    .hero h1 {
      font-size: clamp(2rem, 5vw, 3rem);
      font-weight: 700;
      margin-bottom: 1rem;
      text-shadow: 2px 2px 4px rgba(0,0,0,0.3);
    }

    .hero p {
      font-size: clamp(1rem, 3vw, 1.2rem);
      opacity: 0.9;
      max-width: 600px;
      margin: 0 auto;
    }

    /* Navigation */
    nav {
      background: rgba(255, 255, 255, 0.95);
      backdrop-filter: blur(10px);
      padding: 1rem 0;
      box-shadow: var(--shadow);
      position: sticky;
      top: 0;
      z-index: 100;
    }

    .nav-container {
      display: flex;
      justify-content: center;
      align-items: center;
      flex-wrap: wrap;
      gap: 1rem;
    }

    .nav-links {
      display: flex;
      list-style: none;
      gap: 0.5rem;
      flex-wrap: wrap;
    }

    .nav-links a {
      color: var(--text-color);
      text-decoration: none;
      font-weight: 500;
      padding: 0.5rem 1rem;
      border-radius: 25px;
      transition: var(--transition);
      white-space: nowrap;
    }

    .nav-links a:hover,
    .nav-links a.active {
      background: var(--secondary-color);
      color: white;
      transform: translateY(-2px);
    }

    /* Main Content */
    .section {
      background: var(--bg-color);
      padding: 2rem 0;
      min-height: 100vh;
    }

    .section-title {
      font-size: clamp(2rem, 4vw, 2.5rem);
      text-align: center;
      margin-bottom: rem;
      color: var(--primary-color);
      position: relative;
    }

    .section-title::after {
      content: '';
      position: absolute;
      bottom: -10px;
      left: 50%;
      transform: translateX(-50%);
      width: 80px;
      height: 4px;
      background: var(--gradient-primary);
      border-radius: 2px;
    }

    /* Project Gallery with Flip Cards */
    .project-gallery {
      display: grid;
      grid-template-columns: repeat(auto-fit, minmax(280px, 1fr));
      gap: 2rem;
      padding: 2rem 0;
      justify-content: center;
      max-width: 1500px;
      margin: 0 auto;
      margin-bottom: 50px;
    }

    .project-card {
      perspective: 1000px;
      height: 420px;
      cursor: pointer;
      transition: var(--transition);
    }

    .project-card:nth-child(odd) {
      transform: rotate(-2deg);
    }

    .project-card:nth-child(even) {
      transform: rotate(2deg);
    }

    .project-card:nth-child(3n) {
      transform: rotate(1deg);
    }

    .project-card:hover {
      transform: rotate(0deg) scale(1.02);
      z-index: 10;
    }

    .card-inner {
      position: relative;
      width: 100%;
      height: 105%;
      text-align: center;
      transition: transform 0.8s cubic-bezier(0.4, 0, 0.2, 1);
      transform-style: preserve-3d;
      border-radius: 15px;
      box-shadow: var(--shadow-lg);
      
    }

    .project-card:hover .card-inner {
      transform: rotateY(180deg);
    }

    .card-front, .card-back {
      position: absolute;
      width: 100%;
      height: 100%;
      backface-visibility: hidden;
      border-radius: 15px;
      overflow: hidden;
      display: flex;
      flex-direction: column;
    
     
    }

    .card-front {
      background: white;
      border: 1px solid var(--border-color);
    }

    .card-back {
      background: var(--gradient-primary);
      color: white;
      transform: rotateY(180deg);
      padding: 2rem;
      justify-content: center;
      align-items: center;
      text-align: center;
    }

    .card-image {
  width: 92%;
  height: 325px;
  object-fit: cover;
  transition: var(--transition);
  display: block;       /* para que margin funcione */
  margin: 0 auto;       /* centrado horizontal */
}


    .card-content {
      padding: 1.5rem;
      flex: 1;
      display: flex;
      flex-direction: column;
      justify-content: center;
    }

    .card-title {
      font-size: 1.2rem;
      font-weight: 600;
      color: var(--primary-color);
      margin-bottom: 0.5rem;
    }

    .card-tech {
      font-size: 0.9rem;
      color: var(--text-light);
      font-style: italic;
    }

    .card-back h3 {
      font-size: 1.4rem;
      margin-bottom: 1rem;
      color: white;
    }

    .card-back p {
      font-size: 1rem;
      line-height: 1.6;
      margin-bottom: 1.5rem;
      opacity: 0.95;
    }

    .card-back-links {
      display: flex;
      gap: 1rem;
      justify-content: center;
      flex-wrap: wrap;
    }

    .card-link {
      display: inline-flex;
      align-items: center;
      gap: 0.5rem;
      background: rgba(255, 255, 255, 0.2);
      color: white;
      text-decoration: none;
      padding: 0.8rem 1.2rem;
      border-radius: 25px;
      font-weight: 500;
      transition: var(--transition);
      backdrop-filter: blur(10px);
      border: 1px solid rgba(255, 255, 255, 0.3);
    }

    .card-link:hover {
      background: rgba(255, 255, 255, 0.3);
      transform: translateY(-2px);
    }

    .tech-tags {
      display: flex;
      flex-wrap: wrap;
      gap: 0.5rem;
      justify-content: center;
      margin-top: 1rem;
    }

    .tech-tag {
      background: rgba(255, 255, 255, 0.2);
      color: white;
      padding: 0.3rem 0.8rem;
      border-radius: 15px;
      font-size: 0.8rem;
      font-weight: 500;
    }

    /* Footer 
    footer {
      background: var(--primary-color);
      color: white;
      padding: 3rem 0;
    }

    .footer-content {
      display: flex;
      justify-content: space-between;
      align-items: center;
      flex-wrap: wrap;
      gap: 2rem;
    } */

    .download-btn {
      display: inline-flex;
      align-items: center;
      gap: 0.5rem;
      background: var(--gradient-secondary);
      color: white;
      text-decoration: none;
      padding: 1rem 2rem;
      border-radius: 50px;
      font-weight: 600;
      transition: var(--transition);
      box-shadow: var(--shadow);
    }

    .download-btn:hover {
      transform: translateY(-3px);
      box-shadow: 0 10px 25px rgba(0,0,0,0.2);
    }

    /* Social Links */

    /* Instructions */
    .instructions {
      text-align: center;
      margin-bottom: 2rem;
      padding: 1rem;
      background: rgba(255, 255, 255, 0.9);
      border-radius: 15px;
      box-shadow: var(--shadow);
    }

    .instructions p {
      color: var(--text-light);
      font-size: 1rem;
      margin: 0;
    }

    .instructions i {
      color: var(--secondary-color);
      margin: 0 0.5rem;
    }

    /* Animations */
    .fade-in {
      opacity: 0;
      transform: translateY(30px);
      animation: fadeInUp 0.8s ease-out forwards;
    }

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

    /* Responsive */
    @media (max-width: 768px) {
      .container {
        padding: 0 15px;
      }

      .project-gallery {
        grid-template-columns: repeat(auto-fit, minmax(250px, 1fr));
        gap: 1.5rem;
        padding: 1rem 0;
      }

      .project-card {
        height: 300px;
      }

      .card-back {
        padding: 1.5rem;
      }

      .card-back-links {
        flex-direction: column;
        gap: 0.8rem;
      }

      .footer-content {
        flex-direction: column;
        text-align: center;
        gap: 2rem;
      }

      .social-links {
        order: -1;
      }
    }

    @media (max-width: 480px) {
      .hero {
        padding: 3rem 0;
      }

      .section {
        padding: 3rem 0;
      }

      .project-gallery {
        grid-template-columns: 1fr;
        gap: 1.5rem;
      }

      .project-card {
        height: 280px;
      }
    }