/* ========================
   CSS Custom Properties
======================== */
:root {
    --primary-blue: #38bdf8;
    --primary-blue-hover: #0ea5e9;
    --dark-bg: #0f172a;
    --dark-secondary: #1e293b;
    --light-bg: #f8fafc;
    --light-secondary: #e2e8f0;
    --text-dark: #1e293b;
    --text-light: #475569;
    --white: #ffffff;
    --shadow-light: 0 4px 12px rgba(0, 0, 0, 0.05);
    --shadow-medium: 0 8px 20px rgba(0, 0, 0, 0.15);
    --border-radius: 1rem;
    --transition: all 0.3s ease;
    --react-blue: #61DAFB;
    --success-green: #10b981;
    --warning-orange: #f59e0b;
  }
  
  /* ========================
     Base Styles & Reset
  ======================== */
  * {
    box-sizing: border-box;
  }
  
  body {
    margin: 0;
    font-family: 'Segoe UI', Tahoma, Geneva, Verdana, sans-serif;
    background-color: var(--light-bg);
    color: var(--text-dark);
    line-height: 1.6;
    position: relative;
    z-index: 1;
  }
  
  /* ========================
     Accessibility & Motion
  ======================== */
  @media (prefers-reduced-motion: reduce) {
    *, *::before, *::after {
      animation-duration: 0.01ms !important;
      animation-iteration-count: 1 !important;
      transition-duration: 0.01ms !important;
    }
  }
  
  /* Focus styles for accessibility */
  *:focus {
    outline: 2px solid var(--primary-blue);
    outline-offset: 2px;
  }
  
  /* ========================
     Background Watermark
  ======================== */
  body::before {
    content: "";
    position: fixed;
    top: 50%;
    left: 50%;
    width: min(600px, 80vw);
    height: min(600px, 80vw);
    background-image: url('STS.png');
    background-repeat: no-repeat;
    background-size: contain;
    background-position: center;
    opacity: 0.05;
    transform: translate(-50%, -50%);
    z-index: 0;
    pointer-events: none;
    animation: spinLogo 120s linear infinite, pulse 10s ease-in-out infinite;
  }
  
  @keyframes spinLogo {
    0% { transform: translate(-50%, -50%) rotate(0deg); }
    100% { transform: translate(-50%, -50%) rotate(360deg); }
  }
  
  @keyframes pulse {
    0%, 100% { opacity: 0.04; }
    50% { opacity: 0.07; }
  }
  
  /* ========================
     Sticky Navigation
  ======================== */
  .sticky-nav {
    position: fixed;
    top: 0;
    left: 0;
    width: 100%;
    background: rgba(15, 23, 42, 0.95);
    display: flex;
    align-items: center;
    justify-content: space-between;
    padding: 0.75rem 1.5rem;
    z-index: 999;
    box-shadow: var(--shadow-medium);
    backdrop-filter: blur(10px);
    transition: var(--transition);
  }
  
  .nav-brand {
    display: flex;
    align-items: center;
    color: var(--white);
    font-weight: 600;
    font-size: 1rem;
    letter-spacing: 0.5px;
  }
  
  .nav-logo {
    width: 40px;
    height: 40px;
    margin-right: 0.75rem;
    background: var(--primary-blue);
    border-radius: 50%;
    display: flex;
    align-items: center;
    justify-content: center;
    font-weight: bold;
    color: var(--dark-bg);
  }
  
  .nav-menu {
    display: none;
    gap: 2rem;
  }
  
  .nav-menu a {
    color: var(--white);
    text-decoration: none;
    font-weight: 500;
    transition: var(--transition);
    padding: 0.5rem 0;
    border-bottom: 2px solid transparent;
  }
  
  .nav-menu a:hover {
    color: var(--primary-blue);
    border-bottom-color: var(--primary-blue);
  }
  
  /* ========================
     Hero Section
  ======================== */
  .hero {
    min-height: 100vh;
    display: flex;
    align-items: center;
    justify-content: center;
    padding: 6rem 2rem 4rem;
    background: linear-gradient(135deg, var(--dark-bg) 0%, var(--dark-secondary) 100%);
    color: var(--white);
    position: relative;
    overflow: hidden;
  }
  
  .hero::before {
    content: '';
    position: absolute;
    top: 0;
    left: 0;
    right: 0;
    bottom: 0;
    background: 
      radial-gradient(circle at 20% 50%, rgba(56, 189, 248, 0.1) 0%, transparent 50%),
      radial-gradient(circle at 80% 20%, rgba(56, 189, 248, 0.1) 0%, transparent 50%);
    z-index: 1;
  }
  
  .hero-container {
    display: grid;
    grid-template-columns: 1fr;
    gap: 3rem;
    max-width: 1200px;
    margin: 0 auto;
    position: relative;
    z-index: 2;
    text-align: center;
  }
  
  .hero-content h1 {
    font-size: clamp(2.5rem, 5vw, 3.5rem);
    margin-bottom: 1rem;
    font-weight: 700;
    background: linear-gradient(45deg, var(--white), var(--primary-blue));
    -webkit-background-clip: text;
    -webkit-text-fill-color: transparent;
    background-clip: text;
  }
  
  .hero-content p {
    font-size: clamp(1rem, 2.5vw, 1.25rem);
    max-width: 600px;
    margin: 0 auto 2rem auto;
    opacity: 0.9;
    line-height: 1.7;
  }
  
  .hero-image {
    display: flex;
    justify-content: center;
    margin-top: 2rem;
  }
  
  .profile-photo {
    width: min(300px, 80vw);
    height: min(300px, 80vw);
    object-fit: cover;
    border-radius: 50%;
    border: 4px solid var(--primary-blue);
    box-shadow: var(--shadow-medium);
    transition: var(--transition);
    animation: float 3s ease-in-out infinite;
  }
  
  .profile-photo:hover {
    transform: scale(1.05);
    box-shadow: 0 12px 30px rgba(56, 189, 248, 0.3);
  }
  
  @keyframes float {
    0%, 100% { transform: translateY(0px); }
    50% { transform: translateY(-10px); }
  }
  
  /* ========================
     Buttons
  ======================== */
  .btn {
    display: inline-block;
    padding: 1rem 2rem;
    background: var(--primary-blue);
    color: var(--dark-bg);
    font-weight: 600;
    text-decoration: none;
    border-radius: var(--border-radius);
    transition: var(--transition);
    box-shadow: var(--shadow-light);
    border: none;
    cursor: pointer;
    font-size: 1rem;
  }
  
  .btn:hover {
    background: var(--primary-blue-hover);
    transform: translateY(-2px);
    box-shadow: var(--shadow-medium);
  }
  
  .btn-secondary {
    background: transparent;
    color: var(--primary-blue);
    border: 2px solid var(--primary-blue);
  }
  
  .btn-secondary:hover {
    background: var(--primary-blue);
    color: var(--dark-bg);
  }
  
  .btn-disabled {
    background: var(--light-secondary);
    color: var(--text-light);
    cursor: not-allowed;
    opacity: 0.6;
  }
  
  .btn-disabled:hover {
    transform: none;
    background: var(--light-secondary);
  }
  
  /* ========================
     Section Layouts
  ======================== */
  .section {
    padding: 4rem 2rem;
    max-width: 1200px;
    margin: 0 auto;
    opacity: 0;
    transform: translateY(50px);
    transition: all 0.8s ease;
  }
  
  .section.visible {
    opacity: 1;
    transform: translateY(0);
  }
  
  .section h2 {
    font-size: clamp(2rem, 4vw, 2.5rem);
    margin-bottom: 1rem;
    text-align: center;
    color: var(--text-dark);
  }
  
  .section p {
    max-width: 800px;
    margin: 0 auto 2rem auto;
    text-align: center;
    font-size: 1.1rem;
    color: var(--text-light);
  }
  
  /* ========================
     Apps Section - NEW!
  ======================== */
  .apps-showcase {
    background: linear-gradient(135deg, #f8fafc 0%, #e2e8f0 100%);
    border-radius: var(--border-radius);
    margin: 4rem auto;
    box-shadow: var(--shadow-light);
  }
  
  .app-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(350px, 1fr));
    gap: 2rem;
    margin-top: 3rem;
  }
  
  .app-card {
    background: var(--white);
    border-radius: var(--border-radius);
    box-shadow: var(--shadow-light);
    overflow: hidden;
    transition: var(--transition);
    border: 2px solid transparent;
    position: relative;
  }
  
  .app-card:hover {
    transform: translateY(-5px);
    box-shadow: var(--shadow-medium);
    border-color: var(--primary-blue);
  }
  
  .app-card.featured {
    border-color: var(--react-blue);
    background: linear-gradient(135deg, #ffffff 0%, #f0f9ff 100%);
  }
  
  .app-card.featured::before {
    content: '✨ Featured';
    position: absolute;
    top: 1rem;
    right: 1rem;
    background: var(--react-blue);
    color: var(--white);
    padding: 0.25rem 0.75rem;
    border-radius: 1rem;
    font-size: 0.8rem;
    font-weight: 600;
    z-index: 2;
  }
  
  .app-card.coming-soon {
    opacity: 0.8;
    background: linear-gradient(135deg, #f8fafc 0%, #f1f5f9 100%);
  }
  
  .app-header {
    display: flex;
    align-items: center;
    padding: 2rem 2rem 1rem 2rem;
    gap: 1rem;
  }
  
  .app-logo {
    width: 60px;
    height: 60px;
    border-radius: 12px;
    box-shadow: var(--shadow-light);
    object-fit: cover;
  }
  
  .coming-soon-logo {
    width: 60px;
    height: 60px;
    border-radius: 12px;
    background: var(--light-secondary);
    display: flex;
    align-items: center;
    justify-content: center;
    font-size: 24px;
  }
  
  .app-info h3 {
    margin: 0 0 0.25rem 0;
    font-size: 1.5rem;
    color: var(--text-dark);
  }
  
  .app-subtitle {
    margin: 0;
    color: var(--text-light);
    font-size: 0.9rem;
    font-weight: 500;
  }
  
  .app-description {
    padding: 0 2rem 1rem 2rem;
  }
  
  .app-description p {
    margin: 0 0 1.5rem 0;
    text-align: left;
    font-size: 1rem;
    line-height: 1.6;
  }
  
  .app-features {
    display: flex;
    flex-wrap: wrap;
    gap: 0.5rem;
    margin-bottom: 1.5rem;
  }
  
  .feature-tag {
    background: var(--light-secondary);
    color: var(--text-dark);
    padding: 0.25rem 0.75rem;
    border-radius: 1rem;
    font-size: 0.8rem;
    font-weight: 500;
  }
  
  .app-tech {
    font-size: 0.9rem;
    color: var(--text-light);
  }
  
  .tech-badge {
    display: inline-block;
    background: var(--primary-blue);
    color: var(--white);
    padding: 0.25rem 0.5rem;
    border-radius: 0.5rem;
    font-size: 0.8rem;
    font-weight: 500;
    margin: 0.25rem 0.25rem 0 0;
  }
  
  .app-actions {
    padding: 1rem 2rem 2rem 2rem;
    display: flex;
    gap: 1rem;
    flex-wrap: wrap;
  }
  
  .app-btn {
    background: var(--react-blue);
    color: var(--dark-bg);
  }
  
  .app-btn:hover {
    background: #4fa8c5;
  }
  
  /* ========================
     Card Grid System
  ======================== */
  .card-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(280px, 1fr));
    gap: 2rem;
    margin-top: 3rem;
  }
  
  .card {
    background: var(--white);
    padding: 2rem;
    border-radius: var(--border-radius);
    box-shadow: var(--shadow-light);
    transition: var(--transition);
    border: 1px solid transparent;
    position: relative;
    overflow: hidden;
  }
  
  .card::before {
    content: '';
    position: absolute;
    top: 0;
    left: 0;
    right: 0;
    height: 4px;
    background: linear-gradient(90deg, var(--primary-blue), var(--primary-blue-hover));
    transform: scaleX(0);
    transition: var(--transition);
  }
  
  .card:hover {
    transform: translateY(-8px);
    box-shadow: var(--shadow-medium);
    border-color: var(--primary-blue);
  }
  
  .card:hover::before {
    transform: scaleX(1);
  }
  
  .card h3 {
    color: var(--text-dark);
    margin-bottom: 1rem;
    font-size: 1.25rem;
  }
  
  .card p {
    color: var(--text-light);
    margin: 0;
    text-align: left;
    font-size: 1rem;
    line-height: 1.6;
  }
  
  /* ========================
     Specific Sections
  ======================== */
  .about {
    background: var(--white);
    border-radius: var(--border-radius);
    margin: 2rem auto;
    box-shadow: var(--shadow-light);
  }
  
  .highlight {
    background: linear-gradient(135deg, var(--primary-blue) 0%, var(--primary-blue-hover) 100%);
    color: var(--white);
    border-radius: var(--border-radius);
    margin: 4rem auto;
  }
  
  .highlight h2 {
    color: var(--white);
  }
  
  .highlight p {
    color: rgba(255, 255, 255, 0.9);
  }
  
  .custom-list {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(250px, 1fr));
    gap: 1rem;
    margin: 2rem 0;
  }
  
  .custom-list p {
    background: rgba(255, 255, 255, 0.1);
    padding: 1rem;
    border-radius: 0.5rem;
    margin: 0;
    font-size: 1rem;
    backdrop-filter: blur(5px);
  }
  
  .massage {
    background: var(--white);
    border-radius: var(--border-radius);
    margin: 2rem auto;
    box-shadow: var(--shadow-light);
    text-align: center;
  }
  
  .massage-img {
    width: 100%;
    max-width: 300px;
    border-radius: var(--border-radius);
    margin: 1.5rem auto;
    display: block;
    box-shadow: var(--shadow-light);
  }
  
  .credentials {
    font-weight: 600;
    color: var(--primary-blue);
    font-size: 1.1rem;
  }
  
  /* ========================
     Contact Section
  ======================== */
  .contact {
    background: var(--dark-bg);
    color: var(--white);
    border-radius: var(--border-radius);
    margin: 4rem auto 2rem auto;
    text-align: center;
  }
  
  .contact h2 {
    color: var(--white);
  }
  
  .contact p {
    text-align: center;
    max-width: 600px;
    margin: 0 auto 1rem auto;
  }
  
  .contact a {
    color: var(--primary-blue);
    text-decoration: none;
    transition: var(--transition);
  }
  
  .contact a:hover {
    color: var(--primary-blue-hover);
    text-decoration: underline;
  }
  
  .contact .btn {
    background: var(--primary-blue) !important;
    color: var(--dark-bg) !important;
    border: 2px solid var(--primary-blue) !important;
    font-weight: 600;
    text-decoration: none;
    padding: 1rem 2rem;
    border-radius: var(--border-radius);
    display: inline-block;
    transition: var(--transition);
    margin: 1rem auto;
    text-align: center;
  }
  
  .contact .btn:hover {
    background: var(--primary-blue-hover) !important;
    color: var(--white) !important;
    transform: translateY(-2px);
    box-shadow: var(--shadow-medium);
  }
  
  /* ========================
     Footer
  ======================== */
  footer {
    text-align: center;
    padding: 2rem;
    background: var(--light-secondary);
    font-size: 0.9rem;
    color: var(--text-light);
    margin-top: 2rem;
  }
  
  /* ========================
     Responsive Design
  ======================== */
  @media (min-width: 768px) {
    .nav-menu {
      display: flex;
    }
  
    .hero-container {
      grid-template-columns: 1fr 1fr;
      text-align: left;
      align-items: center;
    }
  
    .hero-content {
      order: 1;
    }
  
    .hero-image {
      order: 2;
      margin-top: 0;
    }
  
    .section {
      padding: 5rem 2rem;
    }
  
    .card-grid {
      grid-template-columns: repeat(auto-fit, minmax(300px, 1fr));
      gap: 2.5rem;
    }
  
    .app-grid {
      grid-template-columns: repeat(auto-fit, minmax(400px, 1fr));
    }
  
    .app-actions {
      flex-direction: row;
    }
  }
  
  @media (min-width: 1024px) {
    .sticky-nav {
      padding: 1rem 2rem;
    }
  
    .hero {
      padding: 8rem 2rem 6rem;
    }
  
    .card-grid {
      grid-template-columns: repeat(3, 1fr);
    }
  
    .app-grid {
      grid-template-columns: repeat(2, 1fr);
    }
  }
  
  /* ========================
     Skills Animation
  ======================== */
  .skill-badge {
    display: inline-block;
    background: var(--primary-blue);
    color: var(--white);
    padding: 0.5rem 1rem;
    border-radius: 2rem;
    font-size: 0.9rem;
    font-weight: 500;
    margin: 0.25rem;
    transition: var(--transition);
  }
  
  .skill-badge:hover {
    background: var(--primary-blue-hover);
    transform: scale(1.05);
  }
  
  /* ========================
     Loading Animation
  ======================== */
  .loading {
    opacity: 0;
    animation: fadeInUp 0.8s ease forwards;
  }
  
  @keyframes fadeInUp {
    from {
      opacity: 0;
      transform: translateY(30px);
    }
    to {
      opacity: 1;
      transform: translateY(0);
    }
  }