/* CSS Custom Properties */
:root {
  --primary-color: #2563eb;
  --primary-dark: #1d4ed8;
  --secondary-color: #64748b;
  --accent-color: #0ea5e9;
  --background-color: #ffffff;
  --surface-color: #f8fafc;
  --border-color: #e2e8f0;
  --text-primary: #0f172a;
  --text-secondary: #475569;
  --text-muted: #64748b;
  --shadow-sm: 0 1px 2px 0 rgb(0 0 0 / 0.05);
  --shadow-md: 0 4px 6px -1px rgb(0 0 0 / 0.1), 0 2px 4px -2px rgb(0 0 0 / 0.1);
  --shadow-lg: 0 10px 15px -3px rgb(0 0 0 / 0.1), 0 4px 6px -4px rgb(0 0 0 / 0.1);
  --shadow-xl: 0 20px 25px -5px rgb(0 0 0 / 0.1), 0 8px 10px -6px rgb(0 0 0 / 0.1);
  --radius-sm: 0.375rem;
  --radius-md: 0.5rem;
  --radius-lg: 0.75rem;
  --radius-xl: 1rem;
  --font-family: 'Inter', -apple-system, BlinkMacSystemFont, 'Segoe UI', sans-serif;
  --transition: all 0.3s cubic-bezier(0.4, 0, 0.2, 1);
}

/* Reset and Base Styles */
*,
*::before,
*::after {
  box-sizing: border-box;
  margin: 0;
  padding: 0;
}

html {
  scroll-behavior: smooth;
  font-size: 16px;
}

body {
  font-family: var(--font-family);
  line-height: 1.6;
  color: var(--text-primary);
  background-color: var(--background-color);
  -webkit-font-smoothing: antialiased;
  -moz-osx-font-smoothing: grayscale;
}

/* Typography */
h1, h2, h3, h4, h5, h6 {
  font-weight: 600;
  line-height: 1.25;
  letter-spacing: -0.025em;
}

.hero-title {
  font-size: clamp(2.5rem, 5vw, 4rem);
  font-weight: 700;
  color: var(--text-primary);
  margin-bottom: 1.5rem;
}

.section-title {
  font-size: 2.5rem;
  font-weight: 700;
  color: var(--text-primary);
  margin-bottom: 1rem;
}

.card-title {
  font-size: 1.5rem;
  font-weight: 600;
  color: var(--text-primary);
  margin-bottom: 1rem;
}

/* Layout Containers */
.container {
  width: 100%;
  max-width: 1200px;
  margin: 0 auto;
  padding: 0 1.5rem;
}

/* Header and Navigation */
.header {
  position: fixed;
  top: 0;
  left: 0;
  right: 0;
  background: rgba(255, 255, 255, 0.95);
  backdrop-filter: blur(10px);
  border-bottom: 1px solid var(--border-color);
  z-index: 1000;
  transition: var(--transition);
}

.nav-container {
  max-width: 1200px;
  margin: 0 auto;
  padding: 0 1.5rem;
  display: flex;
  align-items: center;
  justify-content: space-between;
  height: 4rem;
}

.nav-brand {
  display: flex;
  flex-direction: column;
}

.brand-title {
  font-size: 1.5rem;
  font-weight: 700;
  color: var(--primary-color);
  line-height: 1;
}

.brand-subtitle {
  font-size: 0.75rem;
  font-weight: 500;
  color: var(--text-muted);
  text-transform: uppercase;
  letter-spacing: 0.1em;
}

.nav-menu {
  display: flex;
  list-style: none;
  gap: 2rem;
}

.nav-link {
  color: var(--text-secondary);
  text-decoration: none;
  font-weight: 500;
  font-size: 0.9rem;
  transition: var(--transition);
  position: relative;
}

.nav-link:hover {
  color: var(--primary-color);
}

.nav-link::after {
  content: '';
  position: absolute;
  bottom: -0.5rem;
  left: 0;
  width: 0;
  height: 2px;
  background-color: var(--primary-color);
  transition: var(--transition);
}

.nav-link:hover::after {
  width: 100%;
}

/* Main Content */
.main {
  margin-top: 4rem;
}

/* Hero Section */
.hero {
  background: linear-gradient(135deg, var(--surface-color) 0%, #ffffff 100%);
  padding: 6rem 0;
  position: relative;
  overflow: hidden;
}

.hero::before {
  content: '';
  position: absolute;
  top: 0;
  left: 0;
  right: 0;
  bottom: 0;
  background: radial-gradient(circle at 30% 20%, rgba(37, 99, 235, 0.1) 0%, transparent 50%),
              radial-gradient(circle at 70% 80%, rgba(14, 165, 233, 0.1) 0%, transparent 50%);
  pointer-events: none;
}

.hero-container {
  max-width: 1200px;
  margin: 0 auto;
  padding: 0 1.5rem;
  position: relative;
  z-index: 1;
}

.hero-content {
  max-width: 800px;
  text-align: center;
  margin: 0 auto;
}

.hero-description {
  font-size: 1.25rem;
  color: var(--text-secondary);
  margin-bottom: 3rem;
  line-height: 1.7;
}

.hero-stats {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(150px, 1fr));
  gap: 2rem;
  margin-top: 4rem;
}

.stat {
  text-align: center;
  padding: 1.5rem;
  background: var(--background-color);
  border-radius: var(--radius-lg);
  box-shadow: var(--shadow-md);
  transition: var(--transition);
}

.stat:hover {
  transform: translateY(-4px);
  box-shadow: var(--shadow-lg);
}

.stat-number {
  display: block;
  font-size: 2rem;
  font-weight: 700;
  color: var(--primary-color);
  margin-bottom: 0.5rem;
}

.stat-label {
  font-size: 0.9rem;
  color: var(--text-muted);
  text-transform: uppercase;
  letter-spacing: 0.1em;
}

/* Core Elements Section */
.core-elements {
  padding: 6rem 0;
  background: var(--background-color);
}

.section-header {
  text-align: center;
  margin-bottom: 4rem;
  max-width: 600px;
  margin-left: auto;
  margin-right: auto;
}

.section-description {
  font-size: 1.125rem;
  color: var(--text-secondary);
  line-height: 1.7;
}

.elements-grid {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(350px, 1fr));
  gap: 2rem;
  margin-top: 4rem;
}

.element-card {
  background: var(--background-color);
  border: 1px solid var(--border-color);
  border-radius: var(--radius-xl);
  padding: 2rem;
  transition: var(--transition);
  position: relative;
  overflow: hidden;
}

.element-card::before {
  content: '';
  position: absolute;
  top: 0;
  left: 0;
  width: 100%;
  height: 4px;
  background: linear-gradient(90deg, var(--primary-color), var(--accent-color));
  transform: scaleX(0);
  transform-origin: left;
  transition: var(--transition);
}

.element-card:hover {
  transform: translateY(-8px);
  box-shadow: var(--shadow-xl);
  border-color: var(--primary-color);
}

.element-card:hover::before {
  transform: scaleX(1);
}

.card-header {
  margin-bottom: 1.5rem;
}

.card-number {
  display: inline-block;
  width: 3rem;
  height: 3rem;
  background: linear-gradient(135deg, var(--primary-color), var(--accent-color));
  color: white;
  border-radius: 50%;
  display: flex;
  align-items: center;
  justify-content: center;
  font-weight: 700;
  font-size: 1.125rem;
  margin-bottom: 1rem;
}

.card-description {
  color: var(--text-secondary);
  margin-bottom: 1.5rem;
  line-height: 1.7;
}

.card-features {
  list-style: none;
}

.card-features li {
  color: var(--text-muted);
  margin-bottom: 0.5rem;
  padding-left: 1.5rem;
  position: relative;
  font-size: 0.9rem;
}

.card-features li::before {
  content: '✓';
  position: absolute;
  left: 0;
  color: var(--primary-color);
  font-weight: 700;
}

/* About Section */
.about {
  padding: 6rem 0;
  background: var(--surface-color);
}

.about-content {
  display: grid;
  grid-template-columns: 2fr 1fr;
  gap: 4rem;
  align-items: start;
}

.about-title {
  font-size: 2rem;
  font-weight: 700;
  color: var(--text-primary);
  margin-bottom: 1.5rem;
}

.about-description {
  color: var(--text-secondary);
  margin-bottom: 1.5rem;
  line-height: 1.7;
}

.about-author {
  background: var(--background-color);
  padding: 2rem;
  border-radius: var(--radius-xl);
  box-shadow: var(--shadow-md);
}

.author-title {
  font-size: 1.5rem;
  font-weight: 600;
  color: var(--text-primary);
  margin-bottom: 0.5rem;
}

.author-role {
  color: var(--primary-color);
  font-weight: 500;
  margin-bottom: 1rem;
  font-size: 0.9rem;
  text-transform: uppercase;
  letter-spacing: 0.1em;
}

.author-description {
  color: var(--text-secondary);
  line-height: 1.6;
  font-size: 0.9rem;
  margin-bottom: 1.5rem;
}

.author-credentials {
  margin-top: 1.5rem;
}

.credentials-text {
  color: var(--text-secondary);
  font-size: 0.85rem;
  line-height: 1.5;
  margin-bottom: 0.75rem;
}

.credentials-text strong {
  color: var(--text-primary);
  font-weight: 600;
}

.linkedin-link {
  display: inline-block;
  color: var(--primary-color);
  text-decoration: none;
  font-weight: 500;
  font-size: 0.9rem;
  margin-top: 0.75rem;
  padding: 0.5rem 1rem;
  border: 1px solid var(--primary-color);
  border-radius: var(--radius-sm);
  transition: var(--transition);
}

.linkedin-link:hover {
  background-color: var(--primary-color);
  color: white;
  transform: translateY(-2px);
}

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

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

.footer-title {
  font-size: 1.5rem;
  font-weight: 700;
  margin-bottom: 0.5rem;
}

.footer-description {
  color: rgba(255, 255, 255, 0.7);
  font-size: 0.9rem;
}

.footer-text {
  color: rgba(255, 255, 255, 0.7);
  font-size: 0.9rem;
}

/* Responsive Design */
@media (max-width: 768px) {
  .nav-menu {
    display: none;
  }

  .hero {
    padding: 4rem 0;
  }

  .hero-title {
    font-size: 2.5rem;
  }

  .hero-stats {
    grid-template-columns: 1fr;
    gap: 1rem;
  }

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

  .about-content {
    grid-template-columns: 1fr;
    gap: 2rem;
  }

  .footer-content {
    flex-direction: column;
    gap: 1rem;
    text-align: center;
  }

  .section-title {
    font-size: 2rem;
  }

  .container {
    padding: 0 1rem;
  }
}

@media (max-width: 480px) {
  .hero-title {
    font-size: 2rem;
  }

  .hero-description {
    font-size: 1rem;
  }

  .element-card {
    padding: 1.5rem;
  }

  .about-author {
    padding: 1.5rem;
  }
}

/* Animation Classes */
.fade-in {
  opacity: 0;
  transform: translateY(30px);
  transition: opacity 0.6s ease-out, transform 0.6s ease-out;
}

.fade-in.visible {
  opacity: 1;
  transform: translateY(0);
}

.slide-in-left {
  opacity: 0;
  transform: translateX(-50px);
  transition: opacity 0.6s ease-out, transform 0.6s ease-out;
}

.slide-in-left.visible {
  opacity: 1;
  transform: translateX(0);
}

.slide-in-right {
  opacity: 0;
  transform: translateX(50px);
  transition: opacity 0.6s ease-out, transform 0.6s ease-out;
}

.slide-in-right.visible {
  opacity: 1;
  transform: translateX(0);
}

/* Focus and Accessibility */
.nav-link:focus,
.element-card:focus {
  outline: 2px solid var(--primary-color);
  outline-offset: 2px;
}

/* Print Styles */
@media print {
  .header,
  .footer {
    display: none;
  }

  .main {
    margin-top: 0;
  }

  .element-card {
    break-inside: avoid;
    margin-bottom: 1rem;
  }
}