/* Modern Design System */
:root {
  /* Colors */
  --primary: #0a0a0a;
  --primary-light: #1a1a1a;
  --accent: #6366f1;
  --accent-light: #a5b4fc;
  --accent-hover: #4f46e5;
  --text-primary: #0f172a;
  --text-secondary: #64748b;
  --text-muted: #94a3b8;
  --surface: #ffffff;
  --surface-alt: #f8fafc;
  --surface-hover: #f1f5f9;
  --border: #e2e8f0;
  --border-light: #f1f5f9;
  --shadow-sm: 0 1px 2px 0 rgb(0 0 0 / 0.05);
  --shadow: 0 4px 6px -1px rgb(0 0 0 / 0.1);
  --shadow-lg: 0 10px 15px -3px rgb(0 0 0 / 0.1);
  --shadow-xl: 0 20px 25px -5px rgb(0 0 0 / 0.1);
  
  /* Gradients */
  --gradient-primary: linear-gradient(135deg, #667eea 0%, #764ba2 100%);
  --gradient-accent: linear-gradient(135deg, #6366f1 0%, #8b5cf6 100%);
  --gradient-surface: linear-gradient(135deg, #f8fafc 0%, #ffffff 100%);
  
  /* Spacing */
  --space-xs: 0.5rem;
  --space-sm: 1rem;
  --space-md: 1.5rem;
  --space-lg: 2rem;
  --space-xl: 3rem;
  --space-2xl: 4rem;
  --space-3xl: 6rem;
  
  /* Typography */
  --font-sans: 'Inter', -apple-system, BlinkMacSystemFont, 'Segoe 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;
  --font-size-5xl: 3rem;
  --font-size-6xl: 3.75rem;
  
  /* Border Radius */
  --radius-sm: 0.375rem;
  --radius: 0.5rem;
  --radius-lg: 0.75rem;
  --radius-xl: 1rem;
  --radius-2xl: 1.5rem;
  --radius-full: 9999px;
  
  /* Transitions */
  --transition-fast: 150ms ease;
  --transition: 250ms ease;
  --transition-slow: 350ms ease;
}

/* Reset & Base Styles */
*, *::before, *::after {
  box-sizing: border-box;
}

* {
  margin: 0;
  padding: 0;
}

html {
  scroll-behavior: smooth;
}

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

img, picture, video, canvas, svg {
  display: block;
  max-width: 100%;
}

input, button, textarea, select {
  font: inherit;
}

p, h1, h2, h3, h4, h5, h6 {
  overflow-wrap: break-word;
}

/* Utility Classes */
.container {
  max-width: 1200px;
  margin: 0 auto;
  padding: 0 var(--space-lg);
}

.text-center { text-align: center; }
.font-medium { font-weight: 500; }
.font-semibold { font-weight: 600; }
.font-bold { font-weight: 700; }

/* Header */
.header {
  position: fixed;
  top: 0;
  left: 0;
  right: 0;
  background: rgba(248, 250, 252, 0.8);
  backdrop-filter: blur(20px);
  border-bottom: 1px solid var(--border);
  z-index: 1000;
  transition: all var(--transition);
}

.nav {
  display: flex;
  justify-content: space-between;
  align-items: center;
  padding: var(--space-sm) var(--space-lg);
  max-width: 1200px;
  margin: 0 auto;
}

.logo {
  font-weight: 800;
  font-size: var(--font-size-2xl);
  background: var(--gradient-primary);
  -webkit-background-clip: text;
  -webkit-text-fill-color: transparent;
  background-clip: text;
  text-decoration: none;
}

.nav-links {
  display: flex;
  gap: var(--space-xl);
  list-style: none;
  align-items: center;
}

.nav-links a {
  text-decoration: none;
  color: var(--text-secondary);
  font-weight: 500;
  font-size: var(--font-size-sm);
  position: relative;
  transition: color var(--transition);
  padding: var(--space-xs) 0;
}

.nav-links a:hover {
  color: var(--accent);
}

.nav-links a::after {
  content: '';
  position: absolute;
  bottom: -2px;
  left: 0;
  width: 0;
  height: 2px;
  background: var(--gradient-accent);
  transition: width var(--transition);
}

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

/* Mobile Navigation */
.mobile-menu-toggle {
  display: none;
  background: none;
  border: none;
  color: var(--text-primary);
  font-size: var(--font-size-xl);
  cursor: pointer;
  padding: var(--space-xs);
}

.mobile-nav {
  position: fixed;
  top: 0;
  left: 0;
  width: 100%;
  height: 100vh;
  background: rgba(10, 10, 10, 0.95);
  backdrop-filter: blur(20px);
  z-index: 999;
  display: flex;
  align-items: center;
  justify-content: center;
  opacity: 0;
  visibility: hidden;
  transition: all var(--transition-slow);
}

.mobile-nav.active {
  opacity: 1;
  visibility: visible;
}

.mobile-nav-content {
  text-align: center;
  position: relative;
}

.mobile-close {
  position: absolute;
  top: -4rem;
  right: 0;
  background: none;
  border: none;
  color: white;
  font-size: var(--font-size-2xl);
  cursor: pointer;
  padding: var(--space-xs);
}

.mobile-nav nav {
  display: flex;
  flex-direction: column;
  gap: var(--space-lg);
}

.mobile-nav a {
  color: white;
  text-decoration: none;
  font-size: var(--font-size-2xl);
  font-weight: 500;
  transition: color var(--transition);
}

.mobile-nav a:hover {
  color: var(--accent-light);
}

/* Floating Social Icons */
.social-float {
  position: fixed;
  right: var(--space-lg);
  top: 50%;
  transform: translateY(-50%);
  display: flex;
  flex-direction: column;
  gap: var(--space-sm);
  z-index: 50;
}

.social-link {
  width: 50px;
  height: 50px;
  background: var(--surface);
  border: 1px solid var(--border);
  border-radius: var(--radius-full);
  display: flex;
  align-items: center;
  justify-content: center;
  color: var(--text-secondary);
  text-decoration: none;
  transition: all var(--transition);
  backdrop-filter: blur(10px);
  box-shadow: var(--shadow);
}

.social-link:hover {
  background: var(--accent);
  color: white;
  transform: translateX(-5px);
  box-shadow: 0 8px 25px rgba(99, 102, 241, 0.3);
}

/* Hero Section */
.hero {
  min-height: 100vh;
  display: flex;
  align-items: center;
  padding: var(--space-3xl) var(--space-lg) var(--space-2xl);
  background: var(--gradient-surface);
  position: relative;
}

.hero-content {
  max-width: 1200px;
  margin: 0 auto;
  display: grid;
  grid-template-columns: 1.5fr 1fr;
  gap: var(--space-3xl);
  align-items: center;
  width: 100%;
}

.hero-text h1 {
  font-size: clamp(var(--font-size-3xl), 6vw, var(--font-size-6xl));
  font-weight: 800;
  line-height: 1.1;
  margin-bottom: var(--space-md);
  background: linear-gradient(135deg, var(--primary) 0%, var(--accent) 100%);
  -webkit-background-clip: text;
  -webkit-text-fill-color: transparent;
  background-clip: text;
}

.hero-subtitle {
  font-size: var(--font-size-xl);
  color: var(--text-secondary);
  font-weight: 400;
  margin-bottom: var(--space-xl);
  max-width: 90%;
  line-height: 1.5;
}

.hero-tags {
  display: flex;
  flex-wrap: wrap;
  gap: var(--space-sm);
  margin-bottom: var(--space-xl);
}

.tag {
  background: var(--surface);
  border: 1px solid var(--border);
  padding: var(--space-xs) var(--space-md);
  border-radius: var(--radius-full);
  font-size: var(--font-size-sm);
  font-weight: 500;
  color: var(--text-secondary);
  transition: all var(--transition);
  backdrop-filter: blur(10px);
}

.tag:hover {
  background: var(--accent);
  color: white;
  transform: translateY(-2px);
  box-shadow: 0 8px 25px rgba(99, 102, 241, 0.3);
}

.hero-cta {
  display: flex;
  gap: var(--space-md);
  align-items: center;
}

.btn-primary, .btn-secondary {
  padding: var(--space-sm) var(--space-lg);
  border-radius: var(--radius-lg);
  font-weight: 600;
  text-decoration: none;
  transition: all var(--transition);
  display: inline-flex;
  align-items: center;
  font-size: var(--font-size-sm);
}

.btn-primary {
  background: var(--gradient-accent);
  color: white;
  border: none;
  box-shadow: var(--shadow);
}

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

.btn-secondary {
  background: transparent;
  color: var(--text-primary);
  border: 1px solid var(--border);
}

.btn-secondary:hover {
  background: var(--surface-hover);
  border-color: var(--accent);
}

.hero-image {
  position: relative;
  display: flex;
  justify-content: center;
}

.profile-img {
  width: 300px;
  height: 300px;
  border-radius: var(--radius-full);
  object-fit: cover;
  border: 4px solid var(--surface);
  box-shadow: var(--shadow-xl);
  transition: transform var(--transition-slow);
  position: relative;
  z-index: 2;
}

.profile-img:hover {
  transform: scale(1.05);
}

.image-glow {
  position: absolute;
  top: 50%;
  left: 50%;
  transform: translate(-50%, -50%);
  width: 320px;
  height: 320px;
  background: var(--gradient-accent);
  border-radius: var(--radius-full);
  opacity: 0.1;
  z-index: 1;
  animation: glow 4s ease-in-out infinite alternate;
}

@keyframes glow {
  from { transform: translate(-50%, -50%) scale(1); opacity: 0.1; }
  to { transform: translate(-50%, -50%) scale(1.1); opacity: 0.2; }
}

/* Section Styling */
.section {
  padding: var(--space-3xl) 0;
  position: relative;
}

.section-alt {
  background: var(--surface-alt);
}

.section-header {
  text-align: center;
  margin-bottom: var(--space-3xl);
  max-width: 800px;
  margin-left: auto;
  margin-right: auto;
}

.section-title {
  font-size: var(--font-size-4xl);
  font-weight: 700;
  margin-bottom: var(--space-md);
  background: var(--gradient-primary);
  -webkit-background-clip: text;
  -webkit-text-fill-color: transparent;
  background-clip: text;
}

.section-subtitle {
  font-size: var(--font-size-lg);
  color: var(--text-secondary);
  max-width: 600px;
  margin: 0 auto;
  line-height: 1.6;
}

/* Expertise Cards */
.expertise-grid {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(280px, 1fr));
  gap: var(--space-lg);
  margin-top: var(--space-xl);
}

.expertise-card {
  background: var(--surface);
  border: 1px solid var(--border);
  border-radius: var(--radius-2xl);
  padding: var(--space-xl);
  transition: all var(--transition);
  position: relative;
  overflow: hidden;
}

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

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

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

.card-icon {
  width: 60px;
  height: 60px;
  background: var(--gradient-accent);
  border-radius: var(--radius-xl);
  display: flex;
  align-items: center;
  justify-content: center;
  margin-bottom: var(--space-md);
  color: white;
  font-size: var(--font-size-2xl);
}

.expertise-card h3 {
  font-size: var(--font-size-xl);
  font-weight: 600;
  margin-bottom: var(--space-sm);
  color: var(--text-primary);
}

.expertise-card p {
  color: var(--text-secondary);
  line-height: 1.6;
}

/* Projects Grid */
/* Ensure proper grid layout and prevent expansion affecting adjacent cards */
.projects-grid {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(350px, 1fr));
  gap: var(--space-xl);
  margin-top: var(--space-xl);
  align-items: start; /* This is key - prevents cards from stretching */
}

.project-card {
  background: var(--surface);
  border-radius: var(--radius-2xl);
  overflow: hidden;
  box-shadow: var(--shadow);
  transition: all var(--transition-slow);
  border: 1px solid var(--border);
  height: fit-content; /* Prevents unwanted stretching */
  align-self: start; /* Ensures each card only takes the space it needs */
}

.project-card:hover {
  transform: translateY(-10px);
  box-shadow: var(--shadow-xl);
}

.project-image {
  position: relative;
  overflow: hidden;
  height: 200px;
}

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

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

.project-overlay {
  position: absolute;
  top: var(--space-sm);
  right: var(--space-sm);
  background: rgba(0, 0, 0, 0.7);
  color: white;
  padding: var(--space-xs) var(--space-sm);
  border-radius: var(--radius);
  font-size: var(--font-size-xs);
  font-weight: 500;
  backdrop-filter: blur(10px);
}

.project-header {
  display: flex;
  align-items: center;
  padding: var(--space-lg);
  cursor: pointer;
  transition: all var(--transition);
  position: relative;
}

.project-header:hover {
  background: var(--surface-hover);
}

.project-title-section {
  flex: 1;
}

.project-title-section h3 {
  font-size: var(--font-size-xl);
  font-weight: 600;
  margin-bottom: var(--space-xs);
  color: var(--text-primary);
  line-height: 1.3;
}

.project-summary {
  color: var(--text-secondary);
  font-size: var(--font-size-sm);
  margin: 0;
}

.project-expand-icon {
  margin-left: var(--space-md);
  color: var(--accent);
  transition: transform var(--transition);
  font-size: var(--font-size-lg);
}

.project-card.expanded .project-expand-icon {
  transform: rotate(180deg);
}

.project-content {
  max-height: 0;
  overflow: hidden;
  transition: max-height var(--transition-slow), padding var(--transition-slow), opacity var(--transition-slow), visibility var(--transition-slow);
  padding: 0 var(--space-lg);
  opacity: 0;
  visibility: hidden;
}

.project-card.expanded .project-content {
  max-height: 400px;
  padding: 0 var(--space-lg) var(--space-lg);
  opacity: 1;
  visibility: visible;
}

/* Ensure only expanded cards show content */
.project-card:not(.expanded) .project-content {
  max-height: 0 !important;
  padding: 0 var(--space-lg) !important;
  opacity: 0 !important;
  visibility: hidden !important;
}

.project-content p {
  color: var(--text-secondary);
  line-height: 1.6;
  margin-bottom: var(--space-md);
}

.project-tech {
  display: flex;
  flex-wrap: wrap;
  gap: var(--space-xs);
  margin-bottom: var(--space-md);
}

.project-tech span {
  background: var(--surface-alt);
  color: var(--text-secondary);
  padding: var(--space-xs) var(--space-sm);
  border-radius: var(--radius);
  font-size: var(--font-size-xs);
  font-weight: 500;
  transition: all var(--transition);
}

.project-tech span:hover {
  background: var(--accent-light);
  color: white;
  transform: scale(1.05);
}

/* Project Actions */
.project-actions {
  margin-top: var(--space-md);
  padding-top: var(--space-md);
  border-top: 1px solid var(--border-light);
}

.project-link {
  display: inline-flex;
  align-items: center;
  gap: var(--space-xs);
  padding: var(--space-xs) var(--space-md);
  background: var(--surface-alt);
  color: var(--text-primary);
  text-decoration: none;
  border-radius: var(--radius);
  font-size: var(--font-size-sm);
  font-weight: 500;
  transition: all var(--transition);
  border: 1px solid var(--border);
}

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

.project-link i {
  font-size: var(--font-size-base);
}

/* Timeline */
.journey-timeline {
  max-width: 900px;
  margin: 0 auto;
  position: relative;
}

.timeline-item {
  margin-bottom: var(--space-xl);
  background: var(--surface);
  border-radius: var(--radius-2xl);
  border: 1px solid var(--border);
  overflow: hidden;
  transition: all var(--transition);
  position: relative;
}

.timeline-item:hover {
  box-shadow: var(--shadow-lg);
  border-color: var(--accent-light);
}

.timeline-header {
  display: flex;
  align-items: center;
  padding: var(--space-lg);
  cursor: pointer;
  transition: all var(--transition);
  position: relative;
}

.timeline-header:hover {
  background: var(--surface-hover);
}

.timeline-date {
  min-width: 140px;
  font-weight: 600;
  color: var(--accent);
  font-size: var(--font-size-sm);
  flex-shrink: 0;
  margin-right: var(--space-lg);
}

.timeline-title-section {
  flex: 1;
}

.timeline-title-section h3 {
  font-size: var(--font-size-xl);
  font-weight: 600;
  margin-bottom: var(--space-xs);
  color: var(--text-primary);
  line-height: 1.3;
}

.timeline-title-section h4 {
  color: var(--text-secondary);
  font-weight: 500;
  margin: 0;
  font-size: var(--font-size-base);
}

.timeline-expand-icon {
  margin-left: var(--space-md);
  color: var(--accent);
  transition: transform var(--transition);
  font-size: var(--font-size-lg);
}

.timeline-item.expanded .timeline-expand-icon {
  transform: rotate(180deg);
}

.timeline-content {
  max-height: 0;
  overflow: hidden;
  transition: max-height var(--transition-slow), padding var(--transition-slow);
  padding: 0 var(--space-lg);
}

.timeline-item.expanded .timeline-content {
  max-height: 300px;
  padding: 0 var(--space-lg) var(--space-lg);
}

.timeline-content p {
  color: var(--text-secondary);
  line-height: 1.6;
  margin-bottom: var(--space-md);
}

.timeline-highlights {
  display: flex;
  flex-wrap: wrap;
  gap: var(--space-xs);
}

.timeline-highlights span {
  background: var(--gradient-accent);
  color: white;
  padding: var(--space-xs) var(--space-sm);
  border-radius: var(--radius);
  font-size: var(--font-size-xs);
  font-weight: 500;
  transition: transform var(--transition);
}

.timeline-highlights span:hover {
  transform: scale(1.05);
  cursor: default;
}

/* Publications */
.publications-grid {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(350px, 1fr));
  gap: var(--space-lg);
  margin-top: var(--space-xl);
}

.publication-card {
  background: var(--surface);
  border: 1px solid var(--border);
  border-radius: var(--radius-2xl);
  padding: var(--space-lg);
  transition: all var(--transition);
}

.publication-card:hover {
  transform: translateY(-5px);
  box-shadow: var(--shadow-lg);
  border-color: var(--accent-light);
}

.publication-header {
  display: flex;
  justify-content: space-between;
  align-items: flex-start;
  margin-bottom: var(--space-sm);
  gap: var(--space-sm);
}

.publication-header h3 {
  font-size: var(--font-size-lg);
  font-weight: 600;
  color: var(--text-primary);
  line-height: 1.4;
}

.publication-year {
  background: var(--gradient-accent);
  color: white;
  padding: var(--space-xs) var(--space-sm);
  border-radius: var(--radius);
  font-size: var(--font-size-xs);
  font-weight: 600;
  flex-shrink: 0;
}

.publication-journal {
  font-style: italic;
  color: var(--accent);
  font-weight: 500;
  margin-bottom: var(--space-sm);
}

.publication-description {
  color: var(--text-secondary);
  line-height: 1.6;
  margin-bottom: var(--space-md);
}

.publication-authors {
  font-size: var(--font-size-sm);
  color: var(--text-muted);
  margin-bottom: var(--space-md);
}

.publication-link {
  color: var(--accent);
  text-decoration: none;
  font-weight: 500;
  display: inline-flex;
  align-items: center;
  gap: var(--space-xs);
  transition: color var(--transition);
}

.publication-link:hover {
  color: var(--accent-hover);
}

/* Certifications Summary */
.certifications-summary {
  background: var(--surface);
  border: 1px solid var(--border);
  border-radius: var(--radius-2xl);
  padding: var(--space-xl);
  margin-top: var(--space-2xl);
  text-align: center;
}

.certifications-summary h3 {
  font-size: var(--font-size-2xl);
  font-weight: 600;
  margin-bottom: var(--space-sm);
  color: var(--text-primary);
}

.certifications-summary > p {
  color: var(--text-secondary);
  margin-bottom: var(--space-lg);
  max-width: 600px;
  margin-left: auto;
  margin-right: auto;
}

.cert-categories {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(200px, 1fr));
  gap: var(--space-md);
  margin-bottom: var(--space-lg);
}

.cert-category {
  background: var(--surface-alt);
  padding: var(--space-md);
  border-radius: var(--radius-lg);
  text-align: center;
}

.cert-category h4 {
  font-size: var(--font-size-lg);
  font-weight: 600;
  margin-bottom: var(--space-xs);
  color: var(--text-primary);
}

.cert-category span {
  color: var(--text-secondary);
  font-size: var(--font-size-sm);
}

.view-all-certs {
  background: var(--gradient-accent);
  color: white;
  padding: var(--space-sm) var(--space-lg);
  border-radius: var(--radius-lg);
  text-decoration: none;
  font-weight: 600;
  display: inline-flex;
  align-items: center;
  gap: var(--space-xs);
  transition: all var(--transition);
}

.view-all-certs:hover {
  transform: translateY(-2px);
  box-shadow: var(--shadow-lg);
}

/* Detailed Certifications */
.certifications-detailed {
  background: var(--surface-alt);
}

.cert-filter {
  display: flex;
  justify-content: center;
  gap: var(--space-sm);
  margin-bottom: var(--space-xl);
  flex-wrap: wrap;
}

.cert-filter-btn {
  background: var(--surface);
  border: 1px solid var(--border);
  padding: var(--space-sm) var(--space-md);
  border-radius: var(--radius-lg);
  font-weight: 500;
  color: var(--text-secondary);
  cursor: pointer;
  transition: all var(--transition);
}

.cert-filter-btn:hover,
.cert-filter-btn.active {
  background: var(--accent);
  color: white;
  border-color: var(--accent);
}

.certifications-grid {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(300px, 1fr));
  gap: var(--space-md);
}

.cert-card {
  background: var(--surface);
  border: 1px solid var(--border);
  border-radius: var(--radius-lg);
  padding: var(--space-md);
  transition: all var(--transition);
}

.cert-card:hover {
  transform: translateY(-3px);
  box-shadow: var(--shadow);
  border-color: var(--accent-light);
}

.cert-card h4 {
  font-size: var(--font-size-lg);
  font-weight: 600;
  margin-bottom: var(--space-xs);
  color: var(--text-primary);
  line-height: 1.3;
}

.cert-provider {
  color: var(--text-secondary);
  font-size: var(--font-size-sm);
  margin-bottom: var(--space-sm);
}

.cert-card a {
  color: var(--accent);
  text-decoration: none;
  font-weight: 500;
  font-size: var(--font-size-sm);
  transition: color var(--transition);
}

.cert-card a:hover {
  color: var(--accent-hover);
}

/* Footer */
.footer {
  background: var(--primary);
  color: white;
  padding: var(--space-2xl) 0 var(--space-lg);
}

.footer-content {
  display: flex;
  justify-content: space-between;
  align-items: center;
  margin-bottom: var(--space-lg);
}

.footer-info h3 {
  font-size: var(--font-size-xl);
  font-weight: 600;
  margin-bottom: var(--space-xs);
}

.footer-info p {
  color: var(--text-muted);
}

.footer-links {
  display: flex;
  gap: var(--space-md);
}

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

.footer-links a:hover {
  background: var(--accent);
  transform: translateY(-2px);
}

.footer-bottom {
  text-align: center;
  padding-top: var(--space-lg);
  border-top: 1px solid rgba(255, 255, 255, 0.1);
  color: var(--text-muted);
}

/* Back to Top Button */
.back-to-top {
  position: fixed;
  bottom: var(--space-lg);
  right: var(--space-lg);
  width: 50px;
  height: 50px;
  background: var(--gradient-accent);
  color: white;
  border: none;
  border-radius: var(--radius-full);
  cursor: pointer;
  opacity: 0;
  visibility: hidden;
  transition: all var(--transition);
  display: flex;
  justify-content: center;
  align-items: center;
  box-shadow: var(--shadow-lg);
  z-index: 40;
}

.back-to-top.visible {
  opacity: 1;
  visibility: visible;
}

.back-to-top:hover {
  transform: translateY(-3px);
  box-shadow: var(--shadow-xl);
}

/* Responsive Design */
@media (max-width: 1024px) {
  .social-float {
    display: none;
  }
  
  :root {
    --space-3xl: 4rem;
    --space-2xl: 3rem;
  }
}

@media (max-width: 768px) {
  :root {
    --space-lg: 1rem;
    --space-xl: 2rem;
    --space-2xl: 3rem;
    --space-3xl: 4rem;
  }

  .nav-links {
    display: none;
  }

  .mobile-menu-toggle {
    display: block;
  }

  .hero-content {
    grid-template-columns: 1fr;
    text-align: center;
    gap: var(--space-xl);
  }

  .hero-text {
    order: 2;
  }

  .hero-image {
    order: 1;
  }

  .hero-text h1 {
    font-size: clamp(1.75rem, 5vw, 2.5rem);
    line-height: 1.2;
  }

  .profile-img {
    width: 250px;
    height: 250px;
  }

  .image-glow {
    width: 270px;
    height: 270px;
  }

  .hero-cta {
    justify-content: center;
  }

  .section {
    padding: var(--space-2xl) 0;
  }

  .section-title {
    font-size: var(--font-size-3xl);
  }

  .expertise-grid,
  .projects-grid {
    grid-template-columns: 1fr;
  }

  .timeline-item {
    margin-bottom: var(--space-md);
  }

  .timeline-header {
    flex-direction: column;
    align-items: flex-start;
    gap: var(--space-sm);
    padding: var(--space-md);
  }

  .timeline-date {
    min-width: auto;
    font-size: var(--font-size-xs);
    text-transform: uppercase;
    letter-spacing: 0.5px;
    margin-right: 0;
    order: 1;
  }

  .timeline-title-section {
    order: 2;
  }

  .timeline-expand-icon {
    position: absolute;
    top: var(--space-md);
    right: var(--space-md);
    margin-left: 0;
  }

  .timeline-item.expanded .timeline-content {
    padding: 0 var(--space-md) var(--space-md);
  }

  .project-header {
    flex-direction: column;
    align-items: flex-start;
    gap: var(--space-sm);
    padding: var(--space-md);
  }

  .project-title-section {
    order: 1;
  }

  .project-expand-icon {
    position: absolute;
    top: var(--space-md);
    right: var(--space-md);
    margin-left: 0;
  }

  .project-card.expanded .project-content {
    padding: 0 var(--space-md) var(--space-md);
  }

  .footer-content {
    flex-direction: column;
    gap: var(--space-md);
    text-align: center;
  }

  .container {
    padding: 0 var(--space-sm);
  }
}

@media (max-width: 480px) {
  .hero-text h1 {
    font-size: 1.75rem;
    line-height: 1.2;
    word-break: break-word;
    hyphens: auto;
  }

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

  .hero-tags {
    justify-content: center;
  }

  .hero-cta {
    flex-direction: column;
    align-items: stretch;
  }

  .btn-primary,
  .btn-secondary {
    text-align: center;
    justify-content: center;
  }

  .cert-filter {
    flex-direction: column;
    align-items: center;
  }

  .cert-filter-btn {
    width: 100%;
    max-width: 200px;
  }
}

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

.fade-in-up {
  animation: fadeInUp 0.6s ease forwards;
}

/* Enhanced Visual Effects */
.expertise-card::after {
  content: '';
  position: absolute;
  top: 0;
  left: 0;
  right: 0;
  bottom: 0;
  background: linear-gradient(45deg, transparent 49%, rgba(99, 102, 241, 0.03) 50%, transparent 51%);
  opacity: 0;
  transition: opacity var(--transition);
  pointer-events: none;
}

.expertise-card:hover::after {
  opacity: 1;
}

/* Enhanced Focus Styles */
.keyboard-nav *:focus {
  outline: 2px solid var(--accent) !important;
  outline-offset: 2px !important;
  border-radius: var(--radius-sm);
}

/* Loading State */
.loading {
  opacity: 0.7;
  pointer-events: none;
  position: relative;
}

.loading::after {
  content: '';
  position: absolute;
  top: 50%;
  left: 50%;
  width: 20px;
  height: 20px;
  margin: -10px 0 0 -10px;
  border: 2px solid var(--border);
  border-top-color: var(--accent);
  border-radius: 50%;
  animation: spin 1s linear infinite;
}

@keyframes spin {
  to { transform: rotate(360deg); }
}

/* Enhanced Hover Effects */
.tag:hover,
.btn-primary:hover,
.project-tech span:hover {
  cursor: default;
}

.project-card:hover .project-tech span {
  background: var(--accent-light);
  color: white;
}

.timeline-highlights span:hover {
  transform: scale(1.05);
  cursor: default;
}

/* Improved Typography */
.hero-text h1 {
  text-shadow: 0 1px 2px rgba(0, 0, 0, 0.1);
}

.section-title {
  position: relative;
}

.section-title::after {
  content: '';
  position: absolute;
  bottom: -10px;
  left: 50%;
  transform: translateX(-50%);
  width: 60px;
  height: 3px;
  background: var(--gradient-accent);
  border-radius: var(--radius-full);
}

/* Better Visual Hierarchy */
.publication-card:hover .publication-header h3 {
  background: var(--gradient-primary);
  -webkit-background-clip: text;
  -webkit-text-fill-color: transparent;
  background-clip: text;
}

/* Enhanced Mobile Experience */
@media (max-width: 768px) {
  .hero-tags {
    max-width: 100%;
    overflow-x: auto;
    flex-wrap: nowrap;
    padding-bottom: var(--space-xs);
    scrollbar-width: none;
    -ms-overflow-style: none;
  }
  
  .hero-tags::-webkit-scrollbar {
    display: none;
  }
  
  .tag {
    flex-shrink: 0;
  }
}

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

.social-float .social-link:nth-child(1) {
  animation: float 6s ease-in-out infinite;
}

.social-float .social-link:nth-child(2) {
  animation: float 6s ease-in-out infinite 1s;
}

/* Enhanced States */
.cert-card[data-category="ai-ml"] {
  border-left: 3px solid #10b981;
}

.cert-card[data-category="cs"] {
  border-left: 3px solid #f59e0b;
}

.cert-card[data-category="pm"] {
  border-left: 3px solid #ef4444;
}

/* Image Lightbox */
.lightbox-modal {
  position: fixed;
  top: 0;
  left: 0;
  width: 100%;
  height: 100%;
  z-index: 2000;
  opacity: 0;
  visibility: hidden;
  transition: all var(--transition-slow);
}

.lightbox-modal.active {
  opacity: 1;
  visibility: visible;
}

.lightbox-overlay {
  position: absolute;
  top: 0;
  left: 0;
  width: 100%;
  height: 100%;
  background: rgba(0, 0, 0, 0.9);
  backdrop-filter: blur(10px);
}

.lightbox-content {
  position: absolute;
  top: 50%;
  left: 50%;
  transform: translate(-50%, -50%) scale(0.8);
  max-width: 90vw;
  max-height: 90vh;
  transition: transform var(--transition-slow);
  z-index: 2001;
}

.lightbox-modal.active .lightbox-content {
  transform: translate(-50%, -50%) scale(1);
}

.lightbox-image {
  max-width: 100%;
  max-height: 85vh;
  height: auto;
  border-radius: var(--radius-lg);
  box-shadow: var(--shadow-xl);
  object-fit: contain;
}

.lightbox-close {
  position: absolute;
  top: -50px;
  right: 0;
  background: rgba(255, 255, 255, 0.1);
  border: none;
  color: white;
  width: 40px;
  height: 40px;
  border-radius: var(--radius-full);
  cursor: pointer;
  transition: all var(--transition);
  display: flex;
  align-items: center;
  justify-content: center;
  backdrop-filter: blur(10px);
}

.lightbox-close:hover {
  background: rgba(255, 255, 255, 0.2);
  transform: scale(1.1);
}

.lightbox-caption {
  text-align: center;
  color: white;
  margin-top: var(--space-md);
  font-weight: 500;
  font-size: var(--font-size-lg);
  text-shadow: 0 2px 10px rgba(0, 0, 0, 0.5);
}

/* Project Image Cursor */
.project-image {
  cursor: pointer;
  position: relative;
}

.project-image::after {
  content: '🔍';
  position: absolute;
  top: 50%;
  left: 50%;
  transform: translate(-50%, -50%);
  background: rgba(0, 0, 0, 0.7);
  color: white;
  width: 50px;
  height: 50px;
  border-radius: var(--radius-full);
  display: flex;
  align-items: center;
  justify-content: center;
  font-size: 1.2rem;
  opacity: 0;
  transition: opacity var(--transition);
  pointer-events: none;
  backdrop-filter: blur(5px);
}

.project-card:hover .project-image::after {
  opacity: 1;
}

/* Mobile Lightbox Adjustments */
@media (max-width: 768px) {
  .lightbox-close {
    top: -40px;
    right: -10px;
    width: 35px;
    height: 35px;
  }
  
  .lightbox-image {
    max-height: 80vh;
  }
  
  .lightbox-caption {
    font-size: var(--font-size-base);
    margin-top: var(--space-sm);
  }
}

/* Print Styles */
@media print {
  .header,
  .social-float,
  .back-to-top,
  .mobile-nav {
    display: none !important;
  }

  .hero {
    min-height: auto;
    padding: 2rem 0;
  }

  .section {
    padding: 1rem 0;
    break-inside: avoid;
  }

  .project-card,
  .expertise-card,
  .publication-card {
    break-inside: avoid;
    box-shadow: none;
    border: 1px solid #ccc;
  }
  
  .hero-text h1 {
    color: var(--primary) !important;
    -webkit-text-fill-color: var(--primary) !important;
  }
  
  .section-title {
    color: var(--primary) !important;
    -webkit-text-fill-color: var(--primary) !important;
  }
}