:root {
  /* Color system */
  --primary: #2563eb;
  --primary-dark: #1d4ed8;
  --secondary: #10b981;
  --secondary-dark: #059669;
  --background: #ffffff;
  --background-alt: #f3f4f6;
  --text: #1f2937;
  --text-light: #6b7280;
  --border: #e5e7eb;
  
  /* Dark mode colors */
  --dark-background: #111827;
  --dark-background-alt: #1f2937;
  --dark-text: #f9fafb;
  --dark-text-light: #9ca3af;
  --dark-border: #374151;
  
  /* Typography */
  --font-sans: 'Inter', system-ui, -apple-system, sans-serif;
  --font-mono: 'JetBrains Mono', monospace;
  
  /* Spacing */
  --spacing-xs: 0.25rem;
  --spacing-sm: 0.5rem;
  --spacing-md: 1rem;
  --spacing-lg: 1.5rem;
  --spacing-xl: 2rem;
  --spacing-2xl: 3rem;
  
  /* Border radius */
  --radius-sm: 0.25rem;
  --radius-md: 0.5rem;
  --radius-lg: 1rem;
  --radius-full: 9999px;
  
  /* Shadows */
  --shadow-sm: 0 1px 2px 0 rgb(0 0 0 / 0.05);
  --shadow-md: 0 4px 6px -1px rgb(0 0 0 / 0.1);
  --shadow-lg: 0 10px 15px -3px rgb(0 0 0 / 0.1);
}

/* Base styles */
body {
  font-family: var(--font-sans);
  color: var(--text);
  background-color: var(--background);
  line-height: 1.5;
  margin: 0;
  transition: background-color 0.3s, color 0.3s;
}

/* Dark mode */
body.dark-mode {
  color: var(--dark-text);
  background-color: var(--dark-background);
}

/* Typography */
h1, h2, h3, h4, h5, h6 {
  margin-bottom: var(--spacing-md);
  font-weight: 600;
  line-height: 1.2;
  color: var(--text);
}

.dark-mode h1, 
.dark-mode h2, 
.dark-mode h3, 
.dark-mode h4, 
.dark-mode h5, 
.dark-mode h6 {
  color: var(--dark-text);
}

h1 { font-size: 2.5rem; }
h2 { font-size: 2rem; }
h3 { font-size: 1.5rem; }

p { 
  margin-bottom: var(--spacing-md);
  color: var(--text);
}

.dark-mode p {
  color: var(--dark-text);
}

/* Links */
a {
  color: var(--primary);
  transition: color 0.2s;
}

.dark-mode a {
  color: var(--primary);
}

a:hover {
  color: var(--primary-dark);
}

/* Container */
.container {
  width: 100%;
  max-width: 1200px;
  margin: 0 auto;
  padding: 0 var(--spacing-md);
}

/* Card */
.card {
  background-color: var(--background);
  border: 1px solid var(--border);
  border-radius: var(--radius-lg);
  padding: 0;
  transition: transform 0.2s, box-shadow 0.2s;
  overflow: hidden;
}

.card-body {
  padding: var(--spacing-lg);
}

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

.dark-mode .card {
  background-color: var(--dark-background-alt);
  border-color: var(--dark-border);
}

.card-img-top {
  width: 100%;
  height: 240px;
  object-fit: cover;
  border-bottom: 1px solid var(--border);
  background-color: var(--background-alt);
}

.dark-mode .card-img-top {
  border-color: var(--dark-border);
  background-color: var(--dark-background);
  filter: brightness(1.1) contrast(1.1);
}

/* List groups */
.list-group-item {
  background-color: var(--background);
  border-color: var(--border);
  color: var(--text);
  transition: background-color 0.3s ease, color 0.3s ease, border-color 0.3s ease;
}

.dark-mode .list-group-item {
  background-color: var(--dark-background-alt);
  border-color: var(--dark-border);
  color: var(--dark-text);
}

/* Button */
.btn {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  padding: var(--spacing-sm) var(--spacing-lg);
  border-radius: var(--radius-md);
  font-weight: 500;
  text-decoration: none;
  transition: all 0.2s;
  cursor: pointer;
  border: 1px solid transparent;
  line-height: 1;
}

.btn svg {
  display: block;
  width: 1em;
  height: 1em;
}

.btn-primary {
  background-color: var(--primary);
  color: white;
  border-color: var(--primary);
}

.btn-primary:hover {
  background-color: var(--primary-dark);
  border-color: var(--primary-dark);
  color: white;
}

.dark-mode .btn-primary {
  background-color: var(--primary);
  color: var(--dark-text);
  border-color: var(--primary);
}

.dark-mode .btn-primary:hover {
  background-color: var(--primary-dark);
  border-color: var(--primary-dark);
  color: var(--dark-text);
}

.btn-secondary {
  background-color: var(--secondary);
  color: white;
  border-color: var(--secondary);
}

.btn-secondary:hover {
  background-color: var(--secondary-dark);
  border-color: var(--secondary-dark);
  color: white;
}

.dark-mode .btn-secondary {
  background-color: var(--secondary);
  color: var(--dark-text);
  border-color: var(--secondary);
}

.dark-mode .btn-secondary:hover {
  background-color: var(--secondary-dark);
  border-color: var(--secondary-dark);
  color: var(--dark-text);
}

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

.btn-outline-primary:hover {
  background-color: var(--primary);
  color: white;
}

.dark-mode .btn-outline-primary {
  color: var(--dark-text);
  border-color: var(--dark-text);
  background-color: transparent;
}

.dark-mode .btn-outline-primary:hover {
  background-color: var(--dark-text);
  color: var(--dark-background);
  border-color: var(--dark-text);
}

.btn-sm {
  padding: var(--spacing-xs) var(--spacing-xs);
  font-size: 0.875rem;
  min-height: 32px;
  min-width: 32px;
}

/* Navbar */
.navbar {
  position: sticky;
  top: 0;
  z-index: 1000;
  background-color: var(--background);
  border-bottom: 1px solid var(--border);
  padding: var(--spacing-md) 0;
  backdrop-filter: blur(8px);
}

.dark-mode .navbar {
  background-color: var(--dark-background);
  border-color: var(--dark-border);
}

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

.dark-mode .nav-link {
  color: var(--dark-text);
}

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

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

.nav-link.active {
  color: var(--primary) !important;
}

.dropdown-menu {
  background-color: var(--background);
  border-color: var(--border);
}

.dark-mode .dropdown-menu {
  background-color: var(--dark-background-alt);
  border-color: var(--dark-border);
}

.dropdown-item {
  color: var(--text);
}

.dark-mode .dropdown-item {
  color: var(--dark-text);
}

.dropdown-item:hover {
  background-color: var(--background-alt);
  color: var(--primary);
}

.dark-mode .dropdown-item:hover {
  background-color: var(--dark-background);
  color: var(--primary);
}

/* Grid */
.grid {
  display: grid;
  gap: var(--spacing-lg);
}

.grid-2 {
  grid-template-columns: repeat(2, 1fr);
}

.grid-3 {
  grid-template-columns: repeat(3, 1fr);
}

@media (max-width: 768px) {
  .grid-2, .grid-3 {
    grid-template-columns: 1fr;
  }
}

/* Utilities */
.text-gradient {
  background: linear-gradient(to right, var(--primary), var(--secondary));
  -webkit-background-clip: text;
  -webkit-text-fill-color: transparent;
}

.text-muted {
  color: var(--text-light) !important;
}

.dark-mode .text-muted {
  color: var(--dark-text-light) !important;
}

.animate-fade-in {
  animation: fadeIn 0.5s ease-in;
}

.animate-slide-up {
  animation: slideUp 0.5s ease-out;
}

@keyframes fadeIn {
  from { opacity: 0; }
  to { opacity: 1; }
}

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

/* Section */
.section {
  padding: var(--spacing-2xl) 0;
}

.bg-light {
  background-color: var(--background-alt) !important;
}

.dark-mode .bg-light {
  background-color: var(--dark-background-alt) !important;
}

/* Image */
.img-fluid {
  max-width: 100%;
  height: auto;
  border-radius: var(--radius-md);
}

/* Footer */
.footer {
  background-color: var(--background-alt);
  padding: var(--spacing-2xl) 0;
  margin-top: var(--spacing-2xl);
}

.dark-mode .footer {
  background-color: var(--dark-background-alt);
}

/* Timeline */
.timeline-content {
  background-color: var(--background-alt);
  color: var(--text);
}

.dark-mode .timeline-content {
  background-color: var(--dark-background-alt);
  color: var(--dark-text);
}

/* Lead text */
.lead {
  color: var(--text-light);
}

.dark-mode .lead {
  color: var(--dark-text-light);
}

/* Code and pre */
code, pre {
  background-color: var(--background-alt);
  color: var(--text);
}

.dark-mode code,
.dark-mode pre {
  background-color: var(--dark-background-alt);
  color: var(--dark-text);
}

/* Form elements */
input, textarea, select {
  background-color: var(--background);
  color: var(--text);
  border-color: var(--border);
}

.dark-mode input,
.dark-mode textarea,
.dark-mode select {
  background-color: var(--dark-background-alt);
  color: var(--dark-text);
  border-color: var(--dark-border);
}

/* Profile image */
.profile-image {
  width: 300px;
  height: 300px;
  object-fit: cover;
  border-radius: 50%;
  box-shadow: var(--shadow-lg);
}

.dark-mode .profile-image {
  border: 2px solid var(--dark-border);
}

/* Project Status */
.project-status {
  display: inline-flex;
  align-items: center;
  gap: var(--spacing-xs);
  padding: var(--spacing-xs) var(--spacing-sm);
  border-radius: var(--radius-full);
  font-size: 0.875rem;
  font-weight: 500;
  margin-bottom: var(--spacing-md);
}

.project-status::before {
  content: '';
  width: 8px;
  height: 8px;
  border-radius: 50%;
  background-color: currentColor;
  animation: pulse 2s infinite;
}

.project-status.in-progress {
  color: var(--primary);
  background-color: color-mix(in srgb, var(--primary) 15%, transparent);
}

.project-status.completed {
  color: var(--secondary);
  background-color: color-mix(in srgb, var(--secondary) 15%, transparent);
}

.dark-mode .project-status.in-progress {
  background-color: color-mix(in srgb, var(--primary) 25%, transparent);
}

.dark-mode .project-status.completed {
  background-color: color-mix(in srgb, var(--secondary) 25%, transparent);
}

@keyframes pulse {
  0% { opacity: 1; }
  50% { opacity: 0.5; }
  100% { opacity: 1; }
}

/* Project card specific styles */
.project-card {
  position: relative;
  overflow: hidden;
}

.project-card .card-img-top {
  transition: transform 0.3s ease;
}

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

.project-card .card-body {
  background: linear-gradient(
    to bottom,
    transparent,
    var(--background-alt) 10%
  );
}

.dark-mode .project-card .card-body {
  background: linear-gradient(
    to bottom,
    transparent,
    var(--dark-background-alt) 10%
  );
}

/* Image Lightbox */
.lightbox-overlay {
  position: fixed;
  top: 0;
  left: 0;
  width: 100%;
  height: 100%;
  background-color: rgba(0, 0, 0, 0.75);
  display: flex;
  align-items: center;
  justify-content: center;
  z-index: 9999;
  backdrop-filter: blur(5px);
  user-select: none;
  -webkit-user-select: none;
  opacity: 0;
  visibility: hidden;
  pointer-events: none;
  transition: opacity 0.2s ease-out, visibility 0s linear 0.2s, background-color 0.3s ease;
}

.dark-mode .lightbox-overlay {
  background-color: rgba(0, 0, 0, 0.6);
}

.lightbox-overlay.active {
  opacity: 1;
  visibility: visible;
  pointer-events: all;
  transition: opacity 0.2s ease-out, visibility 0s linear;
}

.lightbox-content {
  position: relative;
  max-width: 90vw;
  max-height: 85vh;
  display: flex;
  flex-direction: column;
  align-items: center;
  transform: scale(0.98);
  opacity: 0;
  transition: transform 0.25s cubic-bezier(0.4, 0.0, 0.2, 1),
              opacity 0.2s ease-out;
  will-change: transform, opacity;
}

.lightbox-overlay.active .lightbox-content {
  transform: scale(1);
  opacity: 1;
}

.lightbox-image {
  max-width: 90vw;
  max-height: 80vh;
  border-radius: var(--radius-lg);
  box-shadow: var(--shadow-lg);
  object-fit: contain;
  transform: scale(0.98);
  opacity: 0;
  transition: transform 0.25s cubic-bezier(0.4, 0.0, 0.2, 1),
              opacity 0.2s ease-out;
  will-change: transform, opacity;
}

.lightbox-overlay.active .lightbox-image {
  transform: scale(1);
  opacity: 1;
}

.lightbox-close {
  position: absolute;
  top: -40px;
  right: 0;
  background-color: var(--dark-background-alt);
  border: 1px solid var(--dark-text);
  border-radius: var(--radius-md);
  padding: var(--spacing-xs) var(--spacing-sm);
  cursor: pointer;
  color: var(--dark-text);
  font-size: 0.875rem;
  font-weight: 500;
  text-transform: uppercase;
  letter-spacing: 0.05em;
  transition: all 0.2s cubic-bezier(0.34, 1.56, 0.64, 1);
  z-index: 10000;
  display: inline-flex;
  align-items: center;
  gap: var(--spacing-xs);
}

.lightbox-close::before {
  content: 'esc';
  font-size: 0.75rem;
  opacity: 0.8;
}

.lightbox-close:hover {
  background-color: var(--dark-text);
  color: var(--dark-background);
  transform: translateY(-2px);
}

.lightbox-caption {
  position: absolute;
  bottom: var(--spacing-xl);
  left: 50%;
  transform: translateX(-50%);
  text-align: center;
  color: var(--dark-text);
  font-size: 1rem;
  background-color: var(--dark-background-alt);
  padding: var(--spacing-sm) var(--spacing-lg);
  border-radius: var(--radius-full);
  opacity: 0;
  transition: opacity 0.3s ease;
  box-shadow: var(--shadow-md);
  pointer-events: none;
  max-width: 90vw;
  overflow: hidden;
  text-overflow: ellipsis;
}

.lightbox-overlay.active .lightbox-caption {
  opacity: 1;
}

@media (max-width: 768px) {
  .lightbox-close {
    top: calc(-1 * var(--spacing-lg));
    padding: var(--spacing-xs) var(--spacing-md);
  }
  
  .lightbox-caption {
    font-size: 0.875rem;
    padding: var(--spacing-xs) var(--spacing-md);
    bottom: var(--spacing-lg);
  }
  
  .lightbox-image {
    max-width: 95vw;
    max-height: 75vh;
  }
}

/* Make images clickable */
.card-img-top,
.profile-image,
.img-fluid {
  cursor: pointer;
  user-select: none;
  -webkit-user-select: none;
}

@media (max-width: 768px) {
  .lightbox-close {
    top: var(--spacing-lg);
    right: var(--spacing-lg);
  }
  
  .lightbox-caption {
    font-size: 0.875rem;
    padding: var(--spacing-xs) var(--spacing-md);
    bottom: var(--spacing-lg);
  }
  
  .lightbox-image {
    max-width: 95vw;
    max-height: 75vh;
  }
}

.course-name {
  font-weight: 500;
  color: var(--text);
  transition: color 0.3s ease;
}

.dark-mode .course-name {
  color: var(--dark-text);
}

.dark-mode small.text-muted {
  color: var(--dark-text-light) !important;
  opacity: 0.8;
}