/* ============================================
   CSS Custom Properties (Design Tokens)
   ============================================ */
:root {
  /* Color Palette - Modern & Professional */
  --color-primary: hsl(210, 100%, 56%);
  --color-primary-dark: hsl(210, 100%, 46%);
  --color-primary-light: hsl(210, 100%, 96%);
  --color-accent: hsl(280, 85%, 65%);
  --color-accent-light: hsl(280, 85%, 95%);

  --color-text: hsl(220, 15%, 20%);
  --color-text-muted: hsl(220, 10%, 50%);
  --color-bg: hsl(0, 0%, 100%);
  --color-bg-alt: hsl(210, 20%, 98%);
  --color-bg-alt: hsl(210, 20%, 98%);
  --color-border: hsl(220, 15%, 90%);
  --color-header-bg: rgba(255, 255, 255, 0.95);

  /* Typography */
  --font-sans: 'Inter', -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, 'Helvetica Neue', Arial, sans-serif;
  --font-mono: 'JetBrains Mono', 'Fira Code', Consolas, Monaco, monospace;

  --text-xs: 0.75rem;
  --text-sm: 0.875rem;
  --text-base: 1rem;
  --text-lg: 1.125rem;
  --text-xl: 1.25rem;
  --text-2xl: 1.5rem;
  --text-3xl: 1.875rem;
  --text-4xl: 2.25rem;
  --text-5xl: 3rem;

  --font-light: 300;
  --font-normal: 400;
  --font-medium: 500;
  --font-semibold: 600;
  --font-bold: 700;

  /* Spacing */
  --space-1: 0.25rem;
  --space-2: 0.5rem;
  --space-3: 0.75rem;
  --space-4: 1rem;
  --space-5: 1.25rem;
  --space-6: 1.5rem;
  --space-8: 2rem;
  --space-10: 2.5rem;
  --space-12: 3rem;
  --space-16: 4rem;
  --space-20: 5rem;

  /* Layout */
  --container-width: 1200px;
  --container-padding: var(--space-6);
  --border-radius: 0.5rem;
  --border-radius-lg: 1rem;

  /* Transitions */
  --transition-fast: 150ms cubic-bezier(0.4, 0, 0.2, 1);
  --transition-base: 250ms cubic-bezier(0.4, 0, 0.2, 1);
  --transition-slow: 350ms cubic-bezier(0.4, 0, 0.2, 1);

  /* Shadows */
  --shadow-sm: 0 1px 2px 0 rgba(0, 0, 0, 0.05);
  --shadow-md: 0 4px 6px -1px rgba(0, 0, 0, 0.1), 0 2px 4px -1px rgba(0, 0, 0, 0.06);
  --shadow-lg: 0 10px 15px -3px rgba(0, 0, 0, 0.1), 0 4px 6px -2px rgba(0, 0, 0, 0.05);
  --shadow-xl: 0 20px 25px -5px rgba(0, 0, 0, 0.1), 0 10px 10px -5px rgba(0, 0, 0, 0.04);
}

/* ============================================
   Dark Mode Theme
   ============================================ */
[data-theme="dark"] {
  --color-primary: hsl(210, 100%, 60%);
  --color-primary-dark: hsl(210, 100%, 70%);
  --color-primary-light: hsl(210, 30%, 25%);
  --color-accent: hsl(280, 85%, 70%);
  --color-accent-light: hsl(280, 30%, 25%);

  --color-text: hsl(220, 20%, 95%);
  --color-text-muted: hsl(220, 15%, 70%);
  --color-bg: hsl(220, 20%, 12%);
  --color-bg-alt: hsl(220, 20%, 16%);
  --color-border: hsl(220, 20%, 25%);
  --color-header-bg: rgba(30, 35, 45, 0.95);

  --shadow-sm: 0 1px 2px 0 rgba(0, 0, 0, 0.3);
  --shadow-md: 0 4px 6px -1px rgba(0, 0, 0, 0.4), 0 2px 4px -1px rgba(0, 0, 0, 0.2);
  --shadow-lg: 0 10px 15px -3px rgba(0, 0, 0, 0.4), 0 4px 6px -2px rgba(0, 0, 0, 0.2);
  --shadow-xl: 0 20px 25px -5px rgba(0, 0, 0, 0.4), 0 10px 10px -5px rgba(0, 0, 0, 0.2);
}

/* ============================================
   Theme Toggle & Back to Top
   ============================================ */
.theme-toggle {
  background: none;
  border: none;
  color: var(--color-text);
  cursor: pointer;
  padding: var(--space-2);
  border-radius: 50%;
  display: flex;
  align-items: center;
  justify-content: center;
  transition: background-color var(--transition-fast), color var(--transition-fast);
}

.theme-toggle:hover {
  background-color: var(--color-bg-alt);
  color: var(--color-primary);
}

.back-to-top {
  position: fixed;
  bottom: var(--space-8);
  right: var(--space-8);
  width: 48px;
  height: 48px;
  background-color: var(--color-primary);
  color: white;
  border: none;
  border-radius: 50%;
  box-shadow: var(--shadow-lg);
  cursor: pointer;
  display: flex;
  align-items: center;
  justify-content: center;
  opacity: 0;
  visibility: hidden;
  transform: translateY(20px);
  transition: all var(--transition-base);
  z-index: 900;
}

.back-to-top.visible {
  opacity: 1;
  visibility: visible;
  transform: translateY(0);
}

.back-to-top:hover {
  background-color: var(--color-primary-dark);
  transform: translateY(-4px);
}

/* ============================================
   Google Fonts Import
   ============================================ */
@import url('https://fonts.googleapis.com/css2?family=Inter:wght@300;400;500;600;700&display=swap');

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

html {
  scroll-behavior: smooth;
  -webkit-font-smoothing: antialiased;
  -moz-osx-font-smoothing: grayscale;
}

body {
  font-family: var(--font-sans);
  font-size: var(--text-base);
  line-height: 1.6;
  color: var(--color-text);
  background-color: var(--color-bg);
  overflow-x: hidden;
}

/* ============================================
   Typography
   ============================================ */
h1,
h2,
h3,
h4,
h5,
h6 {
  font-weight: var(--font-bold);
  line-height: 1.2;
  margin-bottom: var(--space-4);
  color: var(--color-text);
}

h1 {
  font-size: var(--text-5xl);
  font-weight: var(--font-bold);
}

h2 {
  font-size: var(--text-3xl);
  font-weight: var(--font-bold);
  position: relative;
  padding-bottom: var(--space-3);
  margin-bottom: var(--space-8);
}

h2::after {
  content: '';
  position: absolute;
  bottom: 0;
  left: 0;
  width: 60px;
  height: 4px;
  background: linear-gradient(90deg, var(--color-primary), var(--color-accent));
  border-radius: 2px;
}

h3 {
  font-size: var(--text-xl);
  font-weight: var(--font-semibold);
}

p {
  margin-bottom: var(--space-4);
}

a {
  color: var(--color-primary);
  text-decoration: none;
  transition: color var(--transition-fast);
}

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

a:focus {
  outline: 2px solid var(--color-primary);
  outline-offset: 2px;
  border-radius: 2px;
}

code {
  font-family: var(--font-mono);
  font-size: var(--text-sm);
  background-color: var(--color-bg-alt);
  padding: var(--space-1) var(--space-2);
  border-radius: 4px;
  border: 1px solid var(--color-border);
}

/* ============================================
   Layout Components
   ============================================ */
.container {
  max-width: var(--container-width);
  margin: 0 auto;
  padding: 0 var(--container-padding);
}

.section {
  padding: var(--space-20) 0;
}

.section:nth-child(even) {
  background-color: var(--color-bg-alt);
}

/* ============================================
   Header & Navigation
   ============================================ */
.site-header {
  background-color: var(--color-header-bg);
  backdrop-filter: blur(10px);
  border-bottom: 1px solid var(--color-border);
  position: sticky;
  top: 0;
  z-index: 1000;
  transition: box-shadow var(--transition-base);
}

.site-header.scrolled {
  box-shadow: var(--shadow-md);
}

.site-header nav {
  display: flex;
  align-items: center;
  justify-content: space-between;
  padding: var(--space-4) var(--container-padding);
}

.brand {
  font-size: var(--text-xl);
  font-weight: var(--font-bold);
  color: var(--color-text);
  transition: color var(--transition-fast);
}

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

.nav-links {
  display: flex;
  gap: var(--space-8);
}

.nav-links a {
  font-weight: var(--font-medium);
  color: var(--color-text-muted);
  position: relative;
  transition: color var(--transition-fast);
}

.nav-links a::after {
  content: '';
  position: absolute;
  bottom: -4px;
  left: 0;
  width: 0;
  height: 2px;
  background-color: var(--color-primary);
  transition: width var(--transition-base);
}

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

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

/* ============================================
   Hero Section
   ============================================ */
.hero {
  padding: var(--space-20) var(--container-padding);
  text-align: center;
  background: linear-gradient(135deg, var(--color-primary-light) 0%, var(--color-accent-light) 100%);
  position: relative;
  overflow: hidden;
}

.hero::before {
  content: '';
  position: absolute;
  top: -50%;
  right: -20%;
  width: 600px;
  height: 600px;
  background: radial-gradient(circle, rgba(99, 102, 241, 0.1) 0%, transparent 70%);
  animation: float 20s ease-in-out infinite;
}

.hero::after {
  content: '';
  position: absolute;
  bottom: -30%;
  left: -10%;
  width: 400px;
  height: 400px;
  background: radial-gradient(circle, rgba(168, 85, 247, 0.1) 0%, transparent 70%);
  animation: float 15s ease-in-out infinite reverse;
}

@keyframes float {

  0%,
  100% {
    transform: translateY(0) rotate(0deg);
  }

  50% {
    transform: translateY(-20px) rotate(5deg);
  }
}

.hero h1 {
  position: relative;
  z-index: 1;
  margin-bottom: var(--space-6);
  animation: fadeInUp 0.8s ease-out;
}

.hero p {
  position: relative;
  z-index: 1;
  font-size: var(--text-lg);
  color: var(--color-text-muted);
  max-width: 700px;
  margin: 0 auto var(--space-8);
  animation: fadeInUp 0.8s ease-out 0.2s backwards;
}

.accent {
  background: linear-gradient(135deg, var(--color-primary), var(--color-accent));
  -webkit-background-clip: text;
  -webkit-text-fill-color: transparent;
  background-clip: text;
}

@keyframes fadeInUp {
  from {
    opacity: 0;
    transform: translateY(30px);
  }

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

/* ============================================
   Buttons
   ============================================ */
.btn {
  display: inline-block;
  padding: var(--space-3) var(--space-6);
  font-weight: var(--font-semibold);
  font-size: var(--text-base);
  text-align: center;
  border-radius: var(--border-radius);
  transition: all var(--transition-base);
  cursor: pointer;
  border: 2px solid var(--color-primary);
  background-color: var(--color-primary);
  color: white;
  position: relative;
  overflow: hidden;
  z-index: 1;
}

.btn::before {
  content: '';
  position: absolute;
  top: 0;
  left: -100%;
  width: 100%;
  height: 100%;
  background: linear-gradient(90deg, transparent, rgba(255, 255, 255, 0.2), transparent);
  transition: left var(--transition-slow);
  z-index: -1;
}

.btn:hover::before {
  left: 100%;
}

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

.btn:active {
  transform: translateY(0);
}

.btn.ghost {
  background-color: transparent;
  color: var(--color-primary);
  border: 2px solid var(--color-primary);
  margin-left: var(--space-4);
}


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

.btn.btn-sm {
  padding: var(--space-2) var(--space-4);
  font-size: var(--text-sm);
  display: inline-flex;
  align-items: center;
  justify-content: center;
}

/* ============================================
   Project Links
   ============================================ */
.project-links {
  margin-top: var(--space-6);
  padding-top: var(--space-4);
  border-top: 1px solid var(--color-border);
}

.card .project-links {
  margin-bottom: 0;
}

.project-links .btn {
  margin: 0;
}

/* ============================================
   Grid System
   ============================================ */
.grid {
  display: grid;
  gap: var(--space-6);
  grid-template-columns: repeat(auto-fit, minmax(300px, 1fr));
}

.research-grid {
  grid-template-columns: repeat(auto-fit, minmax(300px, 1fr));
}

/* ============================================
   Cards
   ============================================ */
.card {
  background-color: var(--color-bg);
  border: 1px solid var(--color-border);
  border-radius: var(--border-radius-lg);
  padding: var(--space-6);
  transition: all var(--transition-base);
  position: relative;
  overflow: hidden;
}

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

.card:hover {
  transform: translateY(-4px);
  box-shadow: var(--shadow-xl);
  border-color: var(--color-primary);
}

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

.card h3 {
  color: var(--color-text);
  margin-bottom: var(--space-3);
  font-size: var(--text-lg);
}

.card p {
  color: var(--color-text-muted);
  line-height: 1.6;
  font-size: var(--text-sm);
}

/* ============================================
   Research Cards
   ============================================ */
.research-card {
  display: flex;
  flex-direction: column;
}

.research-head {
  margin-bottom: var(--space-4);
}

.research-head h3 {
  margin-bottom: var(--space-1);
}

.meta {
  font-size: var(--text-xs);
  color: var(--color-text-muted);
  font-weight: var(--font-medium);
}

.thumbs {
  margin: var(--space-4) 0;
  border-radius: var(--border-radius);
  overflow: hidden;
}

.thumbs img {
  width: 100%;
  height: auto;
  display: block;
  transition: transform var(--transition-slow);
}

.thumbs a:hover img {
  transform: scale(1.05);
}

.blurb {
  flex: 1;
  margin-bottom: var(--space-6);
}

.actions {
  display: flex;
  gap: var(--space-4);
  margin-top: auto;
}

/* ============================================
   Publications
   ============================================ */
.pub-list {
  list-style: none;
  counter-reset: pub-counter;
}

.pub {
  padding: var(--space-6);
  margin-bottom: var(--space-6);
  background-color: var(--color-bg);
  border-left: 4px solid var(--color-primary);
  border-radius: var(--border-radius);
  transition: all var(--transition-base);
  position: relative;
}

.pub:hover {
  background-color: var(--color-bg-alt);
  transform: translateX(8px);
  box-shadow: var(--shadow-md);
}

.pub .key {
  display: inline-block;
  font-weight: var(--font-bold);
  color: var(--color-primary);
  margin-right: var(--space-3);
  font-family: var(--font-mono);
  font-size: var(--text-sm);
}

.pub .authors {
  font-weight: var(--font-medium);
  color: var(--color-text);
}

.pub .title {
  font-style: italic;
  color: var(--color-text);
  font-weight: var(--font-semibold);
}

.pub .venue {
  color: var(--color-text-muted);
}

/* ============================================
   Visitor Analytics
   ============================================ */
#visitor-map {
  margin: var(--space-4) auto;
  text-align: center;
  max-width: 300px;
  /* Keep it small and unobtrusive */
  min-height: 100px;
  /* Placeholder height */
  overflow: hidden;
}

.pub .vol {
  font-weight: var(--font-semibold);
}

.pub .links {
  margin-left: var(--space-4);
}

.pub .links a {
  display: inline-block;
  padding: var(--space-1) var(--space-3);
  background-color: var(--color-primary-light);
  color: var(--color-primary);
  border-radius: var(--border-radius);
  font-size: var(--text-sm);
  font-weight: var(--font-semibold);
  transition: all var(--transition-fast);
  margin-right: var(--space-2);
}

.pub .links a:hover {
  background-color: var(--color-primary);
  color: white;
  transform: translateY(-2px);
}

/* ============================================
   Highlights Section
   ============================================ */
.highlight-wrapper {
  max-width: 900px;
  margin: 0 auto;
}

.highlight-figure {
  text-align: center;
  margin: 0;
  padding: var(--space-6);
  background-color: var(--color-bg);
  border: 1px solid var(--color-border);
  border-radius: var(--border-radius-lg);
  transition: all var(--transition-base);
}

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

.highlight-figure img {
  max-width: 600px;
  width: 100%;
  height: auto;
  border-radius: var(--border-radius);
  display: block;
  margin: 0 auto var(--space-4);
}

.highlight-figure figcaption {
  color: var(--color-text-muted);
  font-size: var(--text-sm);
  font-style: italic;
  line-height: 1.5;
  margin-top: var(--space-4);
}

/* ============================================
   Contact Section
   ============================================ */
.contact-list {
  list-style: none;
  display: flex;
  flex-direction: column;
  gap: var(--space-2);
}

.contact-list li {
  font-size: var(--text-base);
}

.contact-list a {
  display: inline-flex;
  align-items: center;
  padding: var(--space-3) var(--space-5);
  background-color: var(--color-bg-alt);
  border-radius: var(--border-radius);
  transition: all var(--transition-base);
  border: 2px solid transparent;
}

.contact-list a:hover {
  background-color: var(--color-primary-light);
  border-color: var(--color-primary);
  transform: translateX(8px);
}

/* ============================================
   Footer
   ============================================ */
.site-footer {
  background-color: var(--color-text);
  color: var(--color-bg-alt);
  padding: var(--space-8) 0;
  text-align: center;
  margin-top: var(--space-20);
}

.site-footer .container {
  font-size: var(--text-sm);
}

/* ============================================
   Responsive Design
   ============================================ */
@media (max-width: 768px) {
  :root {
    --text-5xl: 2rem;
    --text-3xl: 1.5rem;
    --text-xl: 1.125rem;
  }

  .nav-links {
    gap: var(--space-4);
  }

  .hero {
    padding: var(--space-12) var(--container-padding);
  }

  .section {
    padding: var(--space-12) 0;
  }

  .grid {
    grid-template-columns: 1fr;
  }

  .research-grid {
    grid-template-columns: 1fr;
  }

  .btn.ghost {
    margin-left: 0;
    margin-top: var(--space-3);
  }

  h2::after {
    width: 40px;
  }
}

@media (max-width: 480px) {
  .site-header nav {
    flex-direction: column;
    gap: var(--space-4);
  }

  .nav-links {
    flex-wrap: wrap;
    justify-content: center;
  }
}

/* ============================================
   Utility Classes
   ============================================ */
.text-center {
  text-align: center;
}

.mb-0 {
  margin-bottom: 0;
}

/* ============================================
   Animations & Micro-interactions
   ============================================ */
@media (prefers-reduced-motion: reduce) {

  *,
  *::before,
  *::after {
    animation-duration: 0.01ms !important;
    animation-iteration-count: 1 !important;
    transition-duration: 0.01ms !important;
    scroll-behavior: auto !important;
  }
}

/* ============================================
   Tabs
   ============================================ */
.tab-nav {
  display: flex;
  justify-content: center;
  gap: var(--space-4);
  margin-bottom: var(--space-8);
  border-bottom: 1px solid var(--color-border);
}

.tab-btn {
  background: none;
  border: none;
  border-bottom: 3px solid transparent;
  padding: var(--space-2) var(--space-4);
  font-size: var(--text-base);
  font-weight: var(--font-semibold);
  color: var(--color-text-muted);
  cursor: pointer;
  transition: all 0.2s;
}

.tab-btn:hover {
  color: var(--color-text);
}

.tab-btn.active {
  color: var(--color-primary);
  border-bottom-color: var(--color-primary);
}

.tab-content {
  display: none;
  animation: fadeIn 0.3s ease;
}

.tab-content.active {
  display: block;
}

@keyframes fadeIn {
  from {
    opacity: 0;
    transform: translateY(10px);
  }

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

/* ============================================
   Game Section
   ============================================ */
.game-container {
  background: var(--color-bg);
  border: 1px solid var(--color-border);
  border-radius: var(--border-radius-lg);
  padding: var(--space-4);
  box-shadow: var(--shadow-lg);
  display: flex;
  flex-direction: column;
  gap: var(--space-4);
}

#game-canvas {
  width: 100%;
  height: 500px;
  /* Force height */
  background-color: var(--color-bg-alt);
  border-radius: var(--border-radius);
  cursor: crosshair;
  border: 1px solid var(--color-border);
}

.controls {
  display: flex;
  flex-wrap: wrap;
  gap: var(--space-4);
  align-items: center;
  justify-content: center;
}

.control-group {
  display: flex;
  align-items: center;
  gap: var(--space-2);
}

.stats {
  display: flex;
  justify-content: space-around;
  font-family: var(--font-mono);
  font-size: var(--text-sm);
  color: var(--color-text-muted);
}

/* Loading state for images */
img {
  transition: opacity var(--transition-base);
}

img[loading="lazy"] {
  opacity: 0;
}

img[loading="lazy"].loaded {
  opacity: 1;
}

/* Focus visible for accessibility */
*:focus-visible {
  outline: 2px solid var(--color-primary);
  outline-offset: 2px;
}