:root {
  /* Neon Cyberpunk Palette */
  --neon-cyan: #00f5ff;
  --neon-magenta: #ff00ff;
  --neon-purple: #bf00ff;
  --neon-blue: #4d4dff;
  --neon-green: #00ff9f;

  --primary: #00f5ff;
  --primary-dark: #00c4cc;
  --secondary: #ff00ff;
  --accent: #bf00ff;

  --bg: #0a0a0f;
  --bg-light: #12121a;
  --bg-card: rgba(18, 18, 26, 0.8);
  --text: #e8e8ff;
  --text-muted: #8888aa;
  --border: rgba(0, 245, 255, 0.15);
  --border-glow: rgba(0, 245, 255, 0.3);

  --success: #00ff9f;
  --error: #ff3366;
  --warning: #ffaa00;

  /* Glow intensities */
  --glow-sm: 0 0 10px;
  --glow-md: 0 0 20px;
  --glow-lg: 0 0 40px;
}

* {
  margin: 0;
  padding: 0;
  box-sizing: border-box;
}

/* Animated Background */
body {
  font-family: 'Inter', -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, sans-serif;
  background: var(--bg);
  color: var(--text);
  line-height: 1.6;
  min-height: 100vh;
  position: relative;
  overflow-x: hidden;
}

body::before {
  content: '';
  position: fixed;
  top: 0;
  left: 0;
  width: 100%;
  height: 100%;
  background:
    radial-gradient(ellipse at 20% 20%, rgba(0, 245, 255, 0.08) 0%, transparent 50%),
    radial-gradient(ellipse at 80% 80%, rgba(255, 0, 255, 0.08) 0%, transparent 50%),
    radial-gradient(ellipse at 50% 50%, rgba(191, 0, 255, 0.05) 0%, transparent 60%);
  pointer-events: none;
  z-index: 0;
  animation: backgroundPulse 8s ease-in-out infinite alternate;
}

@keyframes backgroundPulse {
  0% { opacity: 0.6; }
  100% { opacity: 1; }
}

/* Grid overlay effect */
body::after {
  content: '';
  position: fixed;
  top: 0;
  left: 0;
  width: 100%;
  height: 100%;
  background-image:
    linear-gradient(rgba(0, 245, 255, 0.03) 1px, transparent 1px),
    linear-gradient(90deg, rgba(0, 245, 255, 0.03) 1px, transparent 1px);
  background-size: 50px 50px;
  pointer-events: none;
  z-index: 0;
}

.container {
  max-width: 900px;
  margin: 0 auto;
  padding: 2rem;
  position: relative;
  z-index: 1;
}

/* Navigation */
nav {
  background: rgba(10, 10, 15, 0.9);
  backdrop-filter: blur(20px);
  -webkit-backdrop-filter: blur(20px);
  border-bottom: 1px solid var(--border);
  padding: 1rem 2rem;
  position: sticky;
  top: 0;
  z-index: 100;
  box-shadow: 0 0 30px rgba(0, 245, 255, 0.1);
}

nav .nav-content {
  max-width: 900px;
  margin: 0 auto;
  display: flex;
  justify-content: space-between;
  align-items: center;
}

nav .logo {
  font-size: 1.25rem;
  font-weight: 700;
  background: linear-gradient(135deg, var(--neon-cyan), var(--neon-magenta));
  -webkit-background-clip: text;
  -webkit-text-fill-color: transparent;
  background-clip: text;
  text-decoration: none;
  text-shadow: 0 0 30px rgba(0, 245, 255, 0.5);
  transition: all 0.3s ease;
}

nav .logo:hover {
  filter: brightness(1.2);
}

nav .nav-links {
  display: flex;
  gap: 1.5rem;
  list-style: none;
}

nav .nav-links a {
  color: var(--text-muted);
  text-decoration: none;
  transition: all 0.3s ease;
  position: relative;
  padding: 0.5rem 0;
}

nav .nav-links a::after {
  content: '';
  position: absolute;
  bottom: 0;
  left: 0;
  width: 0;
  height: 2px;
  background: linear-gradient(90deg, var(--neon-cyan), var(--neon-magenta));
  transition: width 0.3s ease;
  box-shadow: var(--glow-sm) var(--neon-cyan);
}

nav .nav-links a:hover,
nav .nav-links a.active {
  color: var(--neon-cyan);
  text-shadow: var(--glow-sm) var(--neon-cyan);
}

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

/* Typography */
h1, h2, h3 {
  color: var(--text);
  margin-bottom: 1rem;
}

h1 {
  font-size: 2.5rem;
  background: linear-gradient(135deg, var(--neon-cyan) 0%, var(--neon-magenta) 50%, var(--neon-purple) 100%);
  -webkit-background-clip: text;
  -webkit-text-fill-color: transparent;
  background-clip: text;
  animation: gradientShift 3s ease infinite;
  background-size: 200% 200%;
}

@keyframes gradientShift {
  0%, 100% { background-position: 0% 50%; }
  50% { background-position: 100% 50%; }
}

h2 {
  font-size: 1.75rem;
  margin-top: 2rem;
  color: var(--neon-cyan);
  text-shadow: var(--glow-sm) rgba(0, 245, 255, 0.3);
}

h3 {
  font-size: 1.25rem;
}

p {
  margin-bottom: 1rem;
  color: var(--text-muted);
}

/* Buttons */
.btn {
  display: inline-block;
  padding: 0.75rem 1.5rem;
  border-radius: 8px;
  font-weight: 600;
  text-decoration: none;
  cursor: pointer;
  border: none;
  transition: all 0.3s ease;
  font-size: 1rem;
  position: relative;
  overflow: hidden;
}

.btn-primary {
  background: linear-gradient(135deg, var(--neon-cyan), var(--neon-blue));
  color: var(--bg);
  box-shadow:
    0 0 20px rgba(0, 245, 255, 0.4),
    inset 0 0 20px rgba(255, 255, 255, 0.1);
}

.btn-primary:hover {
  transform: translateY(-3px);
  box-shadow:
    0 0 30px rgba(0, 245, 255, 0.6),
    0 0 60px rgba(0, 245, 255, 0.3),
    inset 0 0 20px rgba(255, 255, 255, 0.2);
}

.btn-primary::before {
  content: '';
  position: absolute;
  top: 0;
  left: -100%;
  width: 100%;
  height: 100%;
  background: linear-gradient(90deg, transparent, rgba(255, 255, 255, 0.3), transparent);
  transition: left 0.5s ease;
}

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

.btn-secondary {
  background: transparent;
  color: var(--neon-cyan);
  border: 2px solid var(--neon-cyan);
  box-shadow: 0 0 10px rgba(0, 245, 255, 0.2);
}

.btn-secondary:hover {
  background: rgba(0, 245, 255, 0.1);
  box-shadow:
    0 0 20px rgba(0, 245, 255, 0.4),
    inset 0 0 20px rgba(0, 245, 255, 0.1);
  transform: translateY(-2px);
}

.btn-small {
  padding: 0.5rem 1rem;
  font-size: 0.875rem;
}

.btn:disabled {
  opacity: 0.5;
  cursor: not-allowed;
  transform: none;
  box-shadow: none;
}

/* Cards */
.card {
  background: var(--bg-card);
  backdrop-filter: blur(10px);
  -webkit-backdrop-filter: blur(10px);
  border: 1px solid var(--border);
  border-radius: 12px;
  padding: 1.5rem;
  margin-bottom: 1rem;
  transition: all 0.3s ease;
  position: relative;
}

.card::before {
  content: '';
  position: absolute;
  inset: 0;
  border-radius: 12px;
  padding: 1px;
  background: linear-gradient(135deg, rgba(0, 245, 255, 0.3), transparent, rgba(255, 0, 255, 0.3));
  -webkit-mask: linear-gradient(#fff 0 0) content-box, linear-gradient(#fff 0 0);
  mask: linear-gradient(#fff 0 0) content-box, linear-gradient(#fff 0 0);
  -webkit-mask-composite: xor;
  mask-composite: exclude;
  pointer-events: none;
  opacity: 0;
  transition: opacity 0.3s ease;
}

.card:hover::before {
  opacity: 1;
}

.card:hover {
  box-shadow:
    0 0 30px rgba(0, 245, 255, 0.15),
    0 10px 40px rgba(0, 0, 0, 0.3);
  transform: translateY(-2px);
}

.card-grid {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(250px, 1fr));
  gap: 1rem;
  margin: 2rem 0;
}

/* Interactive Canvas Container */
.canvas-container {
  background: var(--bg-card);
  backdrop-filter: blur(10px);
  border: 1px solid var(--border);
  border-radius: 12px;
  padding: 1rem;
  margin: 2rem 0;
  box-shadow: 0 0 30px rgba(0, 245, 255, 0.1);
}

canvas {
  display: block;
  margin: 0 auto;
  border-radius: 8px;
}

/* Controls */
.controls {
  display: flex;
  gap: 1rem;
  justify-content: center;
  margin-top: 1rem;
  flex-wrap: wrap;
}

/* Input Groups */
.input-group {
  display: flex;
  align-items: center;
  gap: 0.5rem;
  margin: 0.5rem 0;
}

.input-group label {
  color: var(--text-muted);
  min-width: 80px;
}

.input-group input,
.input-group select {
  background: var(--bg);
  border: 1px solid var(--border);
  border-radius: 6px;
  padding: 0.5rem 0.75rem;
  color: var(--text);
  font-size: 1rem;
  width: 120px;
  transition: all 0.3s ease;
}

.input-group input:focus,
.input-group select:focus {
  outline: none;
  border-color: var(--neon-cyan);
  box-shadow: 0 0 15px rgba(0, 245, 255, 0.3);
}

.input-group input[type="number"] {
  font-family: 'Monaco', 'Menlo', 'Ubuntu Mono', monospace;
}

/* Stats Display */
.stats {
  display: flex;
  gap: 2rem;
  justify-content: center;
  margin: 1rem 0;
  flex-wrap: wrap;
}

.stat {
  text-align: center;
}

.stat-value {
  font-size: 2rem;
  font-weight: 700;
  color: var(--neon-cyan);
  text-shadow: var(--glow-md) rgba(0, 245, 255, 0.5);
}

.stat-label {
  font-size: 0.875rem;
  color: var(--text-muted);
}

/* Code Blocks */
.code-block {
  background: rgba(0, 0, 0, 0.5);
  border: 1px solid var(--border);
  border-radius: 8px;
  padding: 1rem;
  overflow-x: auto;
  margin: 1rem 0;
  position: relative;
}

.code-block::before {
  content: '';
  position: absolute;
  top: 0;
  left: 0;
  width: 3px;
  height: 100%;
  background: linear-gradient(180deg, var(--neon-cyan), var(--neon-magenta));
  border-radius: 8px 0 0 8px;
}

.code-block code {
  font-family: 'Monaco', 'Menlo', 'Ubuntu Mono', monospace;
  font-size: 0.875rem;
  color: var(--neon-green);
}

/* Math Display */
.math {
  font-family: 'Times New Roman', Georgia, serif;
  font-size: 1.1em;
  font-style: italic;
  color: var(--neon-cyan);
}

.math-block {
  background: var(--bg-card);
  border: 1px solid var(--border);
  border-radius: 8px;
  padding: 1.5rem;
  margin: 1.5rem 0;
  text-align: center;
  font-family: 'Times New Roman', Georgia, serif;
  font-size: 1.25rem;
  box-shadow: 0 0 20px rgba(0, 245, 255, 0.1);
}

/* Step-by-step Display */
.steps-container {
  background: var(--bg-card);
  border: 1px solid var(--border);
  border-radius: 8px;
  padding: 1rem;
  margin: 1rem 0;
  font-family: 'Monaco', 'Menlo', 'Ubuntu Mono', monospace;
  font-size: 0.9rem;
}

.step {
  padding: 0.5rem 0;
  border-bottom: 1px solid var(--border);
  display: flex;
  align-items: center;
  gap: 0.5rem;
  transition: all 0.3s ease;
}

.step:last-child {
  border-bottom: none;
}

.step-number {
  background: linear-gradient(135deg, var(--neon-cyan), var(--neon-blue));
  color: var(--bg);
  width: 24px;
  height: 24px;
  border-radius: 50%;
  display: flex;
  align-items: center;
  justify-content: center;
  font-size: 0.75rem;
  font-weight: 700;
  flex-shrink: 0;
  box-shadow: 0 0 10px rgba(0, 245, 255, 0.4);
}

.step.highlight {
  background: rgba(0, 245, 255, 0.1);
  margin: 0 -1rem;
  padding: 0.5rem 1rem;
  box-shadow: inset 0 0 20px rgba(0, 245, 255, 0.1);
}

.step-result {
  color: var(--neon-green);
  font-weight: 700;
  text-shadow: var(--glow-sm) rgba(0, 255, 159, 0.5);
}

/* Number Grid (for sieves, totient viz, etc.) */
.number-grid {
  display: grid;
  grid-template-columns: repeat(10, 1fr);
  gap: 4px;
  margin: 1rem 0;
}

.number-cell {
  aspect-ratio: 1;
  display: flex;
  align-items: center;
  justify-content: center;
  background: var(--bg-card);
  border: 1px solid var(--border);
  border-radius: 4px;
  font-size: 0.875rem;
  font-weight: 500;
  transition: all 0.3s ease;
}

.number-cell.prime {
  background: rgba(0, 255, 159, 0.2);
  color: var(--neon-green);
  border-color: var(--neon-green);
  box-shadow: 0 0 10px rgba(0, 255, 159, 0.3);
}

.number-cell.composite {
  background: rgba(255, 51, 102, 0.2);
  color: var(--error);
  border-color: var(--error);
  opacity: 0.6;
}

.number-cell.coprime {
  background: rgba(0, 255, 159, 0.2);
  color: var(--neon-green);
  border-color: var(--neon-green);
  box-shadow: 0 0 10px rgba(0, 255, 159, 0.3);
}

.number-cell.not-coprime {
  background: var(--bg);
  color: var(--text-muted);
  opacity: 0.5;
}

.number-cell.current {
  box-shadow: 0 0 20px var(--warning), inset 0 0 10px rgba(255, 170, 0, 0.2);
  border-color: var(--warning);
}

/* Demo Section */
.demo-section {
  background: var(--bg-card);
  backdrop-filter: blur(10px);
  border: 1px solid var(--border);
  border-radius: 12px;
  padding: 1.5rem;
  margin: 2rem 0;
  position: relative;
  overflow: hidden;
}

.demo-section::before {
  content: '';
  position: absolute;
  top: 0;
  left: 0;
  width: 100%;
  height: 3px;
  background: linear-gradient(90deg, var(--neon-cyan), var(--neon-magenta), var(--neon-purple));
}

.demo-section h3 {
  margin-top: 0;
  margin-bottom: 1rem;
}

/* Output Panel */
.output-panel {
  background: rgba(0, 0, 0, 0.5);
  border: 1px solid var(--border);
  border-radius: 8px;
  padding: 1rem;
  margin-top: 1rem;
  font-family: 'Monaco', 'Menlo', 'Ubuntu Mono', monospace;
  font-size: 0.875rem;
  min-height: 60px;
  white-space: pre-wrap;
  word-break: break-all;
}

.output-panel .success {
  color: var(--neon-green);
  text-shadow: var(--glow-sm) rgba(0, 255, 159, 0.5);
}

.output-panel .error {
  color: var(--error);
  text-shadow: var(--glow-sm) rgba(255, 51, 102, 0.5);
}

.output-panel .muted {
  color: var(--text-muted);
}

/* Playground */
.playground {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: 1rem;
  margin: 2rem 0;
}

.playground textarea {
  width: 100%;
  min-height: 200px;
  background: rgba(0, 0, 0, 0.5);
  color: var(--neon-green);
  border: 1px solid var(--border);
  border-radius: 8px;
  padding: 1rem;
  font-family: 'Monaco', 'Menlo', 'Ubuntu Mono', monospace;
  font-size: 0.875rem;
  resize: vertical;
  transition: all 0.3s ease;
}

.playground textarea:focus {
  outline: none;
  border-color: var(--neon-cyan);
  box-shadow: 0 0 20px rgba(0, 245, 255, 0.2);
}

.playground-output {
  background: var(--bg-card);
  border: 1px solid var(--border);
  border-radius: 8px;
  padding: 1rem;
  font-family: 'Monaco', 'Menlo', 'Ubuntu Mono', monospace;
  font-size: 0.875rem;
  white-space: pre-wrap;
}

/* Quiz */
.quiz-question {
  background: var(--bg-card);
  backdrop-filter: blur(10px);
  border: 1px solid var(--border);
  border-radius: 12px;
  padding: 1.5rem;
  margin: 1rem 0;
}

.quiz-options {
  display: flex;
  flex-direction: column;
  gap: 0.5rem;
  margin-top: 1rem;
}

.quiz-option {
  padding: 1rem;
  background: var(--bg);
  border: 2px solid var(--border);
  border-radius: 8px;
  cursor: pointer;
  transition: all 0.3s ease;
}

.quiz-option:hover {
  border-color: var(--neon-cyan);
  box-shadow: 0 0 15px rgba(0, 245, 255, 0.2);
}

.quiz-option.selected {
  border-color: var(--neon-cyan);
  background: rgba(0, 245, 255, 0.1);
  box-shadow: 0 0 20px rgba(0, 245, 255, 0.2);
}

.quiz-option.correct {
  border-color: var(--neon-green);
  background: rgba(0, 255, 159, 0.1);
  box-shadow: 0 0 20px rgba(0, 255, 159, 0.3);
}

.quiz-option.incorrect {
  border-color: var(--error);
  background: rgba(255, 51, 102, 0.1);
  box-shadow: 0 0 20px rgba(255, 51, 102, 0.3);
}

.quiz-feedback {
  margin-top: 1rem;
  padding: 1rem;
  border-radius: 8px;
  display: none;
}

.quiz-feedback.show {
  display: block;
}

.quiz-feedback.correct {
  background: rgba(0, 255, 159, 0.1);
  border: 1px solid var(--neon-green);
  box-shadow: 0 0 15px rgba(0, 255, 159, 0.2);
}

.quiz-feedback.incorrect {
  background: rgba(255, 51, 102, 0.1);
  border: 1px solid var(--error);
  box-shadow: 0 0 15px rgba(255, 51, 102, 0.2);
}

/* Progress Bar */
.progress-bar {
  background: var(--bg);
  border-radius: 999px;
  height: 8px;
  overflow: hidden;
  margin: 1rem 0;
  box-shadow: inset 0 0 10px rgba(0, 0, 0, 0.5);
}

.progress-fill {
  background: linear-gradient(90deg, var(--neon-cyan), var(--neon-magenta));
  height: 100%;
  transition: width 0.3s ease;
  box-shadow: 0 0 15px rgba(0, 245, 255, 0.5);
  position: relative;
}

.progress-fill::after {
  content: '';
  position: absolute;
  top: 0;
  left: 0;
  right: 0;
  bottom: 0;
  background: linear-gradient(90deg, transparent, rgba(255, 255, 255, 0.3), transparent);
  animation: progressShine 2s infinite;
}

@keyframes progressShine {
  0% { transform: translateX(-100%); }
  100% { transform: translateX(100%); }
}

/* Page Navigation */
.page-nav {
  display: flex;
  justify-content: space-between;
  margin-top: 3rem;
  padding-top: 2rem;
  border-top: 1px solid var(--border);
}

/* Hero Section */
.hero {
  text-align: center;
  padding: 4rem 0;
  position: relative;
}

.hero h1 {
  font-size: 3.5rem;
  margin-bottom: 1.5rem;
  text-shadow:
    0 0 20px rgba(0, 245, 255, 0.5),
    0 0 40px rgba(255, 0, 255, 0.3),
    0 0 60px rgba(191, 0, 255, 0.2);
}

.hero p {
  font-size: 1.25rem;
  max-width: 600px;
  margin: 0 auto 2rem;
  color: var(--text-muted);
}

/* Lesson List */
.lesson-list {
  list-style: none;
}

.lesson-item {
  display: flex;
  align-items: center;
  gap: 1rem;
  padding: 1rem;
  background: var(--bg-card);
  backdrop-filter: blur(10px);
  border: 1px solid var(--border);
  border-radius: 8px;
  margin-bottom: 0.5rem;
  text-decoration: none;
  color: var(--text);
  transition: all 0.3s ease;
  position: relative;
  overflow: hidden;
}

.lesson-item::before {
  content: '';
  position: absolute;
  left: 0;
  top: 0;
  height: 100%;
  width: 3px;
  background: linear-gradient(180deg, var(--neon-cyan), var(--neon-magenta));
  opacity: 0;
  transition: opacity 0.3s ease;
}

.lesson-item:hover {
  border-color: var(--neon-cyan);
  transform: translateX(8px);
  box-shadow:
    0 0 20px rgba(0, 245, 255, 0.2),
    -5px 0 30px rgba(0, 245, 255, 0.1);
}

.lesson-item:hover::before {
  opacity: 1;
}

.lesson-number {
  width: 40px;
  height: 40px;
  background: linear-gradient(135deg, var(--neon-cyan), var(--neon-blue));
  border-radius: 50%;
  display: flex;
  align-items: center;
  justify-content: center;
  font-weight: 700;
  flex-shrink: 0;
  box-shadow: 0 0 15px rgba(0, 245, 255, 0.4);
  color: var(--bg);
}

.lesson-info h3 {
  margin-bottom: 0.25rem;
  font-size: 1rem;
  transition: color 0.3s ease;
}

.lesson-item:hover .lesson-info h3 {
  color: var(--neon-cyan);
}

.lesson-info p {
  margin: 0;
  font-size: 0.875rem;
}

/* Module Headers */
.module-header {
  color: var(--neon-magenta);
  font-size: 0.75rem;
  text-transform: uppercase;
  letter-spacing: 0.2em;
  margin: 2rem 0 1rem;
  padding-bottom: 0.5rem;
  border-bottom: 1px solid var(--border);
  text-shadow: var(--glow-sm) rgba(255, 0, 255, 0.5);
}

/* Callout Boxes */
.callout {
  padding: 1rem 1.5rem;
  border-radius: 8px;
  margin: 1.5rem 0;
  border-left: 4px solid;
  backdrop-filter: blur(10px);
}

.callout-info {
  background: rgba(0, 245, 255, 0.1);
  border-color: var(--neon-cyan);
  box-shadow: 0 0 20px rgba(0, 245, 255, 0.1);
}

.callout-success {
  background: rgba(0, 255, 159, 0.1);
  border-color: var(--neon-green);
  box-shadow: 0 0 20px rgba(0, 255, 159, 0.1);
}

.callout-warning {
  background: rgba(255, 170, 0, 0.1);
  border-color: var(--warning);
  box-shadow: 0 0 20px rgba(255, 170, 0, 0.1);
}

/* Table Styles */
.data-table {
  width: 100%;
  border-collapse: collapse;
  margin: 1rem 0;
  font-family: 'Monaco', 'Menlo', 'Ubuntu Mono', monospace;
  font-size: 0.875rem;
}

.data-table th,
.data-table td {
  padding: 0.75rem;
  text-align: center;
  border: 1px solid var(--border);
}

.data-table th {
  background: var(--bg-card);
  color: var(--neon-cyan);
  font-weight: 600;
  text-shadow: var(--glow-sm) rgba(0, 245, 255, 0.3);
}

.data-table td {
  background: var(--bg);
}

.data-table tr:hover td {
  background: var(--bg-card);
  box-shadow: inset 0 0 20px rgba(0, 245, 255, 0.05);
}

/* Animation Classes */
.fade-in {
  animation: fadeIn 0.5s ease-out;
}

@keyframes fadeIn {
  from {
    opacity: 0;
    transform: translateY(10px);
  }
  to {
    opacity: 1;
    transform: translateY(0);
  }
}

.pulse {
  animation: neonPulse 2s ease-in-out infinite;
}

@keyframes neonPulse {
  0%, 100% {
    box-shadow: 0 0 10px rgba(0, 245, 255, 0.4);
  }
  50% {
    box-shadow: 0 0 25px rgba(0, 245, 255, 0.6), 0 0 50px rgba(0, 245, 255, 0.3);
  }
}

/* Glowing text animation */
.glow-text {
  animation: textGlow 2s ease-in-out infinite alternate;
}

@keyframes textGlow {
  from {
    text-shadow: 0 0 10px rgba(0, 245, 255, 0.5), 0 0 20px rgba(0, 245, 255, 0.3);
  }
  to {
    text-shadow: 0 0 20px rgba(0, 245, 255, 0.8), 0 0 40px rgba(0, 245, 255, 0.5), 0 0 60px rgba(0, 245, 255, 0.3);
  }
}

/* Responsive */
@media (max-width: 768px) {
  .container {
    padding: 1rem;
  }

  .hero h1 {
    font-size: 2rem;
  }

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

  nav .nav-links {
    display: none;
  }

  .stats {
    gap: 1rem;
  }

  .number-grid {
    grid-template-columns: repeat(5, 1fr);
  }

  .input-group {
    flex-direction: column;
    align-items: stretch;
  }

  .input-group label {
    min-width: auto;
  }

  .input-group input {
    width: 100%;
  }

  body::after {
    background-size: 30px 30px;
  }
}

/* Selection styling */
::selection {
  background: rgba(0, 245, 255, 0.3);
  color: var(--text);
}

/* Scrollbar styling */
::-webkit-scrollbar {
  width: 8px;
  height: 8px;
}

::-webkit-scrollbar-track {
  background: var(--bg);
}

::-webkit-scrollbar-thumb {
  background: linear-gradient(180deg, var(--neon-cyan), var(--neon-magenta));
  border-radius: 4px;
}

::-webkit-scrollbar-thumb:hover {
  background: linear-gradient(180deg, var(--neon-magenta), var(--neon-cyan));
}