/* Modern IXL-Style Design System */

@import url('https://fonts.googleapis.com/css2?family=Poppins:wght@300;400;500;600;700;800&family=Inter:wght@300;400;500;600;700&display=swap');

:root {
  /* Primary Colors - Vibrant and Educational */
  --primary-purple: #8b5cf6;
  --primary-blue: #3b82f6;
  --primary-green: #10b981;
  --primary-orange: #f59e0b;
  --primary-pink: #ec4899;
  --primary-cyan: #06b6d4;
  
  /* Semantic Colors */
  --success: #10b981;
  --warning: #f59e0b;
  --error: #ef4444;
  --info: #3b82f6;
  
  /* Neutral Colors - Light Theme */
  --bg-primary: #ffffff;
  --bg-secondary: #f8fafc;
  --bg-tertiary: #f1f5f9;
  --text-primary: #1e293b;
  --text-secondary: #64748b;
  --text-tertiary: #94a3b8;
  --border-color: #e2e8f0;
  --shadow-sm: 0 1px 3px 0 rgba(0, 0, 0, 0.1);
  --shadow-md: 0 4px 6px -1px rgba(0, 0, 0, 0.1);
  --shadow-lg: 0 10px 15px -3px rgba(0, 0, 0, 0.1);
  --shadow-xl: 0 20px 25px -5px rgba(0, 0, 0, 0.1);
  
  /* Spacing */
  --space-xs: 0.25rem;
  --space-sm: 0.5rem;
  --space-md: 1rem;
  --space-lg: 1.5rem;
  --space-xl: 2rem;
  --space-2xl: 3rem;
  
  /* Border Radius */
  --radius-sm: 0.375rem;
  --radius-md: 0.5rem;
  --radius-lg: 0.75rem;
  --radius-xl: 1rem;
  --radius-2xl: 1.5rem;
  --radius-full: 9999px;
  
  /* Transitions */
  --transition-fast: 150ms cubic-bezier(0.4, 0, 0.2, 1);
  --transition-base: 300ms cubic-bezier(0.4, 0, 0.2, 1);
  --transition-slow: 500ms cubic-bezier(0.4, 0, 0.2, 1);
}

[data-theme="dark"] {
  --bg-primary: #0f172a;
  --bg-secondary: #1e293b;
  --bg-tertiary: #334155;
  --text-primary: #f1f5f9;
  --text-secondary: #cbd5e1;
  --text-tertiary: #94a3b8;
  --border-color: #334155;
  --shadow-sm: 0 1px 3px 0 rgba(0, 0, 0, 0.3);
  --shadow-md: 0 4px 6px -1px rgba(0, 0, 0, 0.4);
  --shadow-lg: 0 10px 15px -3px rgba(0, 0, 0, 0.5);
  --shadow-xl: 0 20px 25px -5px rgba(0, 0, 0, 0.6);
}

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

body {
  font-family: 'Inter', -apple-system, BlinkMacSystemFont, 'Segoe UI', sans-serif;
  background: var(--bg-secondary);
  color: var(--text-primary);
  line-height: 1.6;
  transition: background-color var(--transition-base), color var(--transition-base);
}

h1, h2, h3, h4, h5, h6 {
  font-family: 'Poppins', sans-serif;
  font-weight: 700;
  line-height: 1.2;
  color: var(--text-primary);
}

/* Modern Card Component */
.card {
  background: var(--bg-primary);
  border-radius: var(--radius-xl);
  padding: var(--space-xl);
  box-shadow: var(--shadow-md);
  border: 1px solid var(--border-color);
  transition: all var(--transition-base);
}

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

.card-compact {
  padding: var(--space-lg);
}

.card-interactive {
  cursor: pointer;
  position: relative;
  overflow: hidden;
}

.card-interactive::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 0.5s;
}

.card-interactive:hover::before {
  left: 100%;
}

/* Badge Component */
.badge {
  display: inline-flex;
  align-items: center;
  padding: var(--space-xs) var(--space-md);
  border-radius: var(--radius-full);
  font-size: 0.875rem;
  font-weight: 600;
  gap: var(--space-xs);
}

.badge-primary { background: rgba(139, 92, 246, 0.1); color: var(--primary-purple); }
.badge-success { background: rgba(16, 185, 129, 0.1); color: var(--success); }
.badge-warning { background: rgba(245, 158, 11, 0.1); color: var(--warning); }
.badge-error { background: rgba(239, 68, 68, 0.1); color: var(--error); }
.badge-info { background: rgba(59, 130, 246, 0.1); color: var(--info); }

/* Button Component */
.btn {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  gap: var(--space-sm);
  padding: var(--space-md) var(--space-xl);
  border-radius: var(--radius-lg);
  font-weight: 600;
  font-size: 0.9375rem;
  border: none;
  cursor: pointer;
  transition: all var(--transition-fast);
  text-decoration: none;
  font-family: 'Inter', sans-serif;
}

.btn:disabled {
  opacity: 0.5;
  cursor: not-allowed;
}

.btn-primary {
  background: linear-gradient(135deg, var(--primary-purple) 0%, var(--primary-blue) 100%);
  color: white;
}

.btn-primary:hover:not(:disabled) {
  transform: translateY(-2px);
  box-shadow: 0 8px 16px rgba(139, 92, 246, 0.3);
}

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

.btn-success:hover:not(:disabled) {
  background: #059669;
  transform: translateY(-2px);
}

.btn-outline {
  background: transparent;
  border: 2px solid var(--primary-purple);
  color: var(--primary-purple);
}

.btn-outline:hover:not(:disabled) {
  background: var(--primary-purple);
  color: white;
}

.btn-lg {
  padding: var(--space-lg) var(--space-2xl);
  font-size: 1.125rem;
}

.btn-sm {
  padding: var(--space-sm) var(--space-md);
  font-size: 0.875rem;
}

/* Grid System */
.grid {
  display: grid;
  gap: var(--space-xl);
}

.grid-cols-1 { grid-template-columns: repeat(1, 1fr); }
.grid-cols-2 { grid-template-columns: repeat(2, 1fr); }
.grid-cols-3 { grid-template-columns: repeat(3, 1fr); }
.grid-cols-4 { grid-template-columns: repeat(4, 1fr); }

@media (max-width: 1024px) {
  .grid-cols-4 { grid-template-columns: repeat(2, 1fr); }
  .grid-cols-3 { grid-template-columns: repeat(2, 1fr); }
}

@media (max-width: 640px) {
  .grid-cols-4,
  .grid-cols-3,
  .grid-cols-2 {
    grid-template-columns: repeat(1, 1fr);
  }
}

/* Subject Card */
.subject-card {
  background: var(--bg-primary);
  border-radius: var(--radius-xl);
  padding: var(--space-xl);
  border: 2px solid var(--border-color);
  transition: all var(--transition-base);
  cursor: pointer;
  position: relative;
  overflow: hidden;
}

.subject-card::before {
  content: '';
  position: absolute;
  top: 0;
  left: 0;
  right: 0;
  height: 4px;
  background: linear-gradient(90deg, var(--primary-purple), var(--primary-blue));
  transform: scaleX(0);
  transition: transform var(--transition-base);
}

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

.subject-card:hover {
  transform: translateY(-6px);
  box-shadow: var(--shadow-xl);
  border-color: var(--primary-purple);
}

.subject-icon {
  width: 64px;
  height: 64px;
  border-radius: var(--radius-lg);
  display: flex;
  align-items: center;
  justify-content: center;
  font-size: 2rem;
  margin-bottom: var(--space-lg);
  background: linear-gradient(135deg, var(--primary-purple) 0%, var(--primary-blue) 100%);
  color: white;
}

.subject-title {
  font-size: 1.25rem;
  font-weight: 700;
  margin-bottom: var(--space-sm);
  color: var(--text-primary);
}

.subject-description {
  font-size: 0.875rem;
  color: var(--text-secondary);
  margin-bottom: var(--space-lg);
}

/* Progress Bar */
.progress-bar {
  width: 100%;
  height: 8px;
  background: var(--bg-tertiary);
  border-radius: var(--radius-full);
  overflow: hidden;
  margin-bottom: var(--space-sm);
}

.progress-fill {
  height: 100%;
  background: linear-gradient(90deg, var(--primary-purple), var(--primary-blue));
  border-radius: var(--radius-full);
  transition: width var(--transition-slow);
  position: relative;
  overflow: hidden;
}

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

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

/* Stats Widget */
.stat-widget {
  background: var(--bg-primary);
  border-radius: var(--radius-xl);
  padding: var(--space-xl);
  text-align: center;
  border: 1px solid var(--border-color);
  transition: all var(--transition-base);
}

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

.stat-icon {
  width: 56px;
  height: 56px;
  margin: 0 auto var(--space-md);
  border-radius: var(--radius-lg);
  display: flex;
  align-items: center;
  justify-content: center;
  font-size: 1.75rem;
}

.stat-number {
  font-size: 2rem;
  font-weight: 800;
  margin-bottom: var(--space-xs);
  background: linear-gradient(135deg, var(--primary-purple) 0%, var(--primary-blue) 100%);
  -webkit-background-clip: text;
  -webkit-text-fill-color: transparent;
  background-clip: text;
}

.stat-label {
  font-size: 0.875rem;
  color: var(--text-secondary);
  font-weight: 500;
}

/* Container */
.container {
  max-width: 1280px;
  margin: 0 auto;
  padding: 0 var(--space-xl);
}

.container-sm {
  max-width: 768px;
}

.container-lg {
  max-width: 1536px;
}

/* Spacing Utilities */
.mt-1 { margin-top: var(--space-xs); }
.mt-2 { margin-top: var(--space-sm); }
.mt-3 { margin-top: var(--space-md); }
.mt-4 { margin-top: var(--space-lg); }
.mt-5 { margin-top: var(--space-xl); }
.mt-6 { margin-top: var(--space-2xl); }

.mb-1 { margin-bottom: var(--space-xs); }
.mb-2 { margin-bottom: var(--space-sm); }
.mb-3 { margin-bottom: var(--space-md); }
.mb-4 { margin-bottom: var(--space-lg); }
.mb-5 { margin-bottom: var(--space-xl); }
.mb-6 { margin-bottom: var(--space-2xl); }

.p-3 { padding: var(--space-md); }
.p-4 { padding: var(--space-lg); }
.p-5 { padding: var(--space-xl); }
.p-6 { padding: var(--space-2xl); }

/* Text Utilities */
.text-center { text-align: center; }
.text-right { text-align: right; }
.text-left { text-align: left; }

.text-primary { color: var(--text-primary); }
.text-secondary { color: var(--text-secondary); }
.text-tertiary { color: var(--text-tertiary); }

/* Hero Section */
.hero {
  background: linear-gradient(135deg, rgba(139, 92, 246, 0.1) 0%, rgba(59, 130, 246, 0.1) 100%);
  padding: var(--space-2xl) 0;
  border-radius: var(--radius-2xl);
  margin-bottom: var(--space-2xl);
  text-align: center;
  position: relative;
  overflow: hidden;
}

.hero::before {
  content: '';
  position: absolute;
  top: -50%;
  right: -50%;
  width: 100%;
  height: 100%;
  background: radial-gradient(circle, rgba(139, 92, 246, 0.15) 0%, transparent 70%);
  animation: float 6s ease-in-out infinite;
}

@keyframes float {
  0%, 100% { transform: translate(0, 0); }
  50% { transform: translate(-20px, -20px); }
}

.hero-title {
  font-size: clamp(2rem, 5vw, 3.5rem);
  margin-bottom: var(--space-md);
  font-weight: 800;
  background: linear-gradient(135deg, var(--primary-purple) 0%, var(--primary-blue) 100%);
  -webkit-background-clip: text;
  -webkit-text-fill-color: transparent;
  background-clip: text;
}

.hero-subtitle {
  font-size: clamp(1rem, 2vw, 1.25rem);
  color: var(--text-secondary);
  margin-bottom: var(--space-xl);
}

/* Quiz Card */
.quiz-card {
  background: var(--bg-primary);
  border-radius: var(--radius-xl);
  padding: var(--space-2xl);
  box-shadow: var(--shadow-lg);
  border: 2px solid var(--border-color);
  margin-bottom: var(--space-xl);
  animation: slideIn 0.5s ease-out;
}

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

.quiz-question {
  font-size: 1.5rem;
  font-weight: 700;
  margin-bottom: var(--space-xl);
  color: var(--text-primary);
  line-height: 1.4;
}

.quiz-options {
  display: flex;
  flex-direction: column;
  gap: var(--space-md);
}

.quiz-option {
  padding: var(--space-lg);
  background: var(--bg-secondary);
  border: 2px solid var(--border-color);
  border-radius: var(--radius-lg);
  cursor: pointer;
  transition: all var(--transition-fast);
  font-weight: 500;
}

.quiz-option:hover {
  background: var(--bg-tertiary);
  border-color: var(--primary-purple);
  transform: translateX(8px);
}

.quiz-option.correct {
  background: rgba(16, 185, 129, 0.1);
  border-color: var(--success);
  color: var(--success);
}

.quiz-option.incorrect {
  background: rgba(239, 68, 68, 0.1);
  border-color: var(--error);
  color: var(--error);
}

.quiz-option.disabled {
  opacity: 0.6;
  cursor: not-allowed;
}

/* Feedback Section */
.feedback {
  padding: var(--space-lg);
  border-radius: var(--radius-lg);
  margin-top: var(--space-lg);
  animation: fadeIn 0.3s ease-out;
}

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

.feedback.correct {
  background: rgba(16, 185, 129, 0.1);
  border: 2px solid var(--success);
  color: var(--success);
}

.feedback.incorrect {
  background: rgba(239, 68, 68, 0.1);
  border: 2px solid var(--error);
  color: var(--error);
}

/* Loading Spinner */
.spinner {
  width: 40px;
  height: 40px;
  border: 4px solid var(--border-color);
  border-top-color: var(--primary-purple);
  border-radius: 50%;
  animation: spin 1s linear infinite;
}

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

/* Responsive Design */
@media (max-width: 768px) {
  :root {
    --space-xl: 1.5rem;
    --space-2xl: 2rem;
  }
  
  .hero {
    padding: var(--space-xl) var(--space-md);
  }
  
  .quiz-card {
    padding: var(--space-lg);
  }
  
  .quiz-question {
    font-size: 1.25rem;
  }
}