/* CSS Custom Properties - Cool Blue Palette */
:root {
  /* Core Blue Palette */
  --primary-blue: #2563eb;
  --secondary-blue: #3b82f6;
  --light-blue: #60a5fa;
  --pale-blue: #dbeafe;
  --dark-blue: #1e40af;
  --midnight-blue: #1e3a8a;
  
  /* Light Theme */
  --bg-primary: #ffffff;
  --bg-secondary: #f8fafc;
  --bg-tertiary: #f1f5f9;
  --bg-card: #ffffff;
  --bg-elevated: #ffffff;
  --text-primary: #0f172a;
  --text-secondary: #475569;
  --text-tertiary: #64748b;
  --border-primary: #e2e8f0;
  --border-secondary: #cbd5e1;
  --shadow-color: rgba(15, 23, 42, 0.1);
  
  /* Gradients */
  --gradient-primary: linear-gradient(135deg, var(--primary-blue), var(--secondary-blue));
  --gradient-hero: linear-gradient(135deg, #1e3a8a 0%, #3730a3 25%, #4f46e5 50%, #6366f1 75%, #8b5cf6 100%);
  --gradient-card: linear-gradient(145deg, rgba(255,255,255,0.1), rgba(255,255,255,0.05));
  --gradient-glass: linear-gradient(145deg, rgba(255,255,255,0.2), rgba(255,255,255,0.1));
  
  /* Neutral Colors */
  --white: #ffffff;
  --gray-50: #f8fafc;
  --gray-100: #f1f5f9;
  --gray-200: #e2e8f0;
  --gray-300: #cbd5e1;
  --gray-400: #94a3b8;
  --gray-500: #64748b;
  --gray-600: #475569;
  --gray-700: #334155;
  --gray-800: #1e293b;
  --gray-900: #0f172a;
  
  /* Semantic Colors */
  --success: #10b981;
  --warning: #f59e0b;
  --error: #ef4444;
  --success-light: #d1fae5;
  --warning-light: #fef3c7;
  --error-light: #fee2e2;
  
  /* Typography */
  --font-family: 'Inter', 'Segoe UI', Tahoma, Geneva, Verdana, 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-hanzi: 4rem;
  --font-size-hanzi-small: 2rem;
  
  /* Spacing */
  --spacing-xs: 0.25rem;
  --spacing-sm: 0.5rem;
  --spacing-md: 1rem;
  --spacing-lg: 1.5rem;
  --spacing-xl: 2rem;
  --spacing-2xl: 3rem;
  --spacing-3xl: 4rem;
  
  /* Borders */
  --border-radius-sm: 0.375rem;
  --border-radius-md: 0.5rem;
  --border-radius-lg: 0.75rem;
  --border-radius-xl: 1rem;
  --border-radius-2xl: 1.5rem;
  --border-radius-full: 9999px;
  
  /* Shadows */
  --shadow-sm: 0 1px 2px 0 var(--shadow-color);
  --shadow-md: 0 4px 6px -1px var(--shadow-color), 0 2px 4px -1px var(--shadow-color);
  --shadow-lg: 0 10px 15px -3px var(--shadow-color), 0 4px 6px -2px var(--shadow-color);
  --shadow-xl: 0 20px 25px -5px var(--shadow-color), 0 10px 10px -5px var(--shadow-color);
  --shadow-blue: 0 4px 20px rgba(37, 99, 235, 0.3);
  --shadow-glow: 0 0 20px rgba(37, 99, 235, 0.2);
  
  /* 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);
  --transition-bounce: 400ms cubic-bezier(0.68, -0.55, 0.265, 1.55);
  --transition-spring: 300ms cubic-bezier(0.175, 0.885, 0.32, 1.275);
}

/* Dark Theme */
[data-theme="dark"] {
  --bg-primary: #0f172a;
  --bg-secondary: #1e293b;
  --bg-tertiary: #334155;
  --bg-card: #1e293b;
  --bg-elevated: #334155;
  --text-primary: #f8fafc;
  --text-secondary: #cbd5e1;
  --text-tertiary: #94a3b8;
  --border-primary: #334155;
  --border-secondary: #475569;
  --shadow-color: rgba(0, 0, 0, 0.3);
  --gradient-card: linear-gradient(145deg, rgba(0,0,0,0.1), rgba(0,0,0,0.05));
  --gradient-glass: linear-gradient(145deg, rgba(255,255,255,0.1), rgba(255,255,255,0.05));
}

/* High Contrast Mode */
.high-contrast {
  --primary-blue: #0066cc;
  --secondary-blue: #004499;
  --light-blue: #3399ff;
  --pale-blue: #e6f3ff;
  --dark-blue: #003366;
  --border-width: 2px;
  --text-primary: var(--data-theme == "dark" ? #ffffff : #000000);
}

/* Reset and Base Styles */
* {
  margin: 0;
  padding: 0;
  box-sizing: border-box;
}

html {
  font-size: 16px;
  scroll-behavior: smooth;
}

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

/* Focus Styles for Accessibility */
*:focus {
  outline: 2px solid var(--primary-blue);
  outline-offset: 2px;
}

.sr-only {
  position: absolute;
  width: 1px;
  height: 1px;
  padding: 0;
  margin: -1px;
  overflow: hidden;
  clip: rect(0, 0, 0, 0);
  white-space: nowrap;
  border: 0;
}

/* Loading Screen */
.loading-screen {
  position: fixed;
  top: 0;
  left: 0;
  width: 100%;
  height: 100%;
  background: var(--gradient-hero);
  display: flex;
  flex-direction: column;
  align-items: center;
  justify-content: center;
  z-index: 9999;
  transition: opacity var(--transition-slow), visibility var(--transition-slow);
  overflow: hidden;
}

.loading-screen::before {
  content: '';
  position: absolute;
  top: 0;
  left: 0;
  width: 100%;
  height: 100%;
  background: radial-gradient(circle at 30% 70%, rgba(99, 102, 241, 0.3) 0%, transparent 50%),
              radial-gradient(circle at 70% 30%, rgba(139, 92, 246, 0.3) 0%, transparent 50%);
  animation: backgroundPulse 4s ease-in-out infinite;
}

.loading-screen.hidden {
  opacity: 0;
  visibility: hidden;
}

.loader {
  position: relative;
  display: flex;
  flex-direction: column;
  align-items: center;
  justify-content: center;
  z-index: 2;
}

.loader-ring {
  width: 100px;
  height: 100px;
  border: 6px solid rgba(255, 255, 255, 0.2);
  border-top: 6px solid var(--white);
  border-radius: var(--border-radius-full);
  animation: spin 1.2s cubic-bezier(0.4, 0, 0.2, 1) infinite;
  margin-bottom: var(--spacing-lg);
  position: relative;
}

.loader-ring::after {
  content: '';
  position: absolute;
  top: -6px;
  left: -6px;
  right: -6px;
  bottom: -6px;
  border: 2px solid transparent;
  border-top: 2px solid rgba(255, 255, 255, 0.5);
  border-radius: var(--border-radius-full);
  animation: spin 2s linear infinite reverse;
}

.loader-text {
  font-size: var(--font-size-3xl);
  color: var(--white);
  font-weight: 300;
  animation: textPulse 2s ease-in-out infinite;
  margin-bottom: var(--spacing-md);
  text-align: center;
  width: 100%;
  display: flex;
  align-items: center;
  justify-content: center;
  position: relative;
}

.loading-title {
  font-size: var(--font-size-xl);
  color: var(--white);
  font-weight: 600;
  opacity: 0.9;
  animation: fadeInUp 0.8s ease-out 0.5s both;
  text-align: center;
  width: 100%;
}

.loading-subtitle {
  font-size: var(--font-size-base);
  color: var(--white);
  opacity: 0.7;
  animation: fadeInUp 0.8s ease-out 0.8s both;
  text-align: center;
  width: 100%;
}

@keyframes spin {
  0% { transform: rotate(0deg); }
  100% { transform: rotate(360deg); }
}

@keyframes textPulse {
  0%, 100% { 
    opacity: 1; 
    transform: scale(1);
  }
  50% { 
    opacity: 0.8; 
    transform: scale(1.05);
  }
}

@keyframes backgroundPulse {
  0%, 100% { opacity: 0.3; }
  50% { opacity: 0.6; }
}

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

/* Main App Container */
.app {
  min-height: 100vh;
  display: flex;
  flex-direction: column;
  transition: opacity var(--transition-slow);
}

.app.hidden {
  opacity: 0;
}

/* Header */
.header {
  background: var(--bg-card);
  border-bottom: 1px solid var(--border-primary);
  box-shadow: var(--shadow-sm);
  position: sticky;
  top: 0;
  z-index: 100;
  backdrop-filter: blur(12px);
  transition: all var(--transition-base);
}

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

.app-title {
  font-size: var(--font-size-2xl);
  font-weight: 700;
  background: var(--gradient-primary);
  -webkit-background-clip: text;
  -webkit-text-fill-color: transparent;
  background-clip: text;
  position: relative;
}

.app-title::after {
  content: '';
  position: absolute;
  bottom: -2px;
  left: 0;
  width: 100%;
  height: 2px;
  background: var(--gradient-primary);
  transform: scaleX(0);
  transition: transform var(--transition-spring);
  transform-origin: left;
}

.app-title:hover::after {
  transform: scaleX(1);
}

.nav {
  display: flex;
  align-items: center;
  gap: var(--spacing-sm);
}

.nav-btn,
.theme-toggle,
.accessibility-toggle {
  background: var(--bg-secondary);
  border: 1px solid var(--border-primary);
  padding: var(--spacing-sm);
  border-radius: var(--border-radius-lg);
  cursor: pointer;
  transition: all var(--transition-base);
  font-size: var(--font-size-lg);
  color: var(--text-secondary);
  position: relative;
  overflow: hidden;
}

.nav-btn::before,
.theme-toggle::before,
.accessibility-toggle::before {
  content: '';
  position: absolute;
  top: 0;
  left: -100%;
  width: 100%;
  height: 100%;
  background: linear-gradient(90deg, transparent, rgba(255,255,255,0.1), transparent);
  transition: left var(--transition-base);
}

.nav-btn:hover::before,
.theme-toggle:hover::before,
.accessibility-toggle:hover::before {
  left: 100%;
}

.nav-btn:hover,
.theme-toggle:hover,
.accessibility-toggle:hover {
  background: var(--bg-tertiary);
  border-color: var(--primary-blue);
  transform: translateY(-2px);
  box-shadow: var(--shadow-md);
}

.nav-btn.active {
  background: var(--primary-blue);
  color: var(--white);
  border-color: var(--primary-blue);
  box-shadow: var(--shadow-glow);
}

/* Theme Toggle Styles */
.theme-toggle {
  background: var(--bg-card);
  border: 1px solid var(--border-primary);
  border-radius: var(--border-radius-full);
  color: var(--text-primary);
  cursor: pointer;
  display: flex;
  align-items: center;
  justify-content: center;
  min-width: 44px;
  min-height: 44px;
  padding: var(--spacing-sm);
  transition: all var(--transition-fast);
  position: relative;
  overflow: hidden;
}

.theme-toggle:hover {
  background: var(--bg-tertiary);
  border-color: var(--primary-blue);
  transform: scale(1.05);
}

.theme-toggle:active {
  transform: scale(0.95);
}

.theme-toggle svg {
  transition: all var(--transition-base);
}

.theme-toggle .sun-icon,
.theme-toggle .moon-icon {
  position: absolute;
  top: 50%;
  left: 50%;
  transform: translate(-50%, -50%);
}

[data-theme="light"] .theme-toggle .sun-icon {
  opacity: 1;
  transform: translate(-50%, -50%) scale(1);
}

[data-theme="light"] .theme-toggle .moon-icon {
  opacity: 0;
  transform: translate(-50%, -50%) scale(0.5);
  display: none;
}

[data-theme="dark"] .theme-toggle .sun-icon {
  opacity: 0;
  transform: translate(-50%, -50%) scale(0.5);
  display: none;
}

[data-theme="dark"] .theme-toggle .moon-icon {
  opacity: 1;
  transform: translate(-50%, -50%) scale(1);
  display: block;
  fill: #ffffff !important;
  color: #ffffff !important;
}

/* Points Display Styles */
.points-display {
  background: var(--bg-card);
  border: 1px solid var(--border-primary);
  border-radius: var(--border-radius-lg);
  padding: var(--spacing-sm) var(--spacing-md);
  margin-left: var(--spacing-sm);
  display: flex;
  align-items: center;
  justify-content: center;
  min-height: 44px;
  transition: all var(--transition-base);
}

.points-display:hover {
  background: var(--bg-tertiary);
  transform: translateY(-1px);
  box-shadow: var(--shadow-sm);
}

.points-text {
  font-size: var(--font-size-sm);
  font-weight: 600;
  color: var(--text-primary);
  white-space: nowrap;
}

/* Toggle Button Styles */
.toggle-btn {
  background: var(--bg-tertiary);
  border: 2px solid var(--border-primary);
  border-radius: var(--border-radius-full);
  cursor: pointer;
  display: flex;
  align-items: center;
  width: 50px;
  height: 28px;
  padding: 2px;
  position: relative;
  transition: all var(--transition-base);
}

.toggle-btn:hover {
  border-color: var(--primary-blue);
}

.toggle-btn.active {
  background: var(--primary-blue);
  border-color: var(--primary-blue);
}

.toggle-indicator {
  background: var(--white);
  border-radius: 50%;
  width: 20px;
  height: 20px;
  transition: transform var(--transition-base);
  box-shadow: var(--shadow-sm);
}

.toggle-btn.active .toggle-indicator {
  transform: translateX(22px);
}

/* SVG Icon Styles */
.nav-btn svg,
.theme-toggle svg,
.accessibility-toggle svg {
  transition: all var(--transition-base);
  fill: currentColor;
  width: 20px;
  height: 20px;
}

.nav-btn:hover svg,
.theme-toggle:hover svg,
.accessibility-toggle:hover svg {
  transform: scale(1.1);
}

.nav-btn.active svg {
  color: var(--white);
}

/* Enhanced Animations and Transitions */
@keyframes fadeInUp {
  from {
    opacity: 0;
    transform: translateY(20px);
  }
  to {
    opacity: 1;
    transform: translateY(0);
  }
}

@keyframes slideInLeft {
  from {
    opacity: 0;
    transform: translateX(-30px);
  }
  to {
    opacity: 1;
    transform: translateX(0);
  }
}

@keyframes slideInRight {
  from {
    opacity: 0;
    transform: translateX(30px);
  }
  to {
    opacity: 1;
    transform: translateX(0);
  }
}

@keyframes scaleIn {
  from {
    opacity: 0;
    transform: scale(0.9);
  }
  to {
    opacity: 1;
    transform: scale(1);
  }
}

@keyframes bounceIn {
  0% {
    opacity: 0;
    transform: scale(0.3) translateY(-50px);
  }
  50% {
    opacity: 1;
    transform: scale(1.05) translateY(0);
  }
  70% {
    transform: scale(0.95);
  }
  100% {
    transform: scale(1);
  }
}

@keyframes shimmer {
  0% {
    background-position: -200px 0;
  }
  100% {
    background-position: calc(200px + 100%) 0;
  }
}

@keyframes pulseGlow {
  0%, 100% {
    box-shadow: 0 0 5px var(--primary-blue);
  }
  50% {
    box-shadow: 0 0 20px var(--primary-blue), 0 0 30px var(--primary-blue);
  }
}

@keyframes floatUp {
  0%, 100% {
    transform: translateY(0px);
  }
  50% {
    transform: translateY(-10px);
  }
}

/* Smooth page transitions */
.view {
  display: none;
  animation: fadeInUp 0.4s cubic-bezier(0.4, 0, 0.2, 1);
}

.view.active {
  display: block;
}

/* Loading states */
.loading {
  position: relative;
  overflow: hidden;
}

.loading::after {
  content: '';
  position: absolute;
  top: 0;
  left: 0;
  width: 100%;
  height: 100%;
  background: linear-gradient(
    90deg,
    transparent,
    rgba(255, 255, 255, 0.2),
    transparent
  );
  animation: shimmer 1.5s infinite;
}

[data-theme="dark"] .loading::after {
  background: linear-gradient(
    90deg,
    transparent,
    rgba(255, 255, 255, 0.1),
    transparent
  );
}

/* Vocabulary list animations */
.vocab-item {
  animation: slideInLeft 0.3s cubic-bezier(0.4, 0, 0.2, 1);
  animation-fill-mode: both;
}

.vocab-item:nth-child(1) { animation-delay: 0.05s; }
.vocab-item:nth-child(2) { animation-delay: 0.1s; }
.vocab-item:nth-child(3) { animation-delay: 0.15s; }
.vocab-item:nth-child(4) { animation-delay: 0.2s; }
.vocab-item:nth-child(5) { animation-delay: 0.25s; }
.vocab-item:nth-child(n+6) { animation-delay: 0.3s; }

/* Enhanced button interactions */
.btn,
.nav-btn,
.theme-toggle,
.accessibility-toggle {
  transition: all var(--transition-base);
}

.btn:hover,
.nav-btn:hover,
.theme-toggle:hover,
.accessibility-toggle:hover {
  transform: translateY(-2px);
  box-shadow: var(--shadow-lg);
}

.btn:active,
.nav-btn:active,
.theme-toggle:active,
.accessibility-toggle:active {
  transform: translateY(0);
  transition: all 0.1s;
}

/* Card hover effects */
.card {
  transition: all var(--transition-base);
}

.card:hover {
  transform: translateY(-5px);
  box-shadow: var(--shadow-xl);
}

/* Modal animations */
.modal.active {
  animation: scaleIn 0.3s cubic-bezier(0.4, 0, 0.2, 1);
}

.modal-content {
  animation: bounceIn 0.4s cubic-bezier(0.4, 0, 0.2, 1);
}

/* XP gain animation */
.xp-gain {
  animation: floatUp 0.6s ease-out;
  pointer-events: none;
}

/* Streak pulse */
.streak-active {
  animation: pulseGlow 2s infinite;
}

/* Smooth focus transitions */
input:focus,
textarea:focus,
select:focus {
  transform: scale(1.02);
  transition: all var(--transition-base);
}

/* Accessibility improvements */
@media (prefers-reduced-motion: reduce) {
  * {
    animation-duration: 0.01ms !important;
    animation-iteration-count: 1 !important;
    transition-duration: 0.01ms !important;
  }
}

/* Focus indicators */
button:focus-visible,
input:focus-visible,
select:focus-visible {
  outline: 2px solid var(--primary-blue);
  outline-offset: 2px;
}

/* Main Content */
.main-content {
  flex: 1;
  max-width: 1200px;
  margin: 0 auto;
  padding: var(--spacing-lg);
  width: 100%;
}

/* Views */
.view {
  display: none;
  animation: fadeInUp 0.6s cubic-bezier(0.4, 0, 0.2, 1);
}

.view.active {
  display: block;
}

/* Staggered animations for elements */
.progress-card:nth-child(1) { animation-delay: 0.1s; }
.progress-card:nth-child(2) { animation-delay: 0.2s; }
.action-btn:nth-child(1) { animation-delay: 0.1s; }
.action-btn:nth-child(2) { animation-delay: 0.2s; }
.action-btn:nth-child(3) { animation-delay: 0.3s; }
.action-btn:nth-child(4) { animation-delay: 0.4s; }
.reward-card:nth-child(1) { animation-delay: 0.1s; }
.reward-card:nth-child(2) { animation-delay: 0.2s; }
.reward-card:nth-child(3) { animation-delay: 0.3s; }

.stagger-in {
  animation: slideInStagger 0.6s cubic-bezier(0.4, 0, 0.2, 1) both;
}

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

@keyframes slideInStagger {
  from {
    opacity: 0;
    transform: translateY(20px) scale(0.95);
  }
  to {
    opacity: 1;
    transform: translateY(0) scale(1);
  }
}

/* Hero Section */
.hero {
  position: relative;
  background: var(--gradient-hero);
  border-radius: var(--border-radius-xl);
  padding: var(--spacing-3xl) var(--spacing-xl);
  margin-bottom: var(--spacing-2xl);
  overflow: hidden;
  color: var(--white);
  text-align: center;
}

.hero-background {
  position: absolute;
  top: 0;
  left: 0;
  width: 100%;
  height: 100%;
  overflow: hidden;
}

.floating-radicals {
  position: absolute;
  width: 100%;
  height: 100%;
}

.radical {
  position: absolute;
  font-size: var(--font-size-3xl);
  opacity: 0.1;
  animation: float 6s ease-in-out infinite;
  font-weight: 300;
}

.radical:nth-child(1) {
  top: 20%;
  left: 10%;
  animation-delay: 0s;
}

.radical:nth-child(2) {
  top: 60%;
  right: 15%;
  animation-delay: 1.2s;
}

.radical:nth-child(3) {
  top: 30%;
  right: 30%;
  animation-delay: 2.4s;
}

.radical:nth-child(4) {
  bottom: 30%;
  left: 20%;
  animation-delay: 3.6s;
}

.radical:nth-child(5) {
  bottom: 20%;
  right: 10%;
  animation-delay: 4.8s;
}

@keyframes float {
  0%, 100% {
    transform: translateY(0px) rotate(0deg);
  }
  25% {
    transform: translateY(-10px) rotate(5deg);
  }
  50% {
    transform: translateY(-20px) rotate(-5deg);
  }
  75% {
    transform: translateY(-10px) rotate(3deg);
  }
}

.hero-content {
  position: relative;
  z-index: 2;
}

.hero-title {
  font-size: var(--font-size-4xl);
  font-weight: 700;
  margin-bottom: var(--spacing-sm);
}

.hero-subtitle {
  font-size: var(--font-size-lg);
  opacity: 0.9;
}

/* Section Titles */
.section-title {
  font-size: var(--font-size-xl);
  font-weight: 600;
  color: var(--gray-800);
  margin-bottom: var(--spacing-lg);
}

/* Quick Start Section */
.quick-start {
  margin-bottom: var(--spacing-2xl);
}

.quick-actions {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(250px, 1fr));
  gap: var(--spacing-lg);
}

/* Action Buttons */
.action-btn {
  display: flex;
  align-items: center;
  justify-content: center;
  gap: var(--spacing-sm);
  padding: var(--spacing-lg) var(--spacing-xl);
  border: none;
  border-radius: var(--border-radius-lg);
  font-size: var(--font-size-base);
  font-weight: 600;
  cursor: pointer;
  transition: all var(--transition-base);
  position: relative;
  overflow: hidden;
  min-height: 60px;
}

.action-btn.primary {
  background: var(--gradient-primary);
  color: var(--white);
  box-shadow: var(--shadow-blue);
}

.action-btn.secondary {
  background: var(--white);
  color: var(--primary-blue);
  border: 2px solid var(--pale-blue);
  box-shadow: var(--shadow-md);
}

.action-btn.danger {
  background: var(--error);
  color: var(--white);
}

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

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

.btn-icon {
  font-size: var(--font-size-xl);
}

.btn-text {
  flex: 1;
}

.review-count {
  background: var(--error);
  color: var(--white);
  border-radius: var(--border-radius-full);
  padding: var(--spacing-xs) var(--spacing-sm);
  font-size: var(--font-size-xs);
  font-weight: 700;
  min-width: 20px;
  text-align: center;
}

/* Progress Summary */
.progress-cards {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(300px, 1fr));
  gap: var(--spacing-lg);
}

.progress-card {
  background: var(--bg-card);
  border: 1px solid var(--border-primary);
  border-radius: var(--border-radius-xl);
  padding: var(--spacing-xl);
  box-shadow: var(--shadow-md);
  transition: all var(--transition-base);
  position: relative;
  overflow: hidden;
  backdrop-filter: blur(10px);
}

.progress-card::before {
  content: '';
  position: absolute;
  top: 0;
  left: -100%;
  width: 100%;
  height: 100%;
  background: var(--gradient-glass);
  transition: left var(--transition-slow);
}

.progress-card:hover {
  transform: translateY(-8px) scale(1.02);
  box-shadow: var(--shadow-xl);
  border-color: var(--primary-blue);
}

.progress-card:hover::before {
  left: 0;
}

.progress-ring-container {
  position: relative;
  display: flex;
  align-items: center;
  justify-content: center;
  margin-bottom: var(--spacing-lg);
}

.progress-ring {
  transform: rotate(-90deg);
  filter: drop-shadow(0 0 8px rgba(37, 99, 235, 0.3));
}

.progress-ring-bg {
  stroke: var(--border-secondary);
  transition: stroke var(--transition-base);
}

.progress-ring-fill {
  stroke: var(--primary-blue);
  stroke-linecap: round;
  stroke-dasharray: 188.4;
  stroke-dashoffset: 188.4;
  transition: stroke-dashoffset var(--transition-slow), stroke var(--transition-base);
  filter: drop-shadow(0 0 4px rgba(37, 99, 235, 0.5));
}

.progress-percentage {
  position: absolute;
  font-size: var(--font-size-lg);
  font-weight: 700;
  color: var(--primary-blue);
  animation: counterPulse 0.8s ease-out;
}

@keyframes counterPulse {
  0% { 
    transform: scale(0.8);
    opacity: 0;
  }
  50% { 
    transform: scale(1.1);
    opacity: 1;
  }
  100% { 
    transform: scale(1);
    opacity: 1;
  }
}

.progress-info {
  text-align: center;
}

.progress-label {
  display: block;
  font-size: var(--font-size-sm);
  color: var(--text-tertiary);
  margin-bottom: var(--spacing-xs);
  font-weight: 500;
}

.progress-count {
  display: block;
  font-size: var(--font-size-2xl);
  font-weight: 800;
  color: var(--text-primary);
  background: var(--gradient-primary);
  -webkit-background-clip: text;
  -webkit-text-fill-color: transparent;
  background-clip: text;
}

.progress-stats {
  display: grid;
  grid-template-columns: repeat(3, 1fr);
  gap: var(--spacing-lg);
}

.stat-item {
  text-align: center;
}

.stat-value {
  display: block;
  font-size: var(--font-size-2xl);
  font-weight: 700;
  color: var(--primary-blue);
  margin-bottom: var(--spacing-xs);
}

.stat-label {
  font-size: var(--font-size-sm);
  color: var(--gray-600);
}

/* Back Button */
.back-btn {
  background: none;
  border: none;
  font-size: var(--font-size-2xl);
  color: var(--gray-600);
  cursor: pointer;
  padding: var(--spacing-sm);
  border-radius: var(--border-radius-md);
  transition: all var(--transition-fast);
}

.back-btn:hover {
  color: var(--primary-blue);
  background: var(--gray-100);
}

/* Practice View */
.practice-container,
.srs-container,
.lookup-container,
.write-container,
.settings-container {
  max-width: 800px;
  margin: 0 auto;
}

.practice-header,
.srs-header,
.lookup-header,
.write-header,
.settings-header {
  display: flex;
  align-items: center;
  justify-content: space-between;
  margin-bottom: var(--spacing-2xl);
}

.practice-title,
.srs-title,
.lookup-title,
.write-title,
.settings-title {
  font-size: var(--font-size-2xl);
  font-weight: 700;
  color: var(--gray-800);
  flex: 1;
  text-align: center;
}

.practice-controls,
.write-controls {
  display: flex;
  gap: var(--spacing-sm);
}

.toggle-btn,
.clear-btn {
  background: var(--white);
  border: 2px solid var(--gray-200);
  border-radius: var(--border-radius-md);
  padding: var(--spacing-sm);
  cursor: pointer;
  transition: all var(--transition-fast);
  font-size: var(--font-size-lg);
}

.toggle-btn:hover,
.clear-btn:hover {
  border-color: var(--primary-blue);
  color: var(--primary-blue);
}

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

/* Card Container */
.card-container {
  position: relative;
  margin-bottom: var(--spacing-2xl);
  perspective: 1000px;
}

.practice-card {
  background: var(--white);
  border-radius: var(--border-radius-xl);
  box-shadow: var(--shadow-lg);
  padding: var(--spacing-3xl);
  text-align: center;
  transition: transform var(--transition-base);
  transform-style: preserve-3d;
}

.practice-card.flipped {
  transform: rotateY(180deg);
}

.card-front,
.card-back {
  backface-visibility: hidden;
}

.card-back {
  position: absolute;
  top: 0;
  left: 0;
  width: 100%;
  height: 100%;
  transform: rotateY(180deg);
  display: flex;
  flex-direction: column;
  justify-content: center;
  padding: var(--spacing-3xl);
}

.hanzi {
  font-size: var(--font-size-hanzi);
  font-weight: 300;
  color: var(--gray-800);
  margin-bottom: var(--spacing-lg);
  line-height: 1;
}

.hanzi.small {
  font-size: var(--font-size-hanzi-small);
  margin-bottom: var(--spacing-md);
}

.pinyin {
  font-size: var(--font-size-xl);
  color: var(--primary-blue);
  font-weight: 500;
  margin-bottom: var(--spacing-md);
}

.meaning {
  font-size: var(--font-size-lg);
  color: var(--gray-700);
  margin-bottom: var(--spacing-lg);
}

.example {
  font-size: var(--font-size-base);
  color: var(--gray-600);
  font-style: italic;
}

.reveal-btn {
  background: var(--gradient-primary);
  color: var(--white);
  border: none;
  border-radius: var(--border-radius-lg);
  padding: var(--spacing-md) var(--spacing-xl);
  font-size: var(--font-size-base);
  font-weight: 600;
  cursor: pointer;
  transition: all var(--transition-base);
  margin-top: var(--spacing-lg);
}

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

/* Response Buttons */
.response-buttons {
  display: flex;
  gap: var(--spacing-md);
  justify-content: center;
  opacity: 0;
  transform: translateY(20px);
  transition: all var(--transition-base);
}

.response-buttons:not(.hidden) {
  opacity: 1;
  transform: translateY(0);
}

.response-btn {
  flex: 1;
  max-width: 200px;
  background: var(--white);
  border: 2px solid;
  border-radius: var(--border-radius-lg);
  padding: var(--spacing-lg);
  cursor: pointer;
  transition: all var(--transition-base);
  position: relative;
  overflow: hidden;
}

.response-btn.wrong {
  border-color: var(--error);
  color: var(--error);
}

.response-btn.partial {
  border-color: var(--warning);
  color: var(--warning);
}

.response-btn.correct {
  border-color: var(--success);
  color: var(--success);
}

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

.response-btn.wrong:hover {
  background: var(--error-light);
}

.response-btn.partial:hover {
  background: var(--warning-light);
}

.response-btn.correct:hover {
  background: var(--success-light);
}

.response-icon {
  display: block;
  font-size: var(--font-size-xl);
  margin-bottom: var(--spacing-sm);
}

.response-text {
  display: block;
  font-weight: 600;
  margin-bottom: var(--spacing-xs);
}

.keyboard-hint {
  position: absolute;
  top: var(--spacing-sm);
  right: var(--spacing-sm);
  background: var(--gray-200);
  color: var(--gray-600);
  border-radius: var(--border-radius-sm);
  padding: var(--spacing-xs);
  font-size: var(--font-size-xs);
  font-weight: 600;
}

/* SRS Progress Bar */
.progress-bar-container {
  margin-bottom: var(--spacing-xl);
}

.progress-bar {
  width: 100%;
  height: 6px;
  background: var(--gray-200);
  border-radius: var(--border-radius-full);
  overflow: hidden;
}

.progress-bar-fill {
  height: 100%;
  background: var(--gradient-primary);
  border-radius: var(--border-radius-full);
  transition: width var(--transition-base);
  width: 0%;
}

.review-progress {
  font-size: var(--font-size-sm);
  color: var(--gray-600);
}

.srs-complete {
  text-align: center;
  padding: var(--spacing-3xl);
}

.srs-complete h3 {
  font-size: var(--font-size-2xl);
  margin-bottom: var(--spacing-lg);
  color: var(--success);
}

/* Lookup/Notebook View */
.search-container {
  margin-bottom: var(--spacing-2xl);
}

.search-input {
  width: 100%;
  padding: var(--spacing-md) var(--spacing-lg);
  border: 2px solid var(--gray-200);
  border-radius: var(--border-radius-lg);
  font-size: var(--font-size-base);
  transition: all var(--transition-fast);
  margin-bottom: var(--spacing-lg);
}

.search-input:focus {
  border-color: var(--primary-blue);
  box-shadow: 0 0 0 3px rgba(37, 99, 235, 0.1);
}

.filter-tabs {
  display: flex;
  gap: var(--spacing-sm);
  overflow-x: auto;
}

.filter-tab {
  background: var(--white);
  border: 2px solid var(--gray-200);
  border-radius: var(--border-radius-md);
  padding: var(--spacing-sm) var(--spacing-lg);
  cursor: pointer;
  transition: all var(--transition-fast);
  white-space: nowrap;
  font-weight: 500;
}

.filter-tab:hover {
  border-color: var(--primary-blue);
}

.filter-tab.active {
  background: var(--primary-blue);
  color: var(--white);
  border-color: var(--primary-blue);
}

.vocab-list {
  display: grid;
  gap: var(--spacing-md);
}

.vocab-item {
  background: var(--white);
  border-radius: var(--border-radius-lg);
  padding: var(--spacing-lg);
  box-shadow: var(--shadow-sm);
  cursor: pointer;
  transition: all var(--transition-base);
  display: grid;
  grid-template-columns: auto 1fr auto;
  gap: var(--spacing-lg);
  align-items: center;
}

.vocab-item:hover {
  transform: translateY(-2px);
  box-shadow: var(--shadow-md);
}

.vocab-hanzi {
  font-size: var(--font-size-2xl);
  font-weight: 300;
  color: var(--gray-800);
}

.vocab-info {
  flex: 1;
}

.vocab-pinyin {
  font-size: var(--font-size-base);
  color: var(--primary-blue);
  font-weight: 500;
  margin-bottom: var(--spacing-xs);
}

.vocab-meaning {
  font-size: var(--font-size-sm);
  color: var(--gray-600);
}

.vocab-favorite {
  font-size: var(--font-size-lg);
  opacity: 0.3;
  transition: opacity var(--transition-fast);
}

.vocab-item.favorite .vocab-favorite {
  opacity: 1;
}

/* Write Practice View */
.write-content {
  text-align: center;
}

.character-prompt {
  margin-bottom: var(--spacing-2xl);
}

.target-character {
  font-size: var(--font-size-hanzi);
  font-weight: 300;
  color: var(--gray-800);
  margin-bottom: var(--spacing-md);
}

.character-info {
  display: flex;
  justify-content: center;
  gap: var(--spacing-lg);
  flex-wrap: wrap;
}

.target-pinyin {
  font-size: var(--font-size-lg);
  color: var(--primary-blue);
  font-weight: 500;
}

.target-meaning {
  font-size: var(--font-size-lg);
  color: var(--gray-600);
}

.canvas-container {
  position: relative;
  display: inline-block;
  margin-bottom: var(--spacing-xl);
  border: 3px solid var(--gray-200);
  border-radius: var(--border-radius-lg);
  background: var(--white);
}

#write-canvas {
  display: block;
  cursor: crosshair;
}

.guide-canvas {
  position: absolute;
  top: 0;
  left: 0;
  pointer-events: none;
  opacity: 0.3;
}

.write-feedback {
  margin-bottom: var(--spacing-xl);
}

.feedback-message {
  font-size: var(--font-size-lg);
  color: var(--gray-600);
  margin-bottom: var(--spacing-sm);
}

.feedback-score {
  font-size: var(--font-size-2xl);
  font-weight: 700;
}

.write-actions {
  display: flex;
  gap: var(--spacing-md);
  justify-content: center;
}

/* Settings View */
.settings-content {
  max-width: 600px;
  margin: 0 auto;
}

.settings-section {
  background: var(--white);
  border-radius: var(--border-radius-lg);
  padding: var(--spacing-xl);
  margin-bottom: var(--spacing-xl);
  box-shadow: var(--shadow-sm);
}

.settings-section h3 {
  font-size: var(--font-size-lg);
  font-weight: 600;
  color: var(--gray-800);
  margin-bottom: var(--spacing-lg);
}

.setting-item {
  display: flex;
  align-items: center;
  justify-content: space-between;
  margin-bottom: var(--spacing-lg);
  gap: var(--spacing-md);
}

.setting-item:last-child {
  margin-bottom: 0;
}

.setting-item label {
  font-weight: 500;
  color: var(--gray-700);
}

#difficulty-slider {
  flex: 1;
  margin: 0 var(--spacing-md);
}

.setting-value {
  min-width: 3ch;
  text-align: center;
  font-weight: 600;
  color: var(--primary-blue);
}

#schedule-mode {
  padding: var(--spacing-sm) var(--spacing-md);
  border: 2px solid var(--gray-200);
  border-radius: var(--border-radius-md);
  background: var(--white);
  font-size: var(--font-size-base);
}

/* Modal */
.modal {
  position: fixed;
  top: 0;
  left: 0;
  width: 100%;
  height: 100%;
  background: rgba(0, 0, 0, 0.5);
  display: flex;
  align-items: center;
  justify-content: center;
  z-index: 1000;
  opacity: 0;
  visibility: hidden;
  transition: all var(--transition-base);
}

.modal:not(.hidden) {
  opacity: 1;
  visibility: visible;
}

.modal-content {
  background: var(--white);
  border-radius: var(--border-radius-xl);
  max-width: 500px;
  width: 90%;
  max-height: 80vh;
  overflow-y: auto;
  transform: scale(0.9);
  transition: transform var(--transition-bounce);
}

.modal:not(.hidden) .modal-content {
  transform: scale(1);
}

.modal-header {
  display: flex;
  align-items: center;
  justify-content: space-between;
  padding: var(--spacing-xl) var(--spacing-xl) 0;
}

.modal-close {
  background: none;
  border: none;
  font-size: var(--font-size-2xl);
  color: var(--gray-400);
  cursor: pointer;
  padding: var(--spacing-sm);
  line-height: 1;
}

.modal-close:hover {
  color: var(--gray-600);
}

.modal-body {
  padding: var(--spacing-xl);
}

.character-display {
  display: flex;
  align-items: center;
  gap: var(--spacing-lg);
  margin-bottom: var(--spacing-lg);
}

.modal-hanzi {
  font-size: var(--font-size-hanzi-small);
  font-weight: 300;
  color: var(--gray-800);
}

.modal-info {
  flex: 1;
}

.modal-pinyin {
  font-size: var(--font-size-lg);
  color: var(--primary-blue);
  font-weight: 500;
  margin-bottom: var(--spacing-sm);
}

.modal-meaning {
  font-size: var(--font-size-base);
  color: var(--gray-700);
}

.modal-example {
  background: var(--gray-50);
  border-radius: var(--border-radius-md);
  padding: var(--spacing-md);
  margin-bottom: var(--spacing-lg);
  font-style: italic;
  color: var(--gray-600);
}

.modal-notes {
  margin-bottom: var(--spacing-lg);
}

.modal-notes label {
  display: block;
  font-weight: 500;
  color: var(--gray-700);
  margin-bottom: var(--spacing-sm);
}

#user-notes {
  width: 100%;
  padding: var(--spacing-md);
  border: 2px solid var(--gray-200);
  border-radius: var(--border-radius-md);
  font-family: inherit;
  font-size: var(--font-size-base);
  resize: vertical;
  min-height: 80px;
}

#user-notes:focus {
  border-color: var(--primary-blue);
  outline: none;
}

.modal-actions {
  display: flex;
  align-items: center;
  justify-content: space-between;
}

.favorite-btn {
  background: none;
  border: none;
  font-size: var(--font-size-xl);
  cursor: pointer;
  padding: var(--spacing-sm);
  border-radius: var(--border-radius-md);
  transition: all var(--transition-fast);
}

.favorite-btn:hover {
  background: var(--gray-100);
}

.favorite-btn.active .favorite-icon {
  filter: hue-rotate(45deg) saturate(2) brightness(1.2);
}

/* Success Overlay */
.success-overlay {
  position: fixed;
  top: 0;
  left: 0;
  width: 100%;
  height: 100%;
  background: rgba(16, 185, 129, 0.1);
  display: flex;
  align-items: center;
  justify-content: center;
  z-index: 2000;
  opacity: 0;
  visibility: hidden;
  transition: all var(--transition-base);
}

.success-overlay:not(.hidden) {
  opacity: 1;
  visibility: visible;
}

.success-animation {
  animation: successPop 0.6s ease-out;
}

.success-circle {
  width: 120px;
  height: 120px;
  background: var(--success);
  border-radius: var(--border-radius-full);
  display: flex;
  align-items: center;
  justify-content: center;
  box-shadow: var(--shadow-xl);
}

.success-checkmark {
  font-size: var(--font-size-4xl);
  color: var(--white);
  font-weight: 700;
}

@keyframes successPop {
  0% {
    transform: scale(0) rotate(-180deg);
    opacity: 0;
  }
  50% {
    transform: scale(1.2) rotate(-90deg);
    opacity: 1;
  }
  100% {
    transform: scale(1) rotate(0deg);
    opacity: 1;
  }
}

/* Stroke Order Overlay */
.stroke-order-overlay {
  position: absolute;
  top: 50%;
  left: 50%;
  transform: translate(-50%, -50%);
  background: rgba(255, 255, 255, 0.95);
  border-radius: var(--border-radius-lg);
  padding: var(--spacing-lg);
  box-shadow: var(--shadow-xl);
  opacity: 0;
  visibility: hidden;
  transition: all var(--transition-base);
}

.stroke-order-overlay:not(.hidden) {
  opacity: 1;
  visibility: visible;
}

#stroke-canvas {
  border: 2px solid var(--gray-200);
  border-radius: var(--border-radius-md);
}

/* Points and Rewards Styling */
.points-value {
  color: var(--warning) !important;
  font-weight: 700;
  position: relative;
}

.points-value::after {
  content: '✨';
  position: absolute;
  top: -5px;
  right: -15px;
  font-size: 0.8em;
  animation: sparkle 2s ease-in-out infinite;
}

.points-badge {
  position: absolute;
  top: -8px;
  right: -8px;
  background: linear-gradient(135deg, var(--warning), #ff8c00);
  color: var(--white);
  border-radius: var(--border-radius-full);
  padding: var(--spacing-xs);
  font-size: var(--font-size-xs);
  font-weight: 700;
  min-width: 20px;
  height: 20px;
  display: flex;
  align-items: center;
  justify-content: center;
  line-height: 1;
  box-shadow: 0 2px 8px rgba(245, 158, 11, 0.4);
  animation: pointsBadgePulse 2s ease-in-out infinite;
  border: 2px solid var(--bg-card);
}

.nav-btn {
  position: relative;
}

.points-display {
  display: flex;
  align-items: center;
  gap: var(--spacing-sm);
  background: var(--gradient-primary);
  color: var(--white);
  padding: var(--spacing-sm) var(--spacing-md);
  border-radius: var(--border-radius-full);
  font-weight: 600;
  font-size: var(--font-size-sm);
  box-shadow: var(--shadow-glow);
  position: relative;
  overflow: hidden;
}

.points-display::before {
  content: '';
  position: absolute;
  top: 0;
  left: -100%;
  width: 100%;
  height: 100%;
  background: linear-gradient(90deg, transparent, rgba(255,255,255,0.2), transparent);
  animation: shimmer 3s ease-in-out infinite;
}

.points-display-large {
  display: flex;
  align-items: center;
  gap: var(--spacing-sm);
  background: var(--gradient-primary);
  color: var(--white);
  padding: var(--spacing-md) var(--spacing-lg);
  border-radius: var(--border-radius-xl);
  font-weight: 700;
  font-size: var(--font-size-lg);
  box-shadow: var(--shadow-glow);
  position: relative;
  overflow: hidden;
}

.points-display-large::before {
  content: '';
  position: absolute;
  top: 0;
  left: -100%;
  width: 100%;
  height: 100%;
  background: linear-gradient(90deg, transparent, rgba(255,255,255,0.2), transparent);
  animation: shimmer 3s ease-in-out infinite 1s;
}

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

/* XP Gain Animation */
.xp-gain {
  position: fixed;
  top: 50%;
  left: 50%;
  transform: translate(-50%, -50%);
  background: linear-gradient(135deg, var(--primary-blue), var(--secondary-blue));
  color: var(--white);
  padding: var(--spacing-lg) var(--spacing-xl);
  border-radius: var(--border-radius-2xl);
  font-weight: 800;
  font-size: var(--font-size-2xl);
  z-index: 2001;
  box-shadow: 0 20px 40px rgba(37, 99, 235, 0.3);
  animation: xpPop 2.5s cubic-bezier(0.68, -0.55, 0.265, 1.55) forwards;
  pointer-events: none;
  border: 2px solid rgba(255, 255, 255, 0.2);
  position: relative;
  overflow: hidden;
}

.xp-gain::before {
  content: '';
  position: absolute;
  top: 0;
  left: -100%;
  width: 100%;
  height: 100%;
  background: linear-gradient(90deg, transparent, rgba(255,255,255,0.3), transparent);
  animation: xpShimmer 1s ease-out 0.5s;
}

.xp-gain::after {
  content: '✨';
  position: absolute;
  top: -10px;
  right: -10px;
  font-size: 1.5em;
  animation: xpSparkle 2s ease-out;
}

/* Enhanced Animations */
@keyframes pointsBadgePulse {
  0%, 100% { 
    transform: scale(1);
    box-shadow: 0 2px 8px rgba(245, 158, 11, 0.4);
  }
  50% { 
    transform: scale(1.1);
    box-shadow: 0 4px 16px rgba(245, 158, 11, 0.6);
  }
}

@keyframes sparkle {
  0%, 100% { 
    opacity: 0.6;
    transform: rotate(0deg) scale(1);
  }
  25% { 
    opacity: 1;
    transform: rotate(90deg) scale(1.2);
  }
  50% { 
    opacity: 0.8;
    transform: rotate(180deg) scale(0.9);
  }
  75% { 
    opacity: 1;
    transform: rotate(270deg) scale(1.1);
  }
}

@keyframes shimmer {
  0% { left: -100%; }
  100% { left: 100%; }
}

@keyframes xpPop {
  0% {
    opacity: 0;
    transform: translate(-50%, -50%) scale(0.3) rotate(-180deg);
  }
  15% {
    opacity: 1;
    transform: translate(-50%, -50%) scale(1.2) rotate(-90deg);
  }
  30% {
    transform: translate(-50%, -50%) scale(0.95) rotate(0deg);
  }
  45% {
    transform: translate(-50%, -50%) scale(1.05) rotate(10deg) translateY(-10px);
  }
  60% {
    transform: translate(-50%, -50%) scale(1) rotate(-5deg) translateY(-20px);
  }
  80% {
    opacity: 1;
    transform: translate(-50%, -50%) scale(1) rotate(0deg) translateY(-30px);
  }
  100% {
    opacity: 0;
    transform: translate(-50%, -50%) scale(0.8) rotate(0deg) translateY(-80px);
  }
}

@keyframes xpShimmer {
  0% { left: -100%; }
  100% { left: 100%; }
}

@keyframes xpSparkle {
  0% { 
    opacity: 0;
    transform: rotate(0deg) scale(0);
  }
  20% { 
    opacity: 1;
    transform: rotate(180deg) scale(1.5);
  }
  40% { 
    opacity: 0.8;
    transform: rotate(360deg) scale(1);
  }
  60% { 
    opacity: 1;
    transform: rotate(540deg) scale(1.2);
  }
  100% { 
    opacity: 0;
    transform: rotate(720deg) scale(0);
  }
}

/* Rewards Section */
.rewards-section {
  margin-bottom: var(--spacing-2xl);
  opacity: 0;
  animation: fadeInUp 0.8s ease-out 0.3s both;
}

.rewards-grid {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(300px, 1fr));
  gap: var(--spacing-lg);
}

.rewards-grid-large {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(340px, 1fr));
  gap: var(--spacing-lg);
}

.reward-card {
  background: var(--bg-card);
  border: 2px solid var(--border-primary);
  border-radius: var(--border-radius-xl);
  padding: var(--spacing-lg);
  box-shadow: var(--shadow-md);
  transition: all var(--transition-spring);
  position: relative;
  overflow: hidden;
  backdrop-filter: blur(8px);
}

.reward-card::before {
  content: '';
  position: absolute;
  top: 0;
  left: 0;
  width: 100%;
  height: 100%;
  background: var(--gradient-glass);
  opacity: 0;
  transition: opacity var(--transition-base);
}

.reward-card:hover {
  transform: translateY(-8px) scale(1.03);
  box-shadow: var(--shadow-xl);
}

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

.reward-card.affordable {
  border-color: var(--success);
  box-shadow: 0 4px 20px rgba(16, 185, 129, 0.2);
}

.reward-card.affordable:hover {
  box-shadow: 0 12px 32px rgba(16, 185, 129, 0.3);
  border-color: var(--success);
}

.reward-card.expensive {
  opacity: 0.7;
  border-color: var(--error);
}

.reward-card.expensive:hover {
  opacity: 0.8;
  transform: translateY(-4px) scale(1.01);
}

.reward-header {
  display: flex;
  align-items: center;
  gap: var(--spacing-md);
  margin-bottom: var(--spacing-md);
  position: relative;
  z-index: 2;
}

.reward-icon {
  font-size: var(--font-size-2xl);
  width: 60px;
  height: 60px;
  display: flex;
  align-items: center;
  justify-content: center;
  background: var(--gradient-primary);
  border-radius: var(--border-radius-lg);
  box-shadow: var(--shadow-md);
  position: relative;
  overflow: hidden;
}

.reward-icon::before {
  content: '';
  position: absolute;
  top: -50%;
  left: -50%;
  width: 200%;
  height: 200%;
  background: conic-gradient(transparent, rgba(255,255,255,0.3), transparent);
  animation: iconRotate 3s linear infinite;
}

@keyframes iconRotate {
  from { transform: rotate(0deg); }
  to { transform: rotate(360deg); }
}

.reward-info {
  flex: 1;
}

.reward-name {
  font-size: var(--font-size-lg);
  font-weight: 700;
  color: var(--text-primary);
  margin-bottom: var(--spacing-xs);
}

.reward-cost {
  font-size: var(--font-size-sm);
  color: var(--warning);
  font-weight: 700;
  background: linear-gradient(135deg, var(--warning), #ff8c00);
  -webkit-background-clip: text;
  -webkit-text-fill-color: transparent;
  background-clip: text;
}

.reward-description {
  font-size: var(--font-size-sm);
  color: var(--gray-600);
  margin-bottom: var(--spacing-md);
  line-height: 1.4;
}

.reward-actions {
  display: flex;
  justify-content: space-between;
  align-items: center;
}

.redeem-btn {
  background: var(--gradient-primary);
  color: var(--white);
  border: none;
  border-radius: var(--border-radius-md);
  padding: var(--spacing-sm) var(--spacing-lg);
  font-size: var(--font-size-sm);
  font-weight: 600;
  cursor: pointer;
  transition: all var(--transition-fast);
}

.redeem-btn:hover:not(:disabled) {
  transform: translateY(-1px);
  box-shadow: var(--shadow-blue);
}

.redeem-btn:disabled {
  background: var(--gray-400);
  cursor: not-allowed;
  transform: none;
  box-shadow: none;
}

.reward-status {
  font-size: var(--font-size-xs);
  padding: var(--spacing-xs) var(--spacing-sm);
  border-radius: var(--border-radius-sm);
  font-weight: 600;
  text-transform: uppercase;
  letter-spacing: 0.5px;
}

.reward-status.affordable {
  background: var(--success-light);
  color: var(--success);
}

.reward-status.expensive {
  background: var(--error-light);
  color: var(--error);
}

/* Active Boosts */
.active-boosts {
  background: var(--white);
  border-radius: var(--border-radius-lg);
  padding: var(--spacing-xl);
  margin-bottom: var(--spacing-2xl);
  box-shadow: var(--shadow-md);
}

.boosts-title,
.shop-title {
  font-size: var(--font-size-lg);
  font-weight: 600;
  color: var(--gray-800);
  margin-bottom: var(--spacing-lg);
}

.boosts-list {
  display: grid;
  gap: var(--spacing-md);
}

.boost-item {
  display: flex;
  align-items: center;
  gap: var(--spacing-md);
  background: var(--gradient-primary);
  color: var(--white);
  padding: var(--spacing-md);
  border-radius: var(--border-radius-md);
  box-shadow: var(--shadow-sm);
}

.boost-icon {
  font-size: var(--font-size-xl);
  width: 40px;
  height: 40px;
  display: flex;
  align-items: center;
  justify-content: center;
  background: rgba(255, 255, 255, 0.2);
  border-radius: var(--border-radius-sm);
}

.boost-details {
  flex: 1;
}

.boost-name {
  font-weight: 600;
  margin-bottom: var(--spacing-xs);
}

.boost-duration {
  font-size: var(--font-size-sm);
  opacity: 0.9;
}

.boost-timer {
  font-size: var(--font-size-sm);
  font-weight: 600;
  background: rgba(255, 255, 255, 0.2);
  padding: var(--spacing-xs) var(--spacing-sm);
  border-radius: var(--border-radius-sm);
}

.no-boosts {
  text-align: center;
  color: var(--gray-500);
  font-style: italic;
  padding: var(--spacing-lg);
}

/* Reward Modal */
.reward-preview {
  display: flex;
  align-items: center;
  gap: var(--spacing-lg);
  margin-bottom: var(--spacing-lg);
  padding: var(--spacing-lg);
  background: var(--gray-50);
  border-radius: var(--border-radius-md);
}

.reward-icon-large {
  font-size: var(--font-size-4xl);
  width: 80px;
  height: 80px;
  display: flex;
  align-items: center;
  justify-content: center;
  background: var(--pale-blue);
  border-radius: var(--border-radius-lg);
}

.reward-details h4 {
  font-size: var(--font-size-lg);
  font-weight: 600;
  color: var(--gray-800);
  margin-bottom: var(--spacing-sm);
}

.reward-details p {
  color: var(--gray-600);
  margin-bottom: var(--spacing-md);
}

.reward-cost .cost-label {
  color: var(--gray-600);
}

.reward-cost .cost-value {
  color: var(--warning);
  font-weight: 700;
}

.points-check {
  background: var(--white);
  border: 2px solid var(--gray-200);
  border-radius: var(--border-radius-md);
  padding: var(--spacing-md);
  margin-bottom: var(--spacing-lg);
}

.current-points,
.points-after {
  display: flex;
  justify-content: space-between;
  margin-bottom: var(--spacing-sm);
  font-weight: 500;
}

.points-after {
  margin-bottom: 0;
  color: var(--primary-blue);
  font-weight: 600;
}

.points-after.insufficient {
  color: var(--error);
}

/* XP Gain Animation */
.xp-gain {
  position: fixed;
  top: 50%;
  left: 50%;
  transform: translate(-50%, -50%);
  background: var(--gradient-primary);
  color: var(--white);
  padding: var(--spacing-md) var(--spacing-lg);
  border-radius: var(--border-radius-lg);
  font-weight: 700;
  font-size: var(--font-size-lg);
  z-index: 2001;
  box-shadow: var(--shadow-xl);
  animation: xpPop 2s ease-out forwards;
  pointer-events: none;
}

@keyframes xpPop {
  0% {
    opacity: 0;
    transform: translate(-50%, -50%) scale(0.3);
  }
  20% {
    opacity: 1;
    transform: translate(-50%, -50%) scale(1.1);
  }
  40% {
    transform: translate(-50%, -50%) scale(1) translateY(-20px);
  }
  100% {
    opacity: 0;
    transform: translate(-50%, -50%) scale(1) translateY(-60px);
  }
}

/* Responsive Design Updates */
@media (max-width: 768px) {
  /* Header improvements */
  .header {
    padding: var(--spacing-sm) 0;
  }
  
  .header-content {
    padding: 0 var(--spacing-md);
    gap: var(--spacing-sm);
  }
  
  .app-title {
    font-size: var(--font-size-lg);
  }
  
  .nav {
    gap: var(--spacing-xs);
  }
  
  .nav-btn,
  .theme-toggle {
    min-width: 40px;
    min-height: 40px;
    padding: var(--spacing-xs);
  }
  
  .points-display {
    padding: var(--spacing-xs) var(--spacing-sm);
    margin-left: var(--spacing-xs);
  }
  
  .points-text {
    font-size: var(--font-size-xs);
  }
  
  .main-content {
    padding: var(--spacing-md);
  }
  
  .hero {
    padding: var(--spacing-2xl) var(--spacing-lg);
    margin-bottom: var(--spacing-xl);
  }
  
  .hero-title {
    font-size: var(--font-size-3xl);
  }

  /* Card improvements */
  .card {
    margin: var(--spacing-sm);
    padding: var(--spacing-md);
  }
  
  .practice-card {
    margin: var(--spacing-sm) 0;
    padding: var(--spacing-lg);
  }
  
  .hanzi {
    font-size: 3rem;
  }

  /* Button improvements */
  .btn,
  .response-btn {
    min-height: 44px; /* Minimum touch target */
    padding: var(--spacing-sm) var(--spacing-md);
    font-size: var(--font-size-base);
  }
  
  .response-buttons {
    gap: var(--spacing-sm);
    flex-direction: column;
  }
  
  .response-btn {
    width: 100%;
    justify-content: center;
  }

  /* Hide keyboard hints on mobile */
  .keyboard-hint {
    display: none;
  }
  
  /* Prevent zoom on input focus */
  input[type="text"],
  input[type="search"],
  textarea,
  select {
    font-size: 16px; /* Prevents iOS zoom */
  }
  
  .quick-actions {
    grid-template-columns: 1fr;
  }
  
  .progress-cards {
    grid-template-columns: 1fr;
  }
  
  .progress-stats {
    grid-template-columns: 1fr;
    gap: var(--spacing-md);
  }
  
  .rewards-grid,
  .rewards-grid-large {
    grid-template-columns: 1fr;
  }
  
  .section-header {
    flex-direction: column;
    gap: var(--spacing-md);
    text-align: center;
  }
  
  .points-display {
    order: -1;
  }
  
  .practice-header,
  .srs-header,
  .lookup-header,
  .write-header,
  .settings-header,
  .rewards-header {
    flex-direction: column;
    gap: var(--spacing-md);
    text-align: center;
  }
  
  .practice-title,
  .srs-title,
  .lookup-title,
  .write-title,
  .settings-title,
  .rewards-title {
    order: 1;
  }
  
  .back-btn {
    align-self: flex-start;
    order: 0;
  }
  
  .practice-controls,
  .write-controls,
  .points-display-large {
    order: 2;
  }
  
  .hanzi {
    font-size: calc(var(--font-size-hanzi) * 0.8);
  }
  
  .response-buttons {
    flex-direction: column;
  }
  
  .character-info {
    flex-direction: column;
    gap: var(--spacing-sm);
  }
  
  .canvas-container {
    width: 280px;
    height: 280px;
  }
  
  #write-canvas,
  .guide-canvas {
    width: 280px;
    height: 280px;
  }
  
  .filter-tabs {
    justify-content: center;
  }
  
  .vocab-item {
    grid-template-columns: auto 1fr;
    grid-template-rows: auto auto;
  }
  
  .vocab-favorite {
    grid-column: 2;
    grid-row: 1;
    justify-self: end;
  }
  
  .vocab-info {
    grid-column: 1 / -1;
    grid-row: 2;
  }
  
  .reward-preview {
    flex-direction: column;
    text-align: center;
  }
  
  .reward-header {
    flex-direction: column;
    text-align: center;
  }
  
  .boost-item {
    flex-direction: column;
    text-align: center;
    gap: var(--spacing-sm);
  }
}

@media (max-width: 480px) {
  .header-content {
    padding: var(--spacing-sm) var(--spacing-md);
  }
  
  .app-title {
    font-size: var(--font-size-xl);
  }
  
  .main-content {
    padding: var(--spacing-sm);
  }
  
  .practice-card {
    padding: var(--spacing-xl);
  }
  
  .modal-content {
    margin: var(--spacing-md);
    width: calc(100% - var(--spacing-xl));
  }
  
  .character-display {
    flex-direction: column;
    text-align: center;
  }
  
  .write-actions {
    flex-direction: column;
  }
  
  .setting-item {
    flex-direction: column;
    align-items: stretch;
    gap: var(--spacing-sm);
  }
}

/* Utility Classes */
.hidden {
  display: none !important;
}

.visually-hidden {
  position: absolute !important;
  width: 1px !important;
  height: 1px !important;
  padding: 0 !important;
  margin: -1px !important;
  overflow: hidden !important;
  clip: rect(0, 0, 0, 0) !important;
  white-space: nowrap !important;
  border: 0 !important;
}

/* Animation Classes */
.fade-in {
  animation: fadeIn var(--transition-base) ease-out;
}

.slide-up {
  animation: slideUp var(--transition-base) ease-out;
}

.bounce-in {
  animation: bounceIn var(--transition-bounce) ease-out;
}

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

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

@keyframes bounceIn {
  0% {
    opacity: 0;
    transform: scale(0.3);
  }
  50% {
    opacity: 1;
    transform: scale(1.05);
  }
  70% {
    transform: scale(0.9);
  }
  100% {
    opacity: 1;
    transform: scale(1);
  }
}

/* Print Styles */
@media print {
  .header,
  .nav,
  .back-btn,
  .action-btn,
  .response-buttons {
    display: none !important;
  }
  
  .main-content {
    padding: 0;
  }
  
  .practice-card {
    box-shadow: none;
    border: 1px solid var(--gray-300);
  }
}

/* Practice Canvas Styles */
.practice-canvas-container {
  background: var(--bg-card);
  border: 1px solid var(--border-primary);
  border-radius: var(--border-radius-lg);
  padding: var(--spacing-lg);
  margin: var(--spacing-lg) 0;
  animation: fadeInUp 0.3s ease-out;
}

.practice-canvas-container.hidden {
  display: none;
}

.canvas-header {
  display: flex;
  justify-content: space-between;
  align-items: center;
  margin-bottom: var(--spacing-md);
  flex-wrap: wrap;
  gap: var(--spacing-sm);
}

.canvas-header h4 {
  font-size: var(--font-size-lg);
  color: var(--text-primary);
  margin: 0;
}

.canvas-controls {
  display: flex;
  gap: var(--spacing-sm);
}

.canvas-btn {
  background: var(--bg-secondary);
  border: 1px solid var(--border-primary);
  border-radius: var(--border-radius-md);
  color: var(--text-primary);
  cursor: pointer;
  font-size: var(--font-size-sm);
  padding: var(--spacing-sm) var(--spacing-md);
  transition: all var(--transition-base);
  min-height: 36px;
  min-width: 60px;
}

.canvas-btn:hover {
  background: var(--bg-tertiary);
  border-color: var(--primary-blue);
  transform: translateY(-1px);
}

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

.canvas-area {
  position: relative;
  display: flex;
  justify-content: center;
  background: var(--white);
  border: 2px solid var(--border-primary);
  border-radius: var(--border-radius-md);
  overflow: hidden;
  max-width: 100%;
}

.canvas-area canvas {
  display: block;
  cursor: crosshair;
  max-width: 100%;
  height: auto;
  touch-action: none; /* Prevent scrolling while drawing */
}

#practice-canvas {
  position: relative;
  z-index: 2;
  background: transparent;
}

#practice-guide-canvas {
  position: absolute;
  top: 0;
  left: 50%;
  transform: translateX(-50%);
  z-index: 1;
  opacity: 0.3;
  pointer-events: none;
}

.practice-btn {
  background: var(--bg-secondary);
  border: 1px solid var(--border-primary);
  border-radius: var(--border-radius-md);
  color: var(--text-primary);
  cursor: pointer;
  font-size: var(--font-size-sm);
  padding: var(--spacing-sm) var(--spacing-md);
  transition: all var(--transition-base);
  margin-top: var(--spacing-md);
  min-height: 40px;
}

.practice-btn:hover {
  background: var(--bg-tertiary);
  border-color: var(--primary-blue);
  transform: translateY(-1px);
}

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

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

/* Mobile Canvas Optimizations */
@media (max-width: 768px) {
  .canvas-area {
    max-width: 100%;
    margin: 0 auto;
  }
  
  .canvas-area canvas {
    width: 100%;
    max-width: 280px;
    height: auto;
  }
  
  .canvas-header {
    flex-direction: column;
    align-items: stretch;
    text-align: center;
  }
  
  .canvas-controls {
    justify-content: center;
  }
  
  .practice-canvas-container {
    padding: var(--spacing-md);
  }
}