/* ==========================================
   PREMIUM NEUMORPHISM UI DESIGN
   Fully Responsive: Mobile | Tablet | Desktop | 4K
   ========================================== */

:root {
  /* Light Theme Colors */
  --bg-light: #e6eaf0;
  --bg-light-elevated: #f0f4f8;
  --text-light: #2c3e50;
  --text-light-secondary: #5a6c7d;
  --shadow-light-1: rgba(163, 177, 198, 0.7);
  --shadow-light-2: rgba(255, 255, 255, 0.9);
  --shadow-inset-1: rgba(163, 177, 198, 0.4);
  --shadow-inset-2: rgba(255, 255, 255, 0.7);
  
  /* Color Palette */
  --primary: #667eea;
  --primary-dark: #5568d3;
  --primary-light: #8b9ef5;
  --secondary: #764ba2;
  --accent: #f093fb;
  --success: #4caf50;
  --success-dark: #45a049;
  --danger: #f44336;
  --danger-dark: #d32f2f;
  --warning: #ff9800;
  --warning-dark: #f57c00;
  --info: #2196f3;
  --info-dark: #1976d2;
  
  /* Spacing System */
  --spacing-xs: 0.25rem;
  --spacing-sm: 0.5rem;
  --spacing-md: 1rem;
  --spacing-lg: 1.5rem;
  --spacing-xl: 2rem;
  --spacing-2xl: 3rem;
  --spacing-3xl: 4rem;
  
  /* Border Radius */
  --radius-sm: 8px;
  --radius-md: 12px;
  --radius-lg: 16px;
  --radius-xl: 20px;
  --radius-2xl: 24px;
  --radius-full: 50%;
  
  /* Typography */
  --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-5xl: 3rem;
  
  /* Transitions */
  --transition-fast: 0.15s ease-in-out;
  --transition-base: 0.3s ease-in-out;
  --transition-slow: 0.5s ease-in-out;
}

/* Dark Theme */
body.dark {
  --bg-light: #1a1d29;
  --bg-light-elevated: #22252f;
  --text-light: #e4e7ec;
  --text-light-secondary: #9ca3af;
  --shadow-light-1: rgba(0, 0, 0, 0.5);
  --shadow-light-2: rgba(255, 255, 255, 0.03);
  --shadow-inset-1: rgba(0, 0, 0, 0.3);
  --shadow-inset-2: rgba(255, 255, 255, 0.02);
  --primary: #7c3aed;
  --primary-dark: #6d28d9;
  --primary-light: #8b5cf6;
}

/* ==========================================
   RESET & BASE STYLES
   ========================================== */

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

html {
  font-size: 16px;
  scroll-behavior: smooth;
  -webkit-font-smoothing: antialiased;
  -moz-osx-font-smoothing: grayscale;
}

body {
  background: var(--bg-light);
  color: var(--text-light);
  font-family: -apple-system, BlinkMacSystemFont, 'Segoe UI', 'Roboto', 'Oxygen',
    'Ubuntu', 'Cantarell', 'Fira Sans', 'Droid Sans', 'Helvetica Neue', sans-serif;
  line-height: 1.6;
  min-height: 100vh;
  padding: var(--spacing-lg);
  transition: background var(--transition-base), color var(--transition-base);
  overflow-x: hidden;
}

::selection {
  background: var(--primary);
  color: white;
}

/* ==========================================
   CONTAINER & LAYOUT
   ========================================== */

.container {
  max-width: 1200px;
  margin: 0 auto;
  width: 100%;
  animation: fadeInUp 0.6s ease-out;
}

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

/* ==========================================
   HEADER SECTION
   ========================================== */

.app-header {
  text-align: center;
  margin-bottom: var(--spacing-2xl);
  padding: var(--spacing-2xl) var(--spacing-md);
  position: relative;
}

.app-header h1 {
  font-size: clamp(var(--font-size-3xl), 5vw, var(--font-size-5xl));
  font-weight: 800;
  margin-bottom: var(--spacing-md);
  background: linear-gradient(135deg, var(--primary), var(--secondary), var(--accent));
  -webkit-background-clip: text;
  -webkit-text-fill-color: transparent;
  background-clip: text;
  letter-spacing: -0.02em;
  animation: gradientShift 8s ease infinite;
  background-size: 200% 200%;
}

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

.tagline {
  font-size: var(--font-size-lg);
  color: var(--text-light-secondary);
  font-weight: 500;
  letter-spacing: 0.02em;
}

/* ==========================================
   NEUMORPHIC CARD COMPONENT
   ========================================== */

.neumo-card {
  background: var(--bg-light);
  border-radius: var(--radius-xl);
  padding: var(--spacing-xl);
  margin-bottom: var(--spacing-xl);
  box-shadow: 
    12px 12px 24px var(--shadow-light-1),
    -12px -12px 24px var(--shadow-light-2);
  transition: all var(--transition-base);
  position: relative;
  overflow: hidden;
}

.neumo-card::before {
  content: '';
  position: absolute;
  top: 0;
  left: 0;
  right: 0;
  height: 3px;
  background: linear-gradient(90deg, var(--primary), var(--secondary), var(--accent));
  opacity: 0;
  transition: opacity var(--transition-base);
}

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

.neumo-card:hover {
  transform: translateY(-2px);
  box-shadow: 
    16px 16px 32px var(--shadow-light-1),
    -16px -16px 32px var(--shadow-light-2);
}

/* ==========================================
   CONTENT INPUT SECTION
   ========================================== */

.content-input-section {
  margin-bottom: var(--spacing-2xl);
}

.section-label {
  display: flex;
  align-items: center;
  gap: var(--spacing-sm);
  font-weight: 700;
  font-size: var(--font-size-lg);
  margin-bottom: var(--spacing-lg);
  color: var(--text-light);
}

textarea {
  width: 100%;
  min-height: 200px;
  padding: var(--spacing-lg);
  border: none;
  border-radius: var(--radius-lg);
  background: var(--bg-light);
  color: var(--text-light);
  font-family: inherit;
  font-size: var(--font-size-base);
  line-height: 1.8;
  resize: vertical;
  box-shadow: 
    inset 8px 8px 16px var(--shadow-inset-1),
    inset -8px -8px 16px var(--shadow-inset-2);
  transition: all var(--transition-base);
}

textarea:focus {
  outline: none;
  box-shadow: 
    inset 10px 10px 20px var(--shadow-inset-1),
    inset -10px -10px 20px var(--shadow-inset-2),
    0 0 0 2px var(--primary-light);
}

textarea::placeholder {
  color: var(--text-light-secondary);
  opacity: 0.6;
}

.file-upload {
  margin-top: var(--spacing-lg);
  display: flex;
  justify-content: center;
  gap: var(--spacing-md);
}

/* ==========================================
   NEUMORPHIC BUTTONS
   ========================================== */

.neumo-btn {
  padding: var(--spacing-md) var(--spacing-xl);
  border: none;
  border-radius: var(--radius-lg);
  background: var(--bg-light);
  color: var(--text-light);
  font-size: var(--font-size-base);
  font-weight: 600;
  cursor: pointer;
  transition: all var(--transition-base);
  box-shadow: 
    8px 8px 16px var(--shadow-light-1),
    -8px -8px 16px var(--shadow-light-2);
  position: relative;
  overflow: hidden;
  display: inline-flex;
  align-items: center;
  justify-content: center;
  gap: var(--spacing-sm);
  text-decoration: none;
  user-select: none;
}

.neumo-btn::before {
  content: '';
  position: absolute;
  top: 50%;
  left: 50%;
  width: 0;
  height: 0;
  border-radius: var(--radius-full);
  background: rgba(255, 255, 255, 0.1);
  transform: translate(-50%, -50%);
  transition: width 0.6s, height 0.6s;
}

.neumo-btn:hover::before {
  width: 300px;
  height: 300px;
}

.neumo-btn:hover {
  transform: translateY(-3px);
  box-shadow: 
    12px 12px 24px var(--shadow-light-1),
    -12px -12px 24px var(--shadow-light-2);
}

.neumo-btn:active {
  transform: translateY(0);
  box-shadow: 
    inset 6px 6px 12px var(--shadow-inset-1),
    inset -6px -6px 12px var(--shadow-inset-2);
}

/* Button Variants */
.neumo-btn.primary {
  background: linear-gradient(135deg, var(--primary), var(--primary-dark));
  color: white;
  box-shadow: 
    8px 8px 16px var(--shadow-light-1),
    -8px -8px 16px var(--shadow-light-2),
    inset 0 1px 0 rgba(255, 255, 255, 0.2);
}

.neumo-btn.primary:hover {
  background: linear-gradient(135deg, var(--primary-light), var(--primary));
  box-shadow: 
    12px 12px 24px var(--shadow-light-1),
    -12px -12px 24px var(--shadow-light-2),
    0 0 30px rgba(102, 126, 234, 0.3);
}

.neumo-btn.secondary {
  padding: var(--spacing-sm) var(--spacing-lg);
  font-size: var(--font-size-sm);
}

.neumo-btn.icon-btn {
  padding: var(--spacing-md);
  font-size: var(--font-size-xl);
  min-width: 50px;
  min-height: 50px;
  border-radius: var(--radius-md);
}

.neumo-btn.full-width {
  width: 100%;
}

/* ==========================================
   THEME TOGGLE BUTTON
   ========================================== */

.theme-toggle {
  position: fixed;
  top: var(--spacing-xl);
  right: var(--spacing-xl);
  z-index: 1000;
  padding: var(--spacing-md) var(--spacing-lg);
  font-size: var(--font-size-xl);
  min-width: 60px;
  border-radius: var(--radius-xl);
  backdrop-filter: blur(10px);
  box-shadow: 
    8px 8px 20px var(--shadow-light-1),
    -8px -8px 20px var(--shadow-light-2);
}

.theme-toggle:hover {
  transform: rotate(180deg) translateY(-3px);
}

/* ==========================================
   ACTION TABS
   ========================================== */

.action-tabs {
  display: grid;
  grid-template-columns: repeat(3, 1fr);
  gap: var(--spacing-md);
  margin-bottom: var(--spacing-2xl);
  background: var(--bg-light);
  padding: var(--spacing-md);
  border-radius: var(--radius-xl);
  box-shadow: 
    inset 6px 6px 12px var(--shadow-inset-1),
    inset -6px -6px 12px var(--shadow-inset-2);
}

.tab-btn {
  padding: var(--spacing-lg) var(--spacing-md);
  border: none;
  border-radius: var(--radius-lg);
  background: transparent;
  color: var(--text-light);
  font-size: var(--font-size-base);
  font-weight: 600;
  cursor: pointer;
  transition: all var(--transition-base);
  position: relative;
  overflow: hidden;
}

.tab-btn::after {
  content: '';
  position: absolute;
  bottom: 0;
  left: 50%;
  width: 0;
  height: 3px;
  background: linear-gradient(90deg, var(--primary), var(--secondary));
  transform: translateX(-50%);
  transition: width var(--transition-base);
  border-radius: var(--radius-sm);
}

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

.tab-btn.active {
  background: var(--bg-light);
  color: var(--primary);
  box-shadow: 
    6px 6px 12px var(--shadow-light-1),
    -6px -6px 12px var(--shadow-light-2);
}

.tab-btn.active::after {
  width: 80%;
}

.tab-content {
  display: none;
  animation: fadeIn 0.4s ease-out;
}

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

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

/* ==========================================
   CONTROLS SECTION
   ========================================== */

.controls-card {
  margin-bottom: var(--spacing-xl);
}

.section-title {
  font-size: var(--font-size-2xl);
  font-weight: 700;
  margin-bottom: var(--spacing-xl);
  text-align: center;
  color: var(--text-light);
  position: relative;
  padding-bottom: var(--spacing-md);
}

.section-title::after {
  content: '';
  position: absolute;
  bottom: 0;
  left: 50%;
  transform: translateX(-50%);
  width: 60px;
  height: 4px;
  background: linear-gradient(90deg, var(--primary), var(--secondary));
  border-radius: var(--radius-sm);
}

.control-row {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(200px, 1fr));
  gap: var(--spacing-lg);
  margin-bottom: var(--spacing-lg);
}

.control-group {
  display: flex;
  flex-direction: column;
  gap: var(--spacing-sm);
}

.control-group.full-width {
  grid-column: 1 / -1;
}

.control-group label {
  font-weight: 600;
  font-size: var(--font-size-sm);
  color: var(--text-light);
  letter-spacing: 0.02em;
  text-transform: uppercase;
}

/* ==========================================
   SELECT & INPUT CONTROLS
   ========================================== */

.neumo-select {
  width: 100%;
  padding: var(--spacing-md) var(--spacing-lg);
  border: none;
  border-radius: var(--radius-md);
  background: var(--bg-light);
  color: var(--text-light);
  font-size: var(--font-size-base);
  font-family: inherit;
  cursor: pointer;
  box-shadow: 
    inset 4px 4px 8px var(--shadow-inset-1),
    inset -4px -4px 8px var(--shadow-inset-2);
  transition: all var(--transition-base);
  appearance: none;
  background-image: url("data:image/svg+xml,%3Csvg xmlns='http://www.w3.org/2000/svg' width='12' height='12' viewBox='0 0 12 12'%3E%3Cpath fill='%23667eea' d='M6 9L1 4h10z'/%3E%3C/svg%3E");
  background-repeat: no-repeat;
  background-position: right var(--spacing-md) center;
  padding-right: var(--spacing-2xl);
}

.neumo-select:focus {
  outline: none;
  box-shadow: 
    inset 6px 6px 12px var(--shadow-inset-1),
    inset -6px -6px 12px var(--shadow-inset-2),
    0 0 0 2px var(--primary-light);
}

.neumo-select:hover {
  box-shadow: 
    inset 3px 3px 6px var(--shadow-inset-1),
    inset -3px -3px 6px var(--shadow-inset-2);
}

/* ==========================================
   CHECKBOX CONTROLS
   ========================================== */

.checkbox-group {
  display: flex;
  flex-wrap: wrap;
  gap: var(--spacing-md);
  margin-top: var(--spacing-md);
}

.checkbox-label {
  display: flex;
  align-items: center;
  gap: var(--spacing-sm);
  cursor: pointer;
  padding: var(--spacing-md) var(--spacing-lg);
  border-radius: var(--radius-md);
  background: var(--bg-light);
  box-shadow: 
    6px 6px 12px var(--shadow-light-1),
    -6px -6px 12px var(--shadow-light-2);
  transition: all var(--transition-base);
  user-select: none;
  font-size: var(--font-size-sm);
  font-weight: 500;
}

.checkbox-label:hover {
  transform: translateY(-2px);
  box-shadow: 
    8px 8px 16px var(--shadow-light-1),
    -8px -8px 16px var(--shadow-light-2);
}

.checkbox-label input[type="checkbox"] {
  width: 20px;
  height: 20px;
  cursor: pointer;
  appearance: none;
  border-radius: var(--radius-sm);
  background: var(--bg-light);
  box-shadow: 
    inset 3px 3px 6px var(--shadow-inset-1),
    inset -3px -3px 6px var(--shadow-inset-2);
  position: relative;
  transition: all var(--transition-base);
}

.checkbox-label input[type="checkbox"]:checked {
  background: linear-gradient(135deg, var(--primary), var(--primary-dark));
  box-shadow: 
    inset 2px 2px 4px rgba(0, 0, 0, 0.2),
    0 0 10px rgba(102, 126, 234, 0.3);
}

.checkbox-label input[type="checkbox"]:checked::after {
  content: '✓';
  position: absolute;
  top: 50%;
  left: 50%;
  transform: translate(-50%, -50%);
  color: white;
  font-size: 14px;
  font-weight: bold;
}

/* ==========================================
   RESULT CARDS
   ========================================== */

.result-card {
  animation: slideInUp 0.5s ease-out;
}

@keyframes slideInUp {
  from {
    opacity: 0;
    transform: translateY(40px);
  }
  to {
    opacity: 1;
    transform: translateY(0);
  }
}

.result-header {
  display: flex;
  justify-content: space-between;
  align-items: center;
  margin-bottom: var(--spacing-xl);
  padding-bottom: var(--spacing-lg);
  border-bottom: 2px solid var(--shadow-light-1);
}

.result-header h3 {
  font-size: var(--font-size-2xl);
  font-weight: 700;
  background: linear-gradient(135deg, var(--primary), var(--secondary));
  -webkit-background-clip: text;
  -webkit-text-fill-color: transparent;
  background-clip: text;
}

.action-buttons {
  display: flex;
  gap: var(--spacing-sm);
  flex-wrap: wrap;
}

.result-content {
  line-height: 1.9;
  font-size: var(--font-size-base);
  color: var(--text-light);
}

/* ==========================================
   QUIZ COMPONENTS
   ========================================== */

.quiz-progress {
  font-size: var(--font-size-sm);
  font-weight: 600;
  color: var(--text-light-secondary);
  padding: var(--spacing-sm) var(--spacing-md);
  background: var(--bg-light);
  border-radius: var(--radius-md);
  box-shadow: 
    inset 3px 3px 6px var(--shadow-inset-1),
    inset -3px -3px 6px var(--shadow-inset-2);
}

.quiz-question {
  margin-bottom: var(--spacing-xl);
  padding: var(--spacing-xl);
  border-radius: var(--radius-lg);
  background: var(--bg-light);
  box-shadow: 
    8px 8px 16px var(--shadow-light-1),
    -8px -8px 16px var(--shadow-light-2);
  transition: all var(--transition-base);
}

.quiz-question:hover {
  transform: translateX(4px);
  box-shadow: 
    12px 12px 24px var(--shadow-light-1),
    -12px -12px 24px var(--shadow-light-2);
}

.quiz-question-header {
  display: flex;
  justify-content: space-between;
  align-items: flex-start;
  gap: var(--spacing-md);
  margin-bottom: var(--spacing-lg);
}

.question-text {
  font-size: var(--font-size-lg);
  font-weight: 600;
  line-height: 1.7;
  flex: 1;
  color: var(--text-light);
}

.question-type-badge {
  padding: var(--spacing-sm) var(--spacing-md);
  border-radius: var(--radius-xl);
  font-size: var(--font-size-xs);
  font-weight: 700;
  text-transform: uppercase;
  letter-spacing: 0.05em;
  background: linear-gradient(135deg, var(--info), var(--info-dark));
  color: white;
  white-space: nowrap;
  box-shadow: 0 4px 12px rgba(33, 150, 243, 0.3);
}

.quiz-options {
  display: flex;
  flex-direction: column;
  gap: var(--spacing-md);
  margin: var(--spacing-lg) 0;
}

.quiz-option {
  padding: var(--spacing-lg) var(--spacing-xl);
  border-radius: var(--radius-md);
  background: var(--bg-light);
  cursor: pointer;
  transition: all var(--transition-base);
  box-shadow: 
    6px 6px 12px var(--shadow-light-1),
    -6px -6px 12px var(--shadow-light-2);
  border: 2px solid transparent;
  font-size: var(--font-size-base);
  line-height: 1.6;
  position: relative;
  overflow: hidden;
}

.quiz-option::before {
  content: '';
  position: absolute;
  left: 0;
  top: 0;
  bottom: 0;
  width: 4px;
  background: var(--primary);
  transform: scaleY(0);
  transition: transform var(--transition-base);
}

.quiz-option:hover {
  transform: translateX(8px);
  box-shadow: 
    10px 10px 20px var(--shadow-light-1),
    -10px -10px 20px var(--shadow-light-2);
}

.quiz-option:hover::before {
  transform: scaleY(1);
}

.quiz-option.selected {
  border-color: var(--primary);
  background: linear-gradient(135deg, rgba(102, 126, 234, 0.15), rgba(102, 126, 234, 0.05));
  box-shadow: 
    inset 4px 4px 8px var(--shadow-inset-1),
    inset -4px -4px 8px var(--shadow-inset-2),
    0 0 20px rgba(102, 126, 234, 0.2);
}

.quiz-option.correct {
  border-color: var(--success);
  background: linear-gradient(135deg, rgba(76, 175, 80, 0.15), rgba(76, 175, 80, 0.05));
  box-shadow: 
    inset 4px 4px 8px rgba(76, 175, 80, 0.1),
    0 0 20px rgba(76, 175, 80, 0.2);
}

.quiz-option.correct::before {
  background: var(--success);
  transform: scaleY(1);
}

.quiz-option.incorrect {
  border-color: var(--danger);
  background: linear-gradient(135deg, rgba(244, 67, 54, 0.15), rgba(244, 67, 54, 0.05));
  box-shadow: 
    inset 4px 4px 8px rgba(244, 67, 54, 0.1),
    0 0 20px rgba(244, 67, 54, 0.2);
}

.quiz-option.incorrect::before {
  background: var(--danger);
  transform: scaleY(1);
}

.quiz-input {
  width: 100%;
  padding: var(--spacing-lg);
  border: none;
  border-radius: var(--radius-md);
  background: var(--bg-light);
  color: var(--text-light);
  font-size: var(--font-size-base);
  font-family: inherit;
  box-shadow: 
    inset 6px 6px 12px var(--shadow-inset-1),
    inset -6px -6px 12px var(--shadow-inset-2);
  transition: all var(--transition-base);
}

.quiz-input:focus {
  outline: none;
  box-shadow: 
    inset 8px 8px 16px var(--shadow-inset-1),
    inset -8px -8px 16px var(--shadow-inset-2),
    0 0 0 2px var(--primary-light);
}

/* Hint Section */
.hint-section {
  margin-top: var(--spacing-lg);
}

.hint-btn {
  padding: var(--spacing-sm) var(--spacing-lg);
  font-size: var(--font-size-sm);
}

.hint-content {
  margin-top: var(--spacing-md);
  padding: var(--spacing-lg);
  border-radius: var(--radius-md);
  background: linear-gradient(135deg, rgba(255, 152, 0, 0.1), rgba(255, 152, 0, 0.05));
  border-left: 4px solid var(--warning);
  font-size: var(--font-size-sm);
  line-height: 1.7;
  color: var(--text-light);
  box-shadow: 
    4px 4px 8px var(--shadow-light-1),
    -4px -4px 8px var(--shadow-light-2);
  animation: slideInLeft 0.3s ease-out;
}

@keyframes slideInLeft {
  from {
    opacity: 0;
    transform: translateX(-20px);
  }
  to {
    opacity: 1;
    transform: translateX(0);
  }
}

.explanation {
  margin-top: var(--spacing-lg);
  padding: var(--spacing-lg);
  border-radius: var(--radius-md);
  background: linear-gradient(135deg, rgba(33, 150, 243, 0.1), rgba(33, 150, 243, 0.05));
  border-left: 4px solid var(--info);
  font-size: var(--font-size-sm);
  line-height: 1.7;
  color: var(--text-light);
  box-shadow: 
    4px 4px 8px var(--shadow-light-1),
    -4px -4px 8px var(--shadow-light-2);
  animation: slideInLeft 0.3s ease-out;
}

/* ==========================================
   QUIZ RESULTS & SCORE
   ========================================== */

.quiz-score {
  text-align: center;
  padding: var(--spacing-2xl);
  margin-bottom: var(--spacing-xl);
  border-radius: var(--radius-xl);
  background: linear-gradient(135deg, var(--success), var(--success-dark));
  color: white;
  box-shadow: 
    12px 12px 24px var(--shadow-light-1),
    -12px -12px 24px var(--shadow-light-2),
    inset 0 1px 0 rgba(255, 255, 255, 0.3),
    0 0 40px rgba(76, 175, 80, 0.4);
  position: relative;
  overflow: hidden;
}

.quiz-score::before {
  content: '';
  position: absolute;
  top: -50%;
  left: -50%;
  width: 200%;
  height: 200%;
  background: radial-gradient(circle, rgba(255, 255, 255, 0.1) 0%, transparent 70%);
  animation: rotate 10s linear infinite;
}

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

.quiz-score h2 {
  font-size: clamp(var(--font-size-4xl), 8vw, var(--font-size-5xl));
  font-weight: 800;
  margin-bottom: var(--spacing-sm);
  text-shadow: 2px 2px 8px rgba(0, 0, 0, 0.2);
  position: relative;
  z-index: 1;
}

.quiz-score p {
  font-size: var(--font-size-xl);
  opacity: 0.95;
  font-weight: 600;
  position: relative;
  z-index: 1;
}

/* ==========================================
   TIMER DISPLAY
   ========================================== */

.timer-display {
  font-size: var(--font-size-2xl);
  font-weight: 800;
  color: var(--primary);
  padding: var(--spacing-md) var(--spacing-xl);
  border-radius: var(--radius-md);
  background: var(--bg-light);
  box-shadow: 
    inset 4px 4px 8px var(--shadow-inset-1),
    inset -4px -4px 8px var(--shadow-inset-2);
  font-variant-numeric: tabular-nums;
  letter-spacing: 0.05em;
  min-width: 100px;
  text-align: center;
}

.timer-display.warning {
  color: var(--danger);
  animation: timerPulse 1s ease-in-out infinite;
  box-shadow: 
    inset 4px 4px 8px rgba(244, 67, 54, 0.2),
    inset -4px -4px 8px var(--shadow-inset-2),
    0 0 20px rgba(244, 67, 54, 0.3);
}

@keyframes timerPulse {
  0%, 100% { 
    transform: scale(1); 
    filter: brightness(1);
  }
  50% { 
    transform: scale(1.08); 
    filter: brightness(1.2);
  }
}

/* ==========================================
   LOADING OVERLAY
   ========================================== */

.loading-overlay {
  position: fixed;
  top: 0;
  left: 0;
  right: 0;
  bottom: 0;
  background: rgba(0, 0, 0, 0.8);
  backdrop-filter: blur(8px);
  display: flex;
  flex-direction: column;
  justify-content: center;
  align-items: center;
  z-index: 9999;
  animation: fadeIn 0.3s ease-out;
}

.loading-spinner {
  width: 80px;
  height: 80px;
  border: 8px solid var(--shadow-light-1);
  border-top-color: var(--primary);
  border-right-color: var(--secondary);
  border-radius: var(--radius-full);
  animation: spin 1s cubic-bezier(0.68, -0.55, 0.265, 1.55) infinite;
  box-shadow: 0 0 40px rgba(102, 126, 234, 0.4);
}

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

.loading-overlay p {
  margin-top: var(--spacing-xl);
  color: white;
  font-size: var(--font-size-lg);
  font-weight: 600;
  animation: pulse 2s ease-in-out infinite;
}

@keyframes pulse {
  0%, 100% { opacity: 1; }
  50% { opacity: 0.6; }
}

/* ==========================================
   UTILITY CLASSES
   ========================================== */

.hidden {
  display: none !important;
}

.info-text {
  text-align: center;
  color: var(--text-light-secondary);
  margin-bottom: var(--spacing-xl);
  font-size: var(--font-size-base);
  line-height: 1.6;
  padding: var(--spacing-lg);
  border-radius: var(--radius-md);
  background: var(--bg-light);
  box-shadow: 
    inset 3px 3px 6px var(--shadow-inset-1),
    inset -3px -3px 6px var(--shadow-inset-2);
}

/* ==========================================
   RESPONSIVE DESIGN - TABLET (768px - 1024px)
   ========================================== */

@media (max-width: 1024px) {
  :root {
    --spacing-xl: 1.5rem;
    --spacing-2xl: 2.5rem;
  }

  .container {
    max-width: 900px;
  }

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

  .control-row {
    grid-template-columns: repeat(auto-fit, minmax(180px, 1fr));
  }

  .quiz-question {
    padding: var(--spacing-lg);
  }

  .result-header {
    flex-wrap: wrap;
    gap: var(--spacing-md);
  }

  .action-buttons {
    width: 100%;
    justify-content: center;
  }
}

/* ==========================================
   RESPONSIVE DESIGN - MOBILE (768px and below)
   ========================================== */

@media (max-width: 768px) {
  :root {
    --font-size-3xl: 1.5rem;
    --font-size-4xl: 1.875rem;
    --font-size-5xl: 2.25rem;
    --spacing-xl: 1.25rem;
    --spacing-2xl: 2rem;
  }

  body {
    padding: var(--spacing-md);
  }

  .container {
    max-width: 100%;
  }

  /* Header */
  .app-header {
    padding: var(--spacing-xl) var(--spacing-sm);
    margin-bottom: var(--spacing-xl);
  }

  .app-header h1 {
    font-size: var(--font-size-3xl);
  }

  .tagline {
    font-size: var(--font-size-base);
  }

  /* Theme Toggle */
  .theme-toggle {
    top: var(--spacing-md);
    right: var(--spacing-md);
    padding: var(--spacing-sm) var(--spacing-md);
    min-width: 50px;
    font-size: var(--font-size-lg);
    border-radius: var(--radius-md);
  }

  /* Cards */
  .neumo-card {
    padding: var(--spacing-lg);
    margin-bottom: var(--spacing-lg);
    border-radius: var(--radius-lg);
  }

  /* Textarea */
  textarea {
    min-height: 150px;
    padding: var(--spacing-md);
    font-size: var(--font-size-sm);
  }

  /* Tabs */
  .action-tabs {
    grid-template-columns: 1fr;
    gap: var(--spacing-sm);
    padding: var(--spacing-sm);
  }

  .tab-btn {
    padding: var(--spacing-md);
    font-size: var(--font-size-sm);
  }

  /* Controls */
  .section-title {
    font-size: var(--font-size-xl);
    margin-bottom: var(--spacing-lg);
  }

  .control-row {
    grid-template-columns: 1fr;
    gap: var(--spacing-md);
  }

  .control-group {
    min-width: 100%;
  }

  /* Checkboxes */
  .checkbox-group {
    flex-direction: column;
    gap: var(--spacing-sm);
  }

  .checkbox-label {
    width: 100%;
    justify-content: flex-start;
  }

  /* Buttons */
  .neumo-btn {
    padding: var(--spacing-md) var(--spacing-lg);
    font-size: var(--font-size-sm);
  }

  .neumo-btn.icon-btn {
    padding: var(--spacing-sm);
    min-width: 44px;
    min-height: 44px;
    font-size: var(--font-size-lg);
  }

  .file-upload {
    flex-direction: column;
  }

  /* Results */
  .result-header {
    flex-direction: column;
    align-items: flex-start;
    gap: var(--spacing-md);
  }

  .result-header h3 {
    font-size: var(--font-size-xl);
  }

  .action-buttons {
    width: 100%;
    justify-content: flex-start;
  }

  .result-content {
    font-size: var(--font-size-sm);
    line-height: 1.7;
  }

  /* Quiz */
  .quiz-question {
    padding: var(--spacing-md);
    margin-bottom: var(--spacing-lg);
  }

  .quiz-question-header {
    flex-direction: column;
    gap: var(--spacing-sm);
    align-items: flex-start;
  }

  .question-text {
    font-size: var(--font-size-base);
  }

  .question-type-badge {
    align-self: flex-start;
    font-size: 0.65rem;
    padding: 0.375rem var(--spacing-sm);
  }

  .quiz-option {
    padding: var(--spacing-md);
    font-size: var(--font-size-sm);
  }

  .quiz-option:hover {
    transform: translateX(4px);
  }

  .quiz-input {
    padding: var(--spacing-md);
    font-size: var(--font-size-sm);
  }

  .hint-content,
  .explanation {
    padding: var(--spacing-md);
    font-size: var(--font-size-xs);
  }

  /* Score */
  .quiz-score {
    padding: var(--spacing-xl);
    margin-bottom: var(--spacing-lg);
  }

  .quiz-score h2 {
    font-size: var(--font-size-4xl);
  }

  .quiz-score p {
    font-size: var(--font-size-base);
  }

  /* Timer */
  .timer-display {
    font-size: var(--font-size-xl);
    padding: var(--spacing-sm) var(--spacing-lg);
    min-width: 90px;
  }

  /* Loading */
  .loading-spinner {
    width: 60px;
    height: 60px;
    border-width: 6px;
  }

  .loading-overlay p {
    font-size: var(--font-size-base);
  }
}

/* ==========================================
   RESPONSIVE DESIGN - SMALL MOBILE (480px and below)
   ========================================== */

@media (max-width: 480px) {
  :root {
    --spacing-md: 0.75rem;
    --spacing-lg: 1rem;
    --spacing-xl: 1rem;
    --spacing-2xl: 1.5rem;
  }

  body {
    padding: var(--spacing-sm);
  }

  .app-header {
    padding: var(--spacing-lg) var(--spacing-xs);
  }

  .app-header h1 {
    font-size: var(--font-size-2xl);
  }

  .tagline {
    font-size: var(--font-size-sm);
  }

  .theme-toggle {
    top: var(--spacing-sm);
    right: var(--spacing-sm);
    padding: var(--spacing-sm);
    min-width: 44px;
    font-size: var(--font-size-base);
  }

  .neumo-card {
    padding: var(--spacing-md);
    border-radius: var(--radius-md);
  }

  textarea {
    min-height: 120px;
    padding: var(--spacing-sm);
    font-size: 0.8rem;
  }

  .section-title {
    font-size: var(--font-size-lg);
    margin-bottom: var(--spacing-md);
  }

  .neumo-btn {
    padding: var(--spacing-sm) var(--spacing-md);
    font-size: 0.8rem;
  }

  .quiz-question {
    padding: var(--spacing-sm);
    margin-bottom: var(--spacing-md);
  }

  .question-text {
    font-size: var(--font-size-sm);
  }

  .quiz-option {
    padding: var(--spacing-sm) var(--spacing-md);
    font-size: 0.8rem;
  }

  .quiz-score {
    padding: var(--spacing-lg);
  }

  .quiz-score h2 {
    font-size: var(--font-size-3xl);
  }

  .quiz-score p {
    font-size: var(--font-size-sm);
  }

  .timer-display {
    font-size: var(--font-size-lg);
    padding: var(--spacing-sm) var(--spacing-md);
    min-width: 80px;
  }

  .result-header h3 {
    font-size: var(--font-size-lg);
  }

  .action-buttons {
    gap: 0.375rem;
  }

  .neumo-btn.icon-btn {
    padding: var(--spacing-sm);
    min-width: 40px;
    min-height: 40px;
    font-size: var(--font-size-base);
  }
}

/* ==========================================
   RESPONSIVE DESIGN - LARGE DESKTOP (1440px+)
   ========================================== */

@media (min-width: 1440px) {
  .container {
    max-width: 1400px;
  }

  .app-header h1 {
    font-size: var(--font-size-5xl);
  }

  .neumo-card {
    padding: var(--spacing-2xl);
  }

  .quiz-question {
    padding: var(--spacing-2xl);
  }

  .control-row {
    grid-template-columns: repeat(auto-fit, minmax(250px, 1fr));
  }

  .result-content {
    font-size: var(--font-size-lg);
  }
}

/* ==========================================
   RESPONSIVE DESIGN - 4K (2560px+)
   ========================================== */

@media (min-width: 2560px) {
  :root {
    --font-size-base: 1.125rem;
    --font-size-lg: 1.375rem;
    --font-size-xl: 1.5rem;
    --font-size-2xl: 1.875rem;
    --font-size-3xl: 2.25rem;
    --font-size-4xl: 3rem;
    --font-size-5xl: 4rem;
  }

  .container {
    max-width: 1800px;
  }

  .neumo-card {
    padding: var(--spacing-3xl);
  }

  .quiz-question {
    padding: var(--spacing-3xl);
  }

  .neumo-btn {
    padding: var(--spacing-lg) var(--spacing-2xl);
    font-size: var(--font-size-lg);
  }
}

/* ==========================================
   PRINT STYLES
   ========================================== */

@media print {
  body {
    background: white;
    color: black;
  }

  .theme-toggle,
  .action-tabs,
  .neumo-btn,
  .loading-overlay {
    display: none !important;
  }

  .neumo-card {
    box-shadow: none;
    border: 1px solid #ddd;
    page-break-inside: avoid;
  }

  .quiz-question {
    page-break-inside: avoid;
  }
}

/* ==========================================
   ACCESSIBILITY IMPROVEMENTS
   ========================================== */

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

/* Focus Styles for Keyboard Navigation */
*:focus-visible {
  outline: 3px solid var(--primary);
  outline-offset: 3px;
}

/* High Contrast Mode Support */
@media (prefers-contrast: high) {
  .neumo-card,
  .neumo-btn,
  .quiz-option {
    border: 2px solid var(--text-light);
  }
}

/* ==========================================
   SCROLLBAR STYLING
   ========================================== */

::-webkit-scrollbar {
  width: 12px;
  height: 12px;
}

::-webkit-scrollbar-track {
  background: var(--bg-light);
  box-shadow: inset 2px 2px 4px var(--shadow-inset-1);
}

::-webkit-scrollbar-thumb {
  background: linear-gradient(135deg, var(--primary), var(--secondary));
  border-radius: var(--radius-md);
  box-shadow: 0 2px 8px rgba(0, 0, 0, 0.2);
}

::-webkit-scrollbar-thumb:hover {
  background: linear-gradient(135deg, var(--primary-light), var(--primary));
}

/* Firefox Scrollbar */
* {
  scrollbar-width: thin;
  scrollbar-color: var(--primary) var(--bg-light);
}