/* ============================================================
   STUDY BUDDY - PROFESSIONAL CSS STYLESHEET
   ============================================================ */

/* ============================================================
   CSS VARIABLES & ROOT SETTINGS
   ============================================================ */

:root {
  --primary-color: #2563eb;
  --primary-dark: #1e40af;
  --primary-light: #3b82f6;
  --success-color: #059669;
  --warning-color: #f59e0b;
  --danger-color: #dc2626;
  --gray-50: #f9fafb;
  --gray-100: #f3f4f6;
  --gray-200: #e5e7eb;
  --gray-300: #d1d5db;
  --gray-400: #9ca3af;
  --gray-500: #6b7280;
  --gray-600: #4b5563;
  --gray-700: #374151;
  --gray-800: #1f2937;
  --gray-900: #111827;

  --text-primary: #1e293b;
  --text-secondary: #64748b;

  --spacing-xs: 4px;
  --spacing-sm: 8px;
  --spacing-md: 12px;
  --spacing-lg: 16px;
  --spacing-xl: 20px;
  --spacing-2xl: 24px;
  --spacing-3xl: 32px;
  --spacing-4xl: 40px;

  --border-radius-sm: 6px;
  --border-radius-md: 10px;
  --border-radius-lg: 12px;
  --border-radius-xl: 16px;

  --shadow-sm: 0 1px 2px rgba(0, 0, 0, 0.05);
  --shadow-md: 0 4px 6px rgba(0, 0, 0, 0.1);
  --shadow-lg: 0 8px 16px rgba(0, 0, 0, 0.1);
  --shadow-xl: 0 12px 24px rgba(0, 0, 0, 0.15);

  --transition-fast: 150ms cubic-bezier(0.4, 0, 0.2, 1);
  --transition-base: 200ms cubic-bezier(0.4, 0, 0.2, 1);
  --transition-slow: 300ms cubic-bezier(0.4, 0, 0.2, 1);
}

/* ============================================================
   GLOBAL STYLES
   ============================================================ */

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

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

body {
  font-family: -apple-system, BlinkMacSystemFont, 'Segoe UI', 'Helvet Neue', sans-serif;
  font-size: 16px;
  line-height: 1.6;
  color: var(--text-primary);
  background: linear-gradient(135deg, #f5f7fa 0%, #c3cfe2 100%);
  min-height: 100vh;
  background-attachment: fixed;
}

body::-webkit-scrollbar {
  width: 8px;
}

body::-webkit-scrollbar-track {
  background: var(--gray-100);
}

body::-webkit-scrollbar-thumb {
  background: var(--gray-300);
  border-radius: 4px;
}

body::-webkit-scrollbar-thumb:hover {
  background: var(--gray-400);
}

/* ============================================================
   ROOT CONTAINER
   ============================================================ */

#root {
  display: flex;
  justify-content: center;
  align-items: flex-start;
  min-height: 100vh;
  padding: var(--spacing-md);
  width: 100%;
}

/* ============================================================
   BUTTON STYLES
   ============================================================ */

button {
  font-family: inherit;
  font-size: inherit;
  border: none;
  border-radius: var(--border-radius-md);
  cursor: pointer;
  transition: all var(--transition-base);
  font-weight: 600;
  display: inline-flex;
  align-items: center;
  justify-content: center;
  gap: var(--spacing-sm);
  outline: none;
  white-space: nowrap;
  text-align: center;
}

button:disabled {
  opacity: 0.5;
  cursor: not-allowed;
}

button:not(:disabled):hover {
  transform: translateY(-1px);
  box-shadow: var(--shadow-md);
}

button:not(:disabled):active {
  transform: translateY(0);
}

/* Button Variants */
.btn {
  padding: var(--spacing-sm) var(--spacing-xl);
  font-size: 14px;
  font-weight: 600;
  border-radius: var(--border-radius-md);
  white-space: nowrap;
  text-align: center;
  border: none;
  cursor: pointer;
  transition: all var(--transition-base);
  display: inline-flex;
  align-items: center;
  justify-content: center;
  gap: var(--spacing-sm);
  min-height: 40px;
}

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

.btn-primary:hover:not(:disabled) {
  background: var(--primary-dark);
  box-shadow: 0 4px 12px rgba(37, 99, 235, 0.3);
}

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

.btn-success:hover:not(:disabled) {
  background: #047857;
  box-shadow: 0 4px 12px rgba(5, 150, 105, 0.3);
}

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

.btn-warning:hover:not(:disabled) {
  background: #d97706;
  box-shadow: 0 4px 12px rgba(245, 158, 11, 0.3);
}

.btn-gray {
  background: var(--gray-500);
  color: white;
}

.btn-gray:hover:not(:disabled) {
  background: var(--gray-600);
  box-shadow: 0 4px 12px rgba(107, 114, 128, 0.3);
}

/* ============================================================
   INPUT STYLES
   ============================================================ */

input[type="text"] {
  font-family: inherit;
  padding: var(--spacing-sm) var(--spacing-md);
  border: 2px solid var(--gray-200);
  border-radius: var(--border-radius-sm);
  font-size: 14px;
  transition: all var(--transition-base);
  outline: none;
}

input[type="text"]:focus {
  border-color: var(--primary-color);
  box-shadow: 0 0 0 3px rgba(37, 99, 235, 0.1);
}

input[type="text"]:disabled {
  background: var(--gray-100);
  cursor: not-allowed;
}

/* ============================================================
   HOME SCREEN
   ============================================================ */

.home-screen {
  max-width: 1200px;
  width: 100%;
  padding: var(--spacing-3xl) var(--spacing-xl);
  animation: fadeIn var(--transition-slow) ease-out;
}

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

.home-header {
  text-align: center;
  margin-bottom: var(--spacing-4xl);
}

.home-header h1 {
  font-size: clamp(28px, 7vw, 48px);
  font-weight: 800;
  color: var(--gray-900);
  margin-bottom: var(--spacing-md);
  letter-spacing: -0.5px;
}

.home-header p {
  font-size: clamp(16px, 4vw, 20px);
  color: var(--text-secondary);
  font-weight: 500;
}

/* Home Stats */
.home-stats {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(150px, 1fr));
  gap: var(--spacing-lg);
  margin-bottom: var(--spacing-4xl);
}

.stat-card {
  padding: var(--spacing-2xl);
  border-radius: var(--border-radius-lg);
  background: white;
  border: 1px solid var(--gray-200);
  text-align: center;
  transition: all var(--transition-base);
  box-shadow: var(--shadow-sm);
}

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

.stat-value {
  font-size: clamp(24px, 5vw, 36px);
  font-weight: 800;
  color: var(--primary-color);
  margin: 0 0 var(--spacing-sm);
}

.stat-label {
  font-size: 14px;
  color: var(--text-secondary);
  font-weight: 600;
  margin: 0;
}

/* Modules Grid */
.modules-grid {
  display: grid;
  grid-template-columns: repeat(3, 1fr);
  gap: var(--spacing-lg);
}

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

@media (max-width: 768px) {
  .modules-grid {
    grid-template-columns: repeat(2, 1fr);
  }
}

@media (max-width: 480px) {
  .modules-grid {
    grid-template-columns: 1fr;
  }
}

.module-card {
  padding: var(--spacing-xl);
  border-radius: var(--border-radius-lg);
  border: none;
  cursor: pointer;
  text-align: center;
  color: white;
  font-weight: 600;
  transition: all var(--transition-base);
  box-shadow: var(--shadow-md);
  position: relative;
  overflow: hidden;
  display: flex;
  flex-direction: column;
  align-items: center;
  justify-content: center;
  gap: var(--spacing-md);
  min-height: 240px;
  width: 100%;
}

.module-card::before {
  content: '';
  position: absolute;
  top: -50%;
  right: -50%;
  width: 100%;
  height: 100%;
  background: rgba(255, 255, 255, 0.1);
  border-radius: 50%;
  transition: all var(--transition-slow);
}

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

.module-card:hover::before {
  top: -20%;
  right: -20%;
}

.module-card-icon {
  font-size: 48px;
  margin: 0;
  display: block;
  animation: float 3s ease-in-out infinite;
  line-height: 1;
}

.module-card:nth-child(2) .module-card-icon {
  animation-delay: 0.2s;
}

.module-card:nth-child(3) .module-card-icon {
  animation-delay: 0.4s;
}

.module-card:nth-child(4) .module-card-icon {
  animation-delay: 0.6s;
}

@keyframes float {
  0%, 100% {
    transform: translateY(0px);
  }
  50% {
    transform: translateY(-8px);
  }
}

.module-card-title {
  font-size: clamp(15px, 3vw, 17px);
  font-weight: 700;
  margin: 0;
  position: relative;
  z-index: 1;
  line-height: 1.5;
  word-wrap: break-word;
  overflow-wrap: break-word;
  word-break: break-word;
  hyphens: auto;
  max-width: 100%;
}

.module-card-count {
  font-size: 13px;
  opacity: 0.9;
  margin: 0;
  position: relative;
  z-index: 1;
}

/* ============================================================
   MODULE SCREEN - HEADER
   ============================================================ */

.module-wrapper {
  width: 100%;
  min-height: 100vh;
  max-width: 1200px;
  display: flex;
  flex-direction: column;
  background: white;
  border-radius: var(--border-radius-lg);
  box-shadow: var(--shadow-lg);
  overflow: visible;
  animation: slideUp var(--transition-slow) ease-out;
}

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

.module-header {
  color: white;
  padding: var(--spacing-2xl) var(--spacing-xl);
  position: relative;
  overflow: visible;
  background-size: cover;
  background-position: center;
  min-height: auto;
}

.module-header::before {
  content: '';
  position: absolute;
  top: -50%;
  right: -10%;
  width: 400px;
  height: 400px;
  background: rgba(255, 255, 255, 0.1);
  border-radius: 50%;
  animation: pulse 4s ease-in-out infinite;
}

@keyframes pulse {
  0%, 100% {
    transform: scale(1);
  }
  50% {
    transform: scale(1.1);
  }
}

.module-header::after {
  content: '';
  position: absolute;
  bottom: -50%;
  left: -10%;
  width: 300px;
  height: 300px;
  background: rgba(255, 255, 255, 0.08);
  border-radius: 50%;
}

.module-header-content {
  max-width: 1200px;
  margin: 0 auto;
  position: relative;
  z-index: 1;
  width: 100%;
  padding: 0 var(--spacing-lg);
}

.module-header-top {
  display: flex;
  justify-content: space-between;
  align-items: center;
  margin-bottom: var(--spacing-lg);
  gap: var(--spacing-lg);
  min-height: 36px;
  width: 100%;
}

.module-header-top button {
  background: rgba(255, 255, 255, 0.2);
  color: white;
  padding: var(--spacing-sm) var(--spacing-lg);
  border-radius: var(--border-radius-sm);
  font-size: 13px;
  font-weight: 600;
  transition: all var(--transition-base);
  backdrop-filter: blur(10px);
  white-space: nowrap;
  text-overflow: ellipsis;
  overflow: visible;
  border: none;
  cursor: pointer;
  min-height: 36px;
  display: inline-flex;
  align-items: center;
  justify-content: center;
}

.module-header-top button:hover {
  background: rgba(255, 255, 255, 0.3);
  transform: translateX(-2px);
}

.module-header-top span {
  font-size: 12px;
  opacity: 0.9;
  font-weight: 600;
  color: white;
  white-space: nowrap;
}

.module-header h2 {
  font-size: clamp(24px, 5vw, 32px);
  font-weight: 700;
  margin: var(--spacing-md) 0 var(--spacing-sm);
  letter-spacing: -0.5px;
  color: white;
  text-shadow: 0 2px 4px rgba(0, 0, 0, 0.1);
  line-height: 1.2;
}

.module-header p {
  font-size: 14px;
  opacity: 0.95;
  margin: 0;
  font-weight: 500;
  color: white;
}

/* ============================================================
   TAB NAVIGATION
   ============================================================ */

.section-tabs {
  background: white;
  border-bottom: 2px solid var(--gray-200);
  padding: 0 var(--spacing-xl);
  overflow-x: auto;
  overflow-y: hidden;
  width: 100%;
  flex-shrink: 0;
}

.section-tabs::-webkit-scrollbar {
  height: 3px;
}

.section-tabs::-webkit-scrollbar-track {
  background: transparent;
}

.section-tabs::-webkit-scrollbar-thumb {
  background: var(--gray-300);
  border-radius: 3px;
}

.tabs-container {
  max-width: 1200px;
  margin: 0 auto;
  display: flex;
  gap: var(--spacing-sm);
  padding: var(--spacing-md) 0;
}

.tab-button {
  padding: var(--spacing-md) var(--spacing-lg);
  border: none;
  border-bottom: 3px solid transparent;
  background: transparent;
  cursor: pointer;
  font-size: 13px;
  font-weight: 600;
  color: var(--text-secondary);
  white-space: nowrap;
  transition: all var(--transition-base);
  position: relative;
  text-transform: uppercase;
  letter-spacing: 0.5px;
}

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

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

/* ============================================================
   CONTENT WRAPPER
   ============================================================ */

.content-wrapper {
  max-width: 1200px;
  margin: 0 auto;
  padding: var(--spacing-2xl) var(--spacing-xl);
  width: 100%;
  flex: 1;
  overflow: visible;
}

.section-title {
  font-size: clamp(18px, 4vw, 24px);
  font-weight: 700;
  color: var(--gray-900);
  margin: 0 0 var(--spacing-sm);
  letter-spacing: -0.5px;
}

.section-info {
  font-size: 13px;
  color: var(--text-secondary);
  margin: 0 0 var(--spacing-2xl);
  font-weight: 500;
}

/* ============================================================
   FLASHCARD SECTION
   ============================================================ */

.flashcard-container {
  text-align: center;
}

.flashcard-progress {
  font-size: 13px;
  color: var(--text-secondary);
  margin-bottom: var(--spacing-lg);
  font-weight: 600;
  background: var(--gray-100);
  padding: var(--spacing-md) var(--spacing-lg);
  border-radius: var(--border-radius-md);
}

.flashcard {
  min-height: 240px;
  padding: var(--spacing-3xl) var(--spacing-2xl);
  border-radius: var(--border-radius-xl);
  cursor: pointer;
  color: white;
  display: flex;
  flex-direction: column;
  align-items: center;
  justify-content: center;
  gap: var(--spacing-lg);
  font-size: clamp(16px, 3vw, 20px);
  line-height: 1.8;
  transition: all var(--transition-base);
  box-shadow: var(--shadow-lg);
  margin-bottom: var(--spacing-2xl);
  user-select: none;
  text-shadow: 0 1px 2px rgba(0, 0, 0, 0.1);
  font-weight: 500;
  position: relative;
  overflow: hidden;
  text-align: center;
}

.flashcard::before {
  content: '';
  position: absolute;
  top: 0;
  left: 0;
  right: 0;
  bottom: 0;
  background: linear-gradient(135deg, rgba(255,255,255,0.1) 0%, rgba(255,255,255,0) 100%);
  pointer-events: none;
}

.flashcard.front {
  background: linear-gradient(135deg, #2563eb 0%, #1e40af 100%);
}

.flashcard.back {
  background: linear-gradient(135deg, #059669 0%, #047857 100%);
}

.flashcard:hover {
  transform: translateY(-4px) scale(1.01);
  box-shadow: var(--shadow-xl);
}

.flashcard:active {
  transform: translateY(-2px) scale(1.005);
}

.flashcard-label {
  font-size: 0.7em;
  opacity: 0.75;
  display: inline-block;
  margin-top: 0;
  font-weight: 400;
  letter-spacing: 0.5px;
  text-transform: uppercase;
  text-shadow: 0 1px 2px rgba(0, 0, 0, 0.2);
}

.flashcard-content {
  display: flex;
  flex-direction: column;
  align-items: center;
  justify-content: center;
  width: 100%;
}

/* ============================================================
   ITEM CONTAINER (True/False, MCQ)
   ============================================================ */

.item-container {
  padding: var(--spacing-lg);
  margin-bottom: var(--spacing-lg);
  border-radius: var(--border-radius-md);
  border: 2px solid var(--gray-200);
  background: white;
  transition: all var(--transition-base);
  animation: slideIn var(--transition-base) ease-out;
}

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

.item-container:hover {
  border-color: var(--gray-300);
  box-shadow: var(--shadow-sm);
}

.item-container.answered {
  border-color: transparent;
}

.item-container.answered.correct {
  border-color: var(--success-color);
  background: rgba(5, 150, 105, 0.05);
}

.item-container.answered.incorrect {
  border-color: var(--danger-color);
  background: rgba(220, 38, 38, 0.05);
}

.item-question {
  font-size: 15px;
  margin-bottom: var(--spacing-lg);
  color: var(--text-primary);
  font-weight: 600;
  line-height: 1.6;
}

.button-grid {
  display: flex;
  flex-direction: column;
  gap: var(--spacing-md);
}

.option-button {
  padding: var(--spacing-md) var(--spacing-lg);
  border-radius: var(--border-radius-md);
  text-align: left;
  border: 2px solid var(--gray-200);
  background: white;
  cursor: pointer;
  font-size: 14px;
  font-weight: 500;
  color: var(--text-primary);
  transition: all var(--transition-base);
}

.option-button:hover {
  border-color: var(--primary-light);
  background: rgba(37, 99, 235, 0.05);
}

.option-button.selected {
  border-color: var(--primary-color);
  background: rgba(37, 99, 235, 0.1);
  font-weight: 600;
  color: var(--primary-dark);
}

.option-button.correct {
  border-color: var(--success-color);
  background: rgba(5, 150, 105, 0.1);
  color: #047857;
  font-weight: 600;
}

.option-button.incorrect {
  border-color: var(--danger-color);
  background: rgba(220, 38, 38, 0.1);
  color: #991b1b;
  font-weight: 600;
}

.explanation {
  font-size: 13px;
  color: var(--text-secondary);
  margin-top: var(--spacing-md);
  padding: var(--spacing-md);
  background: var(--gray-100);
  border-radius: var(--border-radius-sm);
  border-left: 3px solid var(--primary-color);
}

/* ============================================================
   MCQ SECTION
   ============================================================ */

.mcq-container {
  display: flex;
  flex-direction: column;
  gap: var(--spacing-lg);
}

.mcq-option {
  padding: var(--spacing-md) var(--spacing-lg);
  border-radius: var(--border-radius-md);
  text-align: left;
  border: 2px solid var(--gray-200);
  background: white;
  cursor: pointer;
  font-size: 14px;
  font-weight: 500;
  color: var(--text-primary);
  transition: all var(--transition-base);
}

.mcq-option:hover {
  border-color: var(--primary-light);
  background: rgba(37, 99, 235, 0.05);
}

.mcq-option.selected {
  border-color: var(--primary-color);
  background: rgba(37, 99, 235, 0.1);
  font-weight: 600;
  color: var(--primary-dark);
}

.mcq-option.correct {
  border-color: var(--success-color);
  background: rgba(5, 150, 105, 0.1);
  color: #047857;
  font-weight: 600;
}

.mcq-option.incorrect {
  border-color: var(--danger-color);
  background: rgba(220, 38, 38, 0.1);
  color: #991b1b;
  font-weight: 600;
}

/* ============================================================
   FILL-IN SECTION
   ============================================================ */

.fillin-container {
  display: flex;
  gap: var(--spacing-md);
  align-items: center;
  flex-wrap: wrap;
  margin-bottom: var(--spacing-md);
}

.fillin-input {
  padding: var(--spacing-sm) var(--spacing-md);
  border-radius: var(--border-radius-sm);
  border: 2px solid var(--gray-200);
  font-size: 14px;
  flex: 1;
  min-width: 140px;
  outline: none;
  transition: all var(--transition-base);
}

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

.fillin-input.correct {
  border-color: var(--success-color);
  background: rgba(5, 150, 105, 0.05);
}

.fillin-input.incorrect {
  border-color: var(--danger-color);
  background: rgba(220, 38, 38, 0.05);
}

.hint-button {
  padding: var(--spacing-sm) var(--spacing-md);
  border-radius: var(--border-radius-sm);
  border: 1px solid var(--gray-300);
  background: var(--gray-100);
  cursor: pointer;
  font-size: 12px;
  font-weight: 600;
  color: var(--text-secondary);
  transition: all var(--transition-base);
}

.hint-button:hover {
  background: white;
  border-color: var(--primary-light);
  color: var(--primary-color);
}

.hint-text {
  font-size: 13px;
  color: var(--text-secondary);
  margin-top: var(--spacing-md);
  padding: var(--spacing-md);
  background: var(--gray-100);
  border-radius: var(--border-radius-sm);
  border-left: 3px solid var(--warning-color);
}

.answer-text {
  font-size: 13px;
  color: var(--danger-color);
  margin-top: var(--spacing-md);
  padding: var(--spacing-md);
  background: rgba(220, 38, 38, 0.05);
  border-radius: var(--border-radius-sm);
  border-left: 3px solid var(--danger-color);
  font-weight: 600;
}

/* ============================================================
   MATCHING SECTION
   ============================================================ */

.matching-info {
  font-size: 13px;
  color: var(--text-secondary);
  margin-bottom: var(--spacing-lg);
  padding: var(--spacing-md) var(--spacing-lg);
  background: var(--gray-100);
  border-radius: var(--border-radius-md);
  border-left: 3px solid var(--primary-color);
  font-weight: 500;
}

.matching-grid {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: var(--spacing-lg);
  margin-bottom: var(--spacing-2xl);
}

@media (max-width: 640px) {
  .matching-grid {
    grid-template-columns: 1fr;
  }
}

.matching-column {
  display: flex;
  flex-direction: column;
  gap: var(--spacing-md);
}

.matching-column::before {
  content: attr(data-label);
  font-size: 12px;
  font-weight: 700;
  color: var(--text-secondary);
  text-transform: uppercase;
  letter-spacing: 0.5px;
  margin-bottom: var(--spacing-sm);
  padding: 0 var(--spacing-md);
}

.match-button {
  padding: var(--spacing-md) var(--spacing-lg);
  border-radius: var(--border-radius-md);
  text-align: left;
  font-size: 14px;
  font-weight: 500;
  cursor: pointer;
  border: 2px solid var(--gray-200);
  background: white;
  color: var(--text-primary);
  transition: all var(--transition-base);
}

.match-button:hover {
  border-color: var(--primary-light);
  background: rgba(37, 99, 235, 0.05);
}

.match-button.selected {
  border-color: var(--primary-color);
  background: rgba(37, 99, 235, 0.1);
  font-weight: 600;
  box-shadow: inset 0 0 0 1px var(--primary-color);
}

.match-button.matched {
  border-color: #a78bfa;
  background: rgba(167, 139, 250, 0.1);
  font-weight: 600;
}

.match-button.correct {
  border-color: var(--success-color);
  background: rgba(5, 150, 105, 0.1);
  color: #047857;
  font-weight: 600;
}

.match-button.incorrect {
  border-color: var(--danger-color);
  background: rgba(220, 38, 38, 0.1);
  color: #991b1b;
  font-weight: 600;
}

/* ============================================================
   SCORE DISPLAY
   ============================================================ */

.score-display {
  padding: var(--spacing-lg) var(--spacing-xl);
  border-radius: var(--border-radius-md);
  margin-bottom: var(--spacing-2xl);
  font-weight: 700;
  text-align: center;
  font-size: 16px;
  animation: slideIn var(--transition-base) ease-out;
}

.score-display.perfect {
  background: rgba(5, 150, 105, 0.15);
  color: #047857;
  border-left: 4px solid var(--success-color);
}

.score-display.partial {
  background: rgba(245, 158, 11, 0.15);
  color: #92400e;
  border-left: 4px solid var(--warning-color);
}

/* ============================================================
   BUTTON GROUPS
   ============================================================ */

.button-group {
  text-align: center;
  margin-top: var(--spacing-2xl);
  display: flex;
  gap: var(--spacing-md);
  justify-content: center;
  flex-wrap: wrap;
}

/* ============================================================
   RESPONSIVE DESIGN
   ============================================================ */

@media (max-width: 768px) {
  #root {
    padding: var(--spacing-sm);
  }

  .home-screen {
    padding: var(--spacing-2xl) var(--spacing-lg);
  }

  .home-header h1 {
    font-size: 32px;
  }

  .module-card {
    padding: var(--spacing-lg);
    min-height: 220px;
    gap: var(--spacing-md);
  }

  .module-card-icon {
    font-size: 42px;
  }

  .module-card-title {
    font-size: clamp(13px, 2.8vw, 15px);
  }

  .module-header {
    padding: var(--spacing-xl) var(--spacing-lg);
  }

  .module-header-top button {
    font-size: 12px;
    padding: var(--spacing-sm) var(--spacing-md);
  }

  .content-wrapper {
    padding: var(--spacing-xl) var(--spacing-lg);
  }

  .section-tabs {
    padding: 0 var(--spacing-lg);
  }

  .tabs-container {
    gap: var(--spacing-xs);
  }

  .tab-button {
    padding: var(--spacing-md) var(--spacing-md);
    font-size: 12px;
  }

  .flashcard {
    min-height: 200px;
    padding: var(--spacing-2xl) var(--spacing-lg);
  }

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

  .btn {
    width: 100%;
  }

  .matching-grid {
    gap: var(--spacing-md);
  }

  .modules-grid {
    gap: var(--spacing-md);
  }
}

@media (max-width: 480px) {
  .home-screen {
    padding: var(--spacing-xl) var(--spacing-md);
  }

  .home-header h1 {
    font-size: 24px;
  }

  .home-header p {
    font-size: 14px;
  }

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

  .module-card {
    padding: var(--spacing-md);
    min-height: 180px;
    gap: var(--spacing-sm);
  }

  .module-card-icon {
    font-size: 36px;
  }

  .module-card-title {
    font-size: 13px;
  }

  .module-card-count {
    font-size: 12px;
  }

  .module-header {
    padding: var(--spacing-lg) var(--spacing-md);
  }

  .module-header-top {
    flex-direction: row;
    gap: var(--spacing-md);
    justify-content: space-between;
    min-height: auto;
  }

  .module-header-top button {
    flex: 0 1 auto;
    max-width: 110px;
    padding: var(--spacing-sm) var(--spacing-md);
    font-size: 12px;
    min-height: 32px;
    white-space: nowrap;
  }

  .module-header h2 {
    font-size: 20px;
  }

  .content-wrapper {
    padding: var(--spacing-lg) var(--spacing-md);
  }

  .section-title {
    font-size: 18px;
  }

  .item-container {
    padding: var(--spacing-md);
    margin-bottom: var(--spacing-md);
  }

  .option-button {
    padding: var(--spacing-md);
    font-size: 13px;
  }

  .flashcard {
    min-height: 180px;
    padding: var(--spacing-2xl) var(--spacing-md);
    font-size: 16px;
  }

  .flashcard-progress {
    font-size: 12px;
    padding: var(--spacing-md);
  }

  .button-group {
    gap: var(--spacing-xs);
    flex-direction: column;
  }

  .btn {
    padding: var(--spacing-sm) var(--spacing-lg);
    font-size: 13px;
    width: 100%;
    min-height: 40px;
  }

  .fillin-container {
    flex-direction: column;
  }

  .fillin-input {
    width: 100%;
  }

  .hint-button {
    width: 100%;
  }

  .section-tabs {
    padding: 0 var(--spacing-md);
  }

  .tab-button {
    padding: var(--spacing-md) var(--spacing-sm);
    font-size: 11px;
  }
}

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

@media print {
  body {
    background: white;
  }

  #root {
    box-shadow: none;
  }

  .module-wrapper {
    box-shadow: none;
    border-radius: 0;
  }

  button {
    display: none;
  }
}

/* ============================================================
   DARK MODE SUPPORT (EXPERIMENTAL)
   ============================================================ */

@media (prefers-color-scheme: dark) {
  /* This can be expanded for dark mode if needed in the future */
}

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

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

/* Focus visible for keyboard navigation */
button:focus-visible,
input:focus-visible {
  outline: 2px solid var(--primary-color);
  outline-offset: 2px;
}