:root {
  --bg: #F0FFF4;
  --text: #1A202C;
  --primary: #38A169;
  --secondary: #2C5282;
  --accent: #ECC94B;
  --card-front: #FFFFFF;
  --card-back: #EDF2F7;
  --light-gray: #E2E8F0;
  --medium-gray: #A0AEC0;
  --error: #E53E3E;
  --success: #38A169;
  --info: #3182CE;
  --warning: #DD6B20;
  --border-radius: 8px;
  --box-shadow: 0 4px 6px rgba(0, 0, 0, 0.1);
  --transition: all 0.3s ease;
}

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

body {
  background-color: var(--bg);
  color: var(--text);
  font-family: 'Inter', -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, sans-serif;
  line-height: 1.6;
  min-height: 100vh;
}

a {
  color: var(--primary);
  text-decoration: none;
  transition: var(--transition);
}

a:hover {
  color: var(--secondary);
}

/* Container */
.container {
  width: 100%;
  max-width: 1200px;
  margin: 0 auto;
  padding: 0 20px;
}

/* Header */
header {
  background-color: white;
  box-shadow: var(--box-shadow);
  padding: 1rem 0;
  position: sticky;
  top: 0;
  z-index: 100;
}

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

.logo {
  font-weight: 700;
  font-size: 1.5rem;
  color: var(--primary);
}

.nav-links {
  display: flex;
  gap: 1.5rem;
}

.nav-links a {
  color: var(--text);
  font-weight: 500;
}

.nav-links a:hover,
.nav-links a.active {
  color: var(--primary);
}

/* Auth Forms */
.auth-container {
  max-width: 400px;
  margin: 3rem auto;
  background: white;
  padding: 2rem;
  border-radius: var(--border-radius);
  box-shadow: var(--box-shadow);
}

.form-group {
  margin-bottom: 1.5rem;
}

.form-group label {
  display: block;
  margin-bottom: 0.5rem;
  font-weight: 500;
}

.form-control {
  width: 100%;
  padding: 0.75rem;
  font-size: 1rem;
  border: 1px solid var(--light-gray);
  border-radius: var(--border-radius);
  transition: var(--transition);
}

.form-control:focus {
  outline: none;
  border-color: var(--primary);
  box-shadow: 0 0 0 3px rgba(56, 161, 105, 0.2);
}

/* Buttons */
.btn {
  display: inline-block;
  padding: 0.75rem 1.5rem;
  font-size: 1rem;
  font-weight: 500;
  text-align: center;
  border: none;
  border-radius: var(--border-radius);
  cursor: pointer;
  transition: var(--transition);
}

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

.btn-primary:hover {
  background-color: #2F855A;
}

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

.btn-secondary:hover {
  background-color: #1A365D;
}

.btn-accent {
  background-color: var(--accent);
  color: var(--text);
}

.btn-accent:hover {
  background-color: #D69E2E;
}

.btn-outline {
  background-color: transparent;
  border: 1px solid var(--primary);
  color: var(--primary);
}

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

.btn-block {
  display: block;
  width: 100%;
}

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

/* Cards */
.card {
  background: white;
  border-radius: var(--border-radius);
  box-shadow: var(--box-shadow);
  margin-bottom: 1.5rem;
  overflow: hidden;
  transition: var(--transition);
}

.card:hover {
  transform: translateY(-5px);
  box-shadow: 0 10px 15px rgba(0, 0, 0, 0.1);
}

.card-header {
  padding: 1.5rem;
  border-bottom: 1px solid var(--light-gray);
}

.card-body {
  padding: 1.5rem;
}

.card-footer {
  padding: 1rem 1.5rem;
  border-top: 1px solid var(--light-gray);
  display: flex;
  justify-content: space-between;
  align-items: center;
}

/* Dashboard */
.dashboard {
  padding: 2rem 0;
}

.dashboard-header {
  margin-bottom: 2rem;
}

.stats-container {
  display: grid;
  grid-template-columns: repeat(auto-fill, minmax(250px, 1fr));
  gap: 1.5rem;
  margin-bottom: 2rem;
}

.stat-card {
  background: white;
  padding: 1.5rem;
  border-radius: var(--border-radius);
  box-shadow: var(--box-shadow);
}

.stat-card h3 {
  font-size: 1rem;
  color: var(--medium-gray);
  margin-bottom: 0.5rem;
}

.stat-card .stat-value {
  font-size: 2rem;
  font-weight: 700;
  color: var(--primary);
}

/* Module Cards */
.module-cards {
  display: grid;
  grid-template-columns: repeat(auto-fill, minmax(300px, 1fr));
  gap: 1.5rem;
}

.module-card {
  background: white;
  border-radius: var(--border-radius);
  box-shadow: var(--box-shadow);
  padding: 1.5rem;
  transition: var(--transition);
}

.module-card:hover {
  transform: translateY(-5px);
  box-shadow: 0 10px 15px rgba(0, 0, 0, 0.1);
}

.module-card h3 {
  margin-bottom: 0.5rem;
  font-size: 1.25rem;
}

.module-card p {
  color: var(--medium-gray);
  margin-bottom: 1rem;
}

.module-card .deck-count {
  display: inline-block;
  background: var(--light-gray);
  padding: 0.25rem 0.75rem;
  border-radius: 20px;
  font-size: 0.875rem;
  font-weight: 500;
}

/* Deck List */
.deck-list {
  margin-top: 2rem;
}

.deck-item {
  display: flex;
  justify-content: space-between;
  align-items: center;
  padding: 1rem;
  background: white;
  border-radius: var(--border-radius);
  margin-bottom: 0.75rem;
  box-shadow: var(--box-shadow);
  transition: var(--transition);
}

.deck-item:hover {
  transform: translateY(-2px);
  box-shadow: 0 6px 8px rgba(0, 0, 0, 0.1);
}

.deck-info h3 {
  font-size: 1.125rem;
  margin-bottom: 0.25rem;
}

.deck-meta {
  display: flex;
  gap: 1rem;
  font-size: 0.875rem;
  color: var(--medium-gray);
}

.deck-actions {
  display: flex;
  gap: 0.5rem;
}

/* Flash Card */
.study-container {
  max-width: 700px;
  margin: 2rem auto;
}

.study-header {
  display: flex;
  justify-content: space-between;
  align-items: center;
  margin-bottom: 1.5rem;
}

.study-progress {
  height: 8px;
  width: 100%;
  background-color: var(--light-gray);
  border-radius: 4px;
  margin-bottom: 2rem;
  overflow: hidden;
}

.progress-bar {
  height: 100%;
  background-color: var(--primary);
  transition: width 0.3s ease;
}

.study-card-container {
  perspective: 1000px;
  height: 400px;
  margin-bottom: 1.5rem;
}

.study-card {
  position: relative;
  width: 100%;
  height: 100%;
  transform-style: preserve-3d;
  transition: transform 0.8s;
}

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

.study-card-side {
  position: absolute;
  width: 100%;
  height: 100%;
  backface-visibility: hidden;
  border-radius: var(--border-radius);
  box-shadow: var(--box-shadow);
  padding: 2rem;
  display: flex;
  flex-direction: column;
  justify-content: center;
  align-items: center;
  text-align: center;
}

.study-card-front {
  background-color: var(--card-front);
}

.study-card-back {
  background-color: var(--card-back);
  transform: rotateY(180deg);
}

.study-controls {
  display: flex;
  justify-content: center;
  gap: 1rem;
  margin-top: 2rem;
}

.quality-btn {
  padding: 0.75rem;
  min-width: 4rem;
  font-weight: 500;
  border: none;
  border-radius: var(--border-radius);
  cursor: pointer;
  transition: var(--transition);
}

.quality-btn-0 { background-color: #FC8181; }
.quality-btn-1 { background-color: #F6AD55; }
.quality-btn-2 { background-color: #F6E05E; }
.quality-btn-3 { background-color: #68D391; }
.quality-btn-4 { background-color: #4FD1C5; }
.quality-btn-5 { background-color: #4299E1; }

.quality-btn:hover {
  filter: brightness(0.9);
  transform: translateY(-2px);
}

/* Card Editor */
.card-editor {
  max-width: 700px;
  margin: 2rem auto;
  background: white;
  padding: 2rem;
  border-radius: var(--border-radius);
  box-shadow: var(--box-shadow);
}

.editor-field {
  margin-bottom: 1.5rem;
}

.editor-field label {
  display: block;
  margin-bottom: 0.5rem;
  font-weight: 500;
}

.editor-textarea {
  width: 100%;
  min-height: 150px;
  padding: 0.75rem;
  font-size: 1rem;
  border: 1px solid var(--light-gray);
  border-radius: var(--border-radius);
  transition: var(--transition);
}

.editor-textarea:focus {
  outline: none;
  border-color: var(--primary);
}

.tag-input {
  display: flex;
  flex-wrap: wrap;
  gap: 0.5rem;
  padding: 0.5rem;
  border: 1px solid var(--light-gray);
  border-radius: var(--border-radius);
}

.tag {
  background: var(--light-gray);
  padding: 0.25rem 0.5rem;
  border-radius: 4px;
  display: flex;
  align-items: center;
  gap: 0.25rem;
}

.tag .remove {
  cursor: pointer;
}

.tag-input input {
  border: none;
  flex-grow: 1;
  padding: 0.25rem;
}

.tag-input input:focus {
  outline: none;
}

/* Modal */
.modal-backdrop {
  position: fixed;
  top: 0;
  left: 0;
  right: 0;
  bottom: 0;
  background: rgba(0, 0, 0, 0.5);
  display: flex;
  align-items: center;
  justify-content: center;
  z-index: 1000;
}

.modal {
  background: white;
  border-radius: var(--border-radius);
  max-width: 500px;
  width: 100%;
  padding: 2rem;
  box-shadow: var(--box-shadow);
}

.modal-header {
  display: flex;
  justify-content: space-between;
  align-items: center;
  margin-bottom: 1.5rem;
}

.modal-close {
  background: transparent;
  border: none;
  font-size: 1.5rem;
  cursor: pointer;
  color: var(--medium-gray);
}

.modal-footer {
  margin-top: 1.5rem;
  display: flex;
  justify-content: flex-end;
  gap: 1rem;
}

/* Alerts */
.alert {
  padding: 1rem;
  margin-bottom: 1rem;
  border-radius: var(--border-radius);
}

.alert-success {
  background-color: #C6F6D5;
  color: #22543D;
}

.alert-error {
  background-color: #FED7D7;
  color: #822727;
}

.alert-info {
  background-color: #BEE3F8;
  color: #2A4365;
}

.alert-warning {
  background-color: #FEEBC8;
  color: #7B341E;
}

/* Utilities */
.text-center { text-align: center; }
.mb-1 { margin-bottom: 0.5rem; }
.mb-2 { margin-bottom: 1rem; }
.mb-3 { margin-bottom: 1.5rem; }
.mb-4 { margin-bottom: 2rem; }
.mt-1 { margin-top: 0.5rem; }
.mt-2 { margin-top: 1rem; }
.mt-3 { margin-top: 1.5rem; }
.mt-4 { margin-top: 2rem; }

/* Responsive */
@media (max-width: 768px) {
  .stats-container {
    grid-template-columns: 1fr;
  }
  
  .module-cards {
    grid-template-columns: 1fr;
  }
  
  .deck-item {
    flex-direction: column;
    align-items: flex-start;
  }
  
  .deck-actions {
    margin-top: 1rem;
    width: 100%;
    justify-content: space-between;
  }
  
  .study-controls {
    flex-wrap: wrap;
  }
}

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

.fade-in {
  animation: fadeIn 0.3s ease;
}

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

.slide-up {
  animation: slideUp 0.4s ease;
}

/* Study interface styles */
.flashcard {
  perspective: 1000px;
  width: 100%;
  max-width: 600px;
  height: 300px;
  margin: 0 auto;
  position: relative;
}

.flashcard-inner {
  position: relative;
  width: 100%;
  height: 100%;
  text-align: center;
  transition: transform 0.6s;
  transform-style: preserve-3d;
}

.flashcard.flipped .flashcard-inner {
  transform: rotateY(180deg);
}

.flashcard-front, .flashcard-back {
  position: absolute;
  width: 100%;
  height: 100%;
  -webkit-backface-visibility: hidden;
  backface-visibility: hidden;
  display: flex;
  align-items: center;
  justify-content: center;
  padding: 20px;
  border-radius: 10px;
  box-shadow: 0 4px 8px rgba(0,0,0,0.1);
}

.flashcard-front {
  background-color: #ffffff;
  color: #333;
}

.flashcard-back {
  background-color: #f8f9fa;
  color: #333;
  transform: rotateY(180deg);
}

.card-content {
  font-size: 1.4rem;
  overflow-y: auto;
  max-height: 250px;
  width: 100%;
  word-break: break-word;
}

.rating-buttons {
  margin-top: 30px;
  display: none;
  justify-content: center;
  gap: 10px;
  flex-wrap: wrap;
}

.rating-button {
  padding: 10px 15px;
  border: none;
  border-radius: 5px;
  cursor: pointer;
  font-weight: 500;
  transition: all 0.2s;
}

.rating-button:hover {
  filter: brightness(1.1);
}

.rating-0 { background-color: #e53e3e; color: white; }
.rating-1 { background-color: #ed8936; color: white; }
.rating-2 { background-color: #ecc94b; color: black; }
.rating-3 { background-color: #48bb78; color: white; }
.rating-4 { background-color: #38a169; color: white; }
.rating-5 { background-color: #2b6cb0; color: white; }

.study-controls {
  margin-top: 20px;
  display: flex;
  justify-content: center;
  gap: 15px;
}

.study-progress {
  margin-top: 20px;
  text-align: center;
}

.progress-bar {
  width: 100%;
  background-color: #e2e8f0;
  border-radius: 5px;
  height: 10px;
  margin-top: 10px;
  overflow: hidden;
}

.progress-fill {
  height: 100%;
  background-color: #4299e1;
  width: 0%;
  transition: width 0.3s ease;
}

.completion-message {
  text-align: center;
  padding: 60px 20px;
  background-color: #f9f9f9;
  border-radius: 10px;
  margin-top: 30px;
}

/* Modern Study Interface Styles */
:root {
  --primary: #4CAF50;
  --secondary: #4299e1;
  --success: #38a169;
  --danger: #e53e3e;
  --warning: #ed8936;
  --info: #2b6cb0;
  --background: #f0f7f1;
  --card-front: #ffffff;
  --card-back: #f8f9fa;
  --text: #333333;
  --text-light: #666666;
  --shadow-sm: 0 2px 5px rgba(0,0,0,0.08);
  --shadow-md: 0 4px 10px rgba(0,0,0,0.1);
  --shadow-lg: 0 10px 25px rgba(0,0,0,0.12);
  --transition-speed: 0.3s;
  --border-radius: 12px;
}

body {
  background-color: var(--background);
  font-family: 'Inter', sans-serif;
  margin: 0;
  padding: 0;
  min-height: 100vh;
  display: flex;
  flex-direction: column;
}

/* Modern Header */
.modern-header {
  background-color: #fff;
  box-shadow: var(--shadow-sm);
  position: sticky;
  top: 0;
  z-index: 10;
  padding: 15px 0;
}

.modern-header .container {
  display: flex;
  justify-content: space-between;
  align-items: center;
  max-width: 1200px;
  margin: 0 auto;
  padding: 0 20px;
}

.logo {
  font-size: 24px;
  font-weight: 700;
  color: var(--primary);
  text-decoration: none;
}

.nav-links {
  display: flex;
  gap: 20px;
}

.nav-links a {
  color: var(--text);
  text-decoration: none;
  font-weight: 500;
  padding: 8px 12px;
  border-radius: 6px;
  transition: all var(--transition-speed);
  display: flex;
  align-items: center;
  gap: 6px;
}

.nav-links a:hover {
  background-color: rgba(76, 175, 80, 0.1);
  color: var(--primary);
}

/* Main Content Area */
.modern-main {
  flex: 1;
  padding: 40px 0;
}

.study-wrapper {
  max-width: 1000px;
  margin: 0 auto;
  padding: 0 20px;
}

.study-header {
  display: flex;
  justify-content: space-between;
  align-items: flex-start;
  margin-bottom: 30px;
}

.study-title-group h1 {
  font-size: 32px;
  color: var(--text);
  margin: 0 0 10px 0;
  font-weight: 600;
}

.deck-description {
  color: var(--text-light);
  margin: 0;
  font-size: 16px;
  max-width: 600px;
}

.back-button {
  display: flex;
  align-items: center;
  gap: 8px;
  background-color: transparent;
  color: var(--primary);
  border: 2px solid var(--primary);
  border-radius: var(--border-radius);
  padding: 10px 16px;
  font-weight: 600;
  text-decoration: none;
  transition: all var(--transition-speed);
}

.back-button:hover {
  background-color: var(--primary);
  color: white;
}

/* Study Container */
.study-container {
  position: relative;
}

/* Loading Indicator */
.loading-indicator {
  display: flex;
  flex-direction: column;
  align-items: center;
  justify-content: center;
  height: 300px;
}

.spinner {
  width: 40px;
  height: 40px;
  border: 4px solid rgba(76, 175, 80, 0.2);
  border-radius: 50%;
  border-top-color: var(--primary);
  animation: spin 1s linear infinite;
  margin-bottom: 15px;
}

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

/* Modern Flashcard */
.flashcard-container {
  perspective: 2000px;
  margin: 20px auto;
  max-width: 700px;
}

.flashcard {
  width: 100%;
  height: 400px;
  position: relative;
  transform-style: preserve-3d;
  transition: transform 0.8s cubic-bezier(0.175, 0.885, 0.32, 1.275);
  border-radius: var(--border-radius);
  box-shadow: var(--shadow-lg);
}

.flashcard.flipped {
  transform: rotateY(180deg);
}

.flashcard-side {
  position: absolute;
  width: 100%;
  height: 100%;
  backface-visibility: hidden;
  border-radius: var(--border-radius);
  display: flex;
  align-items: center;
  justify-content: center;
  padding: 30px;
  box-sizing: border-box;
}

.flashcard-front {
  background-color: var(--card-front);
  color: var(--text);
  box-shadow: inset 0 0 0 1px rgba(0,0,0,0.1);
}

.flashcard-back {
  background-color: var(--card-back);
  color: var(--text);
  transform: rotateY(180deg);
  box-shadow: inset 0 0 0 1px rgba(0,0,0,0.1);
}

.card-content {
  font-size: 1.5rem;
  line-height: 1.5;
  text-align: center;
  max-height: 320px;
  overflow-y: auto;
  width: 100%;
  padding: 0 10px;
}

/* Study Progress */
.study-progress {
  margin: 30px auto;
  max-width: 700px;
}

.progress-indicator {
  display: flex;
  justify-content: space-between;
  margin-bottom: 10px;
  font-weight: 500;
}

.progress-bar {
  height: 8px;
  background-color: rgba(76, 175, 80, 0.2);
  border-radius: 4px;
  overflow: hidden;
}

.progress-fill {
  height: 100%;
  background-color: var(--primary);
  transition: width 0.3s ease;
  width: 0%;
}

/* Controls */
.card-controls {
  display: flex;
  flex-direction: column;
  align-items: center;
  margin-top: 30px;
}

.primary-controls {
  margin-bottom: 20px;
}

.show-answer-btn {
  background-color: var(--primary);
  color: white;
  border: none;
  border-radius: var(--border-radius);
  padding: 14px 24px;
  font-size: 16px;
  font-weight: 600;
  cursor: pointer;
  transition: all var(--transition-speed);
  box-shadow: var(--shadow-sm);
  display: flex;
  align-items: center;
  gap: 8px;
}

.show-answer-btn:hover {
  background-color: #43a047;
  transform: translateY(-2px);
  box-shadow: var(--shadow-md);
}

.next-card-btn {
  background-color: var(--info);
  color: white;
  border: none;
  border-radius: var(--border-radius);
  padding: 14px 24px;
  font-size: 16px;
  font-weight: 600;
  cursor: pointer;
  transition: all var(--transition-speed);
  box-shadow: var(--shadow-sm);
  display: flex;
  align-items: center;
  gap: 8px;
}

.next-card-btn:hover {
  background-color: #2563a7;
  transform: translateY(-2px);
  box-shadow: var(--shadow-md);
}

/* Rating Buttons */
.rating-buttons {
  display: flex;
  flex-wrap: wrap;
  justify-content: center;
  gap: 12px;
  max-width: 700px;
  margin: 0 auto;
}

.rating-button {
  background-color: #f1f1f1;
  color: var(--text);
  border: none;
  border-radius: var(--border-radius);
  padding: 12px 18px;
  font-size: 15px;
  font-weight: 500;
  cursor: pointer;
  transition: all var(--transition-speed);
  min-width: 80px;
  display: flex;
  flex-direction: column;
  align-items: center;
  gap: 5px;
}

.rating-button:hover {
  transform: translateY(-3px);
  box-shadow: var(--shadow-sm);
}

.rating-button i {
  font-size: 18px;
}

.rating-0 { background-color: var(--danger); color: white; }
.rating-1 { background-color: var(--warning); color: white; }
.rating-2 { background-color: #f6e05e; color: #744210; }
.rating-3 { background-color: #68d391; color: #22543d; }
.rating-4 { background-color: var(--success); color: white; }
.rating-5 { background-color: var(--info); color: white; }

.rating-0:hover { background-color: #c53030; }
.rating-1:hover { background-color: #dd6b20; }
.rating-2:hover { background-color: #ecc94b; }
.rating-3:hover { background-color: #48bb78; }
.rating-4:hover { background-color: #2f855a; }
.rating-5:hover { background-color: #2c5282; }

/* Completion Message */
.completion-message {
  text-align: center;
  background-color: white;
  padding: 40px;
  border-radius: var(--border-radius);
  box-shadow: var(--shadow-md);
  max-width: 700px;
  margin: 40px auto;
}

.completion-message h2 {
  font-size: 28px;
  color: var(--primary);
  margin-top: 0;
}

.completion-icon {
  font-size: 60px;
  color: var(--primary);
  margin-bottom: 20px;
}

.completion-message .button-group {
  margin-top: 30px;
  display: flex;
  justify-content: center;
  gap: 15px;
}

/* Footer */
.modern-footer {
  background-color: white;
  padding: 20px 0;
  text-align: center;
  font-size: 14px;
  color: var(--text-light);
  margin-top: auto;
  box-shadow: 0 -2px 10px rgba(0,0,0,0.03);
}

/* Responsive Design */
@media (max-width: 768px) {
  .study-header {
    flex-direction: column;
    gap: 20px;
  }
  
  .back-button {
    align-self: flex-start;
  }
  
  .flashcard {
    height: 300px;
  }
  
  .card-content {
    font-size: 1.3rem;
    max-height: 220px;
  }
  
  .rating-buttons {
    gap: 8px;
  }
  
  .rating-button {
    padding: 10px 12px;
    min-width: 70px;
    font-size: 14px;
  }
}

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

.slide-up {
  animation: slideUp 0.5s ease-out;
}

.pulse {
  animation: pulse 1.5s infinite;
}

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

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

@keyframes pulse {
  0% { transform: scale(1); }
  50% { transform: scale(1.05); }
  100% { transform: scale(1); }
}

/* Add these styles to your study.css file */

/* Rating button states */
.rating-button.selected {
  transform: scale(1.05);
  box-shadow: 0 0 0 2px var(--primary-color);
}

.rating-button.disabled {
  opacity: 0.7;
  cursor: not-allowed;
}

.rating-buttons.loading {
  opacity: 0.8;
  position: relative;
}

.rating-buttons.loading::after {
  content: '';
  position: absolute;
  top: 50%;
  left: 50%;
  transform: translate(-50%, -50%);
  width: 30px;
  height: 30px;
  border: 3px solid rgba(56, 161, 105, 0.3);
  border-top: 3px solid var(--primary-color);
  border-radius: 50%;
  animation: spin 1s linear infinite;
}

/* Toast notifications */
.toast {
  position: fixed;
  bottom: 30px;
  left: 50%;
  transform: translateX(-50%);
  padding: 12px 24px;
  border-radius: 8px;
  color: white;
  font-weight: 500;
  opacity: 0;
  transition: opacity 0.3s ease-in-out;
  z-index: 1000;
  pointer-events: none;
}

.toast-success {
  background-color: var(--primary-color);
  box-shadow: 0 4px 15px rgba(56, 161, 105, 0.3);
}

.toast-error {
  background-color: #E53E3E;
  box-shadow: 0 4px 15px rgba(229, 62, 62, 0.3);
}

.toast-info {
  background-color: #3182CE;
  box-shadow: 0 4px 15px rgba(49, 130, 206, 0.3);
}

.show-toast {
  opacity: 1;
}

/* Study stats */
.study-stats {
  display: flex;
  justify-content: center;
  gap: 2rem;
  margin-top: 1.5rem;
  padding: 0.5rem;
  background-color: #f8f9fa;
  border-radius: 8px;
}

.stat-item {
  display: flex;
  align-items: center;
  gap: 0.5rem;
  color: #4a5568;
  font-size: 0.95rem;
}

.stat-item i {
  color: var(--primary-color);
}

/* Animation */
.pulse {
  animation: pulse 0.4s ease-in-out;
}

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

/* Stats summary */
.stats-summary {
  display: flex;
  justify-content: center;
  gap: 2rem;
  margin: 1.5rem 0;
}

.summary-item {
  display: flex;
  flex-direction: column;
  align-items: center;
  background-color: rgba(56, 161, 105, 0.1);
  padding: 1rem;
  border-radius: 8px;
  min-width: 120px;
}

.summary-label {
  font-size: 0.9rem;
  color: #4a5568;
  margin-bottom: 0.25rem;
}

.summary-value {
  font-size: 2rem;
  font-weight: 700;
  color: var(--primary-color);
}

/* Study more options */
.study-options {
  margin-top: 1.5rem;
  text-align: center;
}

.options-label {
  font-size: 1rem;
  color: #718096;
  margin-bottom: 1rem;
}

.button-group {
  display: flex;
  flex-wrap: wrap;
  justify-content: center;
  gap: 1rem;
  margin-top: 1.5rem;
}

/* Special tag for non-due cards */
.card-tag {
  position: absolute;
  top: 0;
  right: 0;
  background-color: rgba(66, 153, 225, 0.8);
  color: white;
  padding: 0.25rem 0.5rem;
  border-radius: 0 var(--border-radius) 0 var(--border-radius);
  font-size: 0.75rem;
  font-weight: 600;
}

.card-tag.due {
  background-color: rgba(56, 161, 105, 0.8);
}

.card-tag.new {
  background-color: rgba(236, 201, 75, 0.8);
}

/* Card tag for bonus study */
.card-tag {
  position: absolute;
  top: 10px;
  right: 10px;
  padding: 0.3rem 0.6rem;
  border-radius: 4px;
  font-size: 0.8rem;
  font-weight: 600;
  z-index: 10;
  background-color: #3182ce;
  color: white;
  box-shadow: 0 2px 5px rgba(0,0,0,0.1);
}

/* Rating button improvements */
.rating-button {
  position: relative;
  overflow: hidden;
  cursor: pointer;
  transition: transform 0.2s, box-shadow 0.2s;
}

.rating-button:hover {
  transform: translateY(-3px);
  box-shadow: 0 4px 8px rgba(0,0,0,0.1);
}

.rating-button:active {
  transform: translateY(-1px);
}

.rating-button.selected {
  transform: scale(1.05);
  box-shadow: 0 0 0 2px var(--primary-color);
}

.rating-button.disabled,
.rating-button:disabled {
  opacity: 0.6;
  cursor: not-allowed;
  transform: none !important;
  box-shadow: none !important;
}

/* Loading state for buttons */
.rating-buttons.loading {
  opacity: 0.8;
  position: relative;
}

.rating-buttons.loading::after {
  content: '';
  position: absolute;
  top: 50%;
  left: 50%;
  transform: translate(-50%, -50%);
  width: 30px;
  height: 30px;
  border: 3px solid rgba(56, 161, 105, 0.3);
  border-top: 3px solid var(--primary-color);
  border-radius: 50%;
  animation: spin 1s linear infinite;
}

@keyframes spin {
  0% { transform: translate(-50%, -50%) rotate(0deg); }
  100% { transform: translate(-50%, -50%) rotate(360deg); }
}

/* Animation for button feedback */
.pulse {
  animation: pulse 0.4s ease-in-out;
}

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

/* Toast notifications */
.toast {
  position: fixed;
  bottom: 30px;
  left: 50%;
  transform: translateX(-50%);
  padding: 12px 24px;
  border-radius: 8px;
  color: white;
  font-weight: 500;
  opacity: 0;
  transition: opacity 0.3s ease-in-out;
  z-index: 1000;
  box-shadow: 0 4px 15px rgba(0,0,0,0.2);
}

.toast-success {
  background-color: var(--primary-color);
}

.toast-error {
  background-color: #e53e3e;
}

.toast-info {
  background-color: #3182ce;
}

.show-toast {
  opacity: 1;
}

/* Bonus study tag */
.card-tag {
  position: absolute;
  top: 10px;
  right: 10px;
  padding: 0.3rem 0.6rem;
  border-radius: 4px;
  font-size: 0.8rem;
  font-weight: 600;
  z-index: 10;
  background-color: #3182ce;
  color: white;
}

/* Loading state for buttons */
.rating-buttons.loading {
  opacity: 0.8;
  position: relative;
}

.rating-buttons.loading::after {
  content: '';
  position: absolute;
  top: 50%;
  left: 50%;
  transform: translate(-50%, -50%);
  width: 30px;
  height: 30px;
  border: 3px solid rgba(56, 161, 105, 0.3);
  border-top: 3px solid var(--primary-color);
  border-radius: 50%;
  animation: spin 1s linear infinite;
}