:root {
  --primary-color: #7c4dff;
  --primary-dark: #5e35b1;
  --secondary-color: #1e88e5;
  --correct-color: #43a047;
  --wrong-color: #e53935;
  --dark-bg: #121212;
  --dark-surface: #1e1e1e;
  --dark-card: #252525;
  --dark-hover: #2c2c2c;
  --light-text: #f5f5f5;
  --gray-text: #aaaaaa;
  --border-radius: 8px;
  --card-shadow: 0 4px 6px rgba(0, 0, 0, 0.3);
  --transition: all 0.3s ease;
}

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

body {
  font-family: 'Segoe UI', Tahoma, Geneva, Verdana, sans-serif;
  background-color: var(--dark-bg);
  color: var(--light-text);
  line-height: 1.6;
}

.container {
  max-width: 900px;
  margin: 0 auto;
  padding: 20px;
}

header {
  text-align: center;
  margin-bottom: 30px;
  padding-bottom: 15px;
  border-bottom: 1px solid rgba(255, 255, 255, 0.1);
}

h1 {
  color: var(--light-text);
  font-size: 2.2rem;
}

h1 i, h2 i {
  margin-right: 10px;
  color: var(--primary-color);
}

h2 {
  margin-bottom: 20px;
  font-size: 1.8rem;
  color: var(--light-text);
}

.hidden {
  display: none !important;
}

/* Tabs */
.tabs {
  display: flex;
  margin-bottom: 20px;
  background-color: var(--dark-surface);
  border-radius: var(--border-radius);
  overflow: hidden;
}

.tab {
  flex: 1;
  padding: 15px;
  text-align: center;
  cursor: pointer;
  transition: var(--transition);
  font-weight: 500;
}

.tab:hover {
  background-color: var(--dark-hover);
}

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

.tab-content {
  display: none;
  animation: fadeIn 0.5s ease;
}

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

/* Upload Section */
.upload-card {
  background-color: var(--dark-card);
  border-radius: var(--border-radius);
  padding: 25px;
  box-shadow: var(--card-shadow);
}

.form-group {
  margin-bottom: 20px;
}

.form-group label {
  display: block;
  margin-bottom: 8px;
  font-weight: 500;
  color: var(--gray-text);
}

.form-group.checkbox {
  display: flex;
  align-items: center;
}

.form-group.checkbox label {
  margin-bottom: 0;
  margin-left: 10px;
}

input[type="text"] {
  width: 100%;
  padding: 12px 15px;
  background-color: var(--dark-surface);
  border: 1px solid rgba(255, 255, 255, 0.1);
  border-radius: var(--border-radius);
  color: var(--light-text);
  font-size: 1rem;
  transition: var(--transition);
}

input[type="text"]:focus {
  outline: none;
  border-color: var(--primary-color);
  box-shadow: 0 0 0 2px rgba(124, 77, 255, 0.2);
}

input[type="file"] {
  display: block;
  width: 100%;
  padding: 10px;
  background-color: var(--dark-surface);
  border-radius: var(--border-radius);
  border: 1px dashed rgba(255, 255, 255, 0.2);
  cursor: pointer;
  color: var(--gray-text);
}

input[type="checkbox"] {
  width: 18px;
  height: 18px;
  accent-color: var(--primary-color);
}

/* Buttons */
.btn {
  padding: 8px 12px;
  border: none;
  border-radius: var(--border-radius);
  font-weight: 600;
  cursor: pointer;
  transition: var(--transition);
  display: inline-flex;
  align-items: center;
  justify-content: center;
  font-size: 0.9rem;
  white-space: nowrap;
}

.deck-actions .btn {
  flex: 1;
  min-width: 0;
  padding: 8px;
}

.btn i {
  margin-right: 8px;
}

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

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

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

.btn.secondary:hover {
  background-color: #1976d2;
}

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

.btn.correct:hover {
  background-color: #388e3c;
}

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

.btn.wrong:hover {
  background-color: #d32f2f;
}

.btn.neutral {
  background-color: var(--dark-surface);
  color: var(--light-text);
}

.btn.neutral:hover {
  background-color: var(--dark-hover);
}

/* Deck List */
.deck-list {
  display: grid;
  grid-template-columns: repeat(auto-fill, minmax(250px, 1fr));
  gap: 20px;
}

.deck-item {
  background-color: var(--dark-card);
  border-radius: var(--border-radius);
  padding: 20px;
  box-shadow: var(--card-shadow);
  transition: var(--transition);
}

.deck-item:hover {
  transform: translateY(-5px);
  box-shadow: 0 6px 10px rgba(0, 0, 0, 0.4);
}

.deck-title {
  font-size: 1.2rem;
  margin-bottom: 15px;
  color: var(--light-text);
  display: flex;
  align-items: center;
}

.deck-title i {
  margin-right: 10px;
  color: var(--primary-color);
}

.deck-stats {
  font-size: 0.9rem;
  color: var(--gray-text);
  margin-bottom: 15px;
}

.deck-actions {
  display: flex;
  flex-wrap: wrap;
  gap: 8px;
  justify-content: space-between;
}

/* Study Section */
.study-container {
  background-color: var(--dark-card);
  border-radius: var(--border-radius);
  padding: 25px;
  box-shadow: var(--card-shadow);
}

.study-header {
  margin-bottom: 20px;
}

.progress-container {
  margin-top: 15px;
}

.progress-stats {
  display: flex;
  justify-content: space-between;
  align-items: center;
  margin-bottom: 8px;
  flex-wrap: wrap;
  gap: 10px;
}

.progress-text {
  margin-bottom: 0;
  color: var(--gray-text);
  font-size: 0.9rem;
  font-weight: 500;
}

.progress-percent {
  color: var(--primary-color);
  font-size: 0.9rem;
  font-weight: 600;
}

.accuracy-percent {
  color: var(--correct-color);
  font-size: 0.9rem;
  font-weight: 600;
}

/* Responsive adjustments */
@media (max-width: 600px) {
  .progress-stats {
    flex-direction: column;
    align-items: flex-start;
    gap: 5px;
  }
}

.progress-bar {
  height: 6px;
  background-color: var(--dark-surface);
  border-radius: 3px;
  overflow: hidden;
}

.progress-fill {
  height: 100%;
  background-color: var(--primary-color);
  width: 0%;
  transition: width 0.5s ease;
}

.study-options {
  display: flex;
  margin-bottom: 20px;
  flex-wrap: wrap;
  gap: 20px;
}

.option {
  display: flex;
  align-items: center;
}

.option label {
  margin-left: 8px;
  cursor: pointer;
}

.flashcard {
  background-color: var(--dark-surface);
  border-radius: var(--border-radius);
  box-shadow: var(--card-shadow);
  min-height: 250px;
  margin-bottom: 20px;
  transition: var(--transition);
}

.flashcard-content {
  padding: 30px;
  min-height: 200px;
}

.flashcard-question {
  margin-bottom: 20px;
}

.flashcard-answer {
  color: var(--primary-color);
}

.flashcard-answer hr {
  border: none;
  height: 1px;
  background-color: rgba(255, 255, 255, 0.1);
  margin: 15px 0;
}

.card-controls {
  display: flex;
  padding: 15px 25px;
  background-color: var(--dark-card);
  border-radius: 0 0 var(--border-radius) var(--border-radius);
  gap: 10px;
  flex-wrap: wrap;
}

.response-buttons {
  display: flex;
  gap: 10px;
  margin-left: auto;
}

/* For smaller screens */
@media (max-width: 600px) {
  .card-controls {
    flex-direction: column;
  }
  
  .response-buttons {
    margin-left: 0;
    width: 100%;
    margin-top: 10px;
    justify-content: space-between;
  }
}

/* Empty state */
.empty-state {
  text-align: center;
  padding: 60px 0;
  color: var(--gray-text);
}

.empty-state i {
  margin-bottom: 15px;
  opacity: 0.5;
}

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

.jump-option {
  display: flex;
  align-items: center;
  gap: 8px;
}

.jump-option label {
  margin: 0;
  white-space: nowrap;
  font-size: 0.9rem;
}

#jumpIndex {
  width: 60px;
  padding: 6px 8px;
  background-color: var(--dark-surface);
  border: 1px solid rgba(255, 255, 255, 0.1);
  border-radius: var(--border-radius);
  color: var(--light-text);
  font-size: 0.9rem;
  text-align: center;
}

#jumpIndex:focus {
  outline: none;
  border-color: var(--primary-color);
  box-shadow: 0 0 0 2px rgba(124, 77, 255, 0.2);
}

.jump-btn {
  padding: 6px 10px;
  font-size: 0.8rem;
}

.audio-controls {
  display: flex;
  gap: 10px;
  align-items: center;
  justify-content: flex-start;
}
.audio-controls .btn {
  padding: 0.5em 0.75em;
  font-size: 1.1em;
}