/* style.css - Premium Design System for Philosophy Review App */

@import url('https://fonts.googleapis.com/css2?family=Be+Vietnam+Pro:wght@300;400;500;600;700;800&family=Plus+Jakarta+Sans:wght@400;500;600;700;800&family=JetBrains+Mono:wght@400;500&display=swap');

:root {
  /* Light Theme Palette */
  --bg-primary: #f8fafc; /* slate-50 */
  --bg-secondary: #ffffff;
  --bg-tertiary: #f1f5f9; /* slate-100 */
  --text-primary: #0f172a; /* slate-900 */
  --text-secondary: #475569; /* slate-600 */
  --text-muted: #94a3b8; /* slate-400 */
  --border-color: #e2e8f0; /* slate-200 */
  --accent-color: #3b82f6; /* blue-500 */
  --accent-hover: #2563eb; /* blue-600 */
  --accent-light: #eff6ff; /* blue-50 */
  --success-color: #10b981; /* emerald-500 */
  --success-light: #ecfdf5; /* emerald-50 */
  --error-color: #ef4444; /* red-500 */
  --error-light: #fef2f2; /* red-50 */
  --starred-color: #f59e0b; /* amber-500 */
  --starred-light: #fffbeb; /* amber-50 */
  --radius-sm: 8px;
  --radius-md: 12px;
  --radius-lg: 16px;
  --transition-fast: 0.15s ease;
  --transition-normal: 0.3s ease;
  --shadow-sm: 0 1px 3px rgba(0,0,0,0.05);
  --shadow-md: 0 4px 6px -1px rgba(0,0,0,0.05), 0 2px 4px -1px rgba(0,0,0,0.03);
  --shadow-lg: 0 10px 15px -3px rgba(0,0,0,0.05), 0 4px 6px -2px rgba(0,0,0,0.02);
}

[data-theme="dark"] {
  /* Dark Theme Palette */
  --bg-primary: #090d16; /* deep off-black */
  --bg-secondary: #111827; /* gray-900 */
  --bg-tertiary: #1f2937; /* gray-800 */
  --text-primary: #f9fafb; /* gray-50 */
  --text-secondary: #9ca3af; /* gray-400 */
  --text-muted: #6b7280; /* gray-500 */
  --border-color: #374151; /* gray-700 */
  --accent-color: #3b82f6;
  --accent-hover: #60a5fa; /* blue-400 */
  --accent-light: rgba(59, 130, 246, 0.15);
  --success-color: #34d399; /* emerald-400 */
  --success-light: rgba(52, 211, 153, 0.15);
  --error-color: #f87171; /* red-400 */
  --error-light: rgba(248, 113, 113, 0.15);
  --starred-color: #fbbf24; /* amber-400 */
  --starred-light: rgba(251, 191, 36, 0.15);
  --shadow-sm: 0 1px 2px rgba(0,0,0,0.2);
  --shadow-md: 0 4px 6px -1px rgba(0,0,0,0.3), 0 2px 4px -1px rgba(0,0,0,0.2);
  --shadow-lg: 0 10px 15px -3px rgba(0,0,0,0.4), 0 4px 6px -2px rgba(0,0,0,0.3);
}

/* Global Reset & Base */
* {
  box-sizing: border-box;
  margin: 0;
  padding: 0;
  -webkit-font-smoothing: antialiased;
}

body {
  font-family: 'Be Vietnam Pro', sans-serif;
  background-color: var(--bg-primary);
  color: var(--text-primary);
  line-height: 1.5;
  transition: background-color var(--transition-normal), color var(--transition-normal);
  min-height: 100vh;
}

/* Typography elements */
h1, h2, h3, h4 {
  font-family: 'Plus Jakarta Sans', sans-serif;
  font-weight: 700;
  letter-spacing: -0.02em;
}

code, .font-mono {
  font-family: 'JetBrains Mono', monospace;
  font-size: 0.9em;
}

/* Base Layout Container */
.app-container {
  max-width: 1200px;
  margin: 0 auto;
  padding: 1.5rem;
  display: flex;
  flex-direction: column;
  min-height: 100vh;
}

/* Header & Nav */
header {
  display: flex;
  justify-content: space-between;
  align-items: center;
  padding-bottom: 1.5rem;
  border-bottom: 1px solid var(--border-color);
  margin-bottom: 2rem;
}

.logo-section {
  display: flex;
  align-items: center;
  gap: 0.75rem;
  cursor: pointer;
}

.logo-icon {
  width: 2.25rem;
  height: 2.25rem;
  border-radius: var(--radius-md);
  background-color: var(--accent-color);
  display: flex;
  align-items: center;
  justify-content: center;
  color: white;
  font-weight: 800;
  font-family: 'Plus Jakarta Sans', sans-serif;
  font-size: 1.25rem;
  box-shadow: 0 0 15px rgba(59, 130, 246, 0.4);
}

.logo-text h1 {
  font-size: 1.25rem;
  background: linear-gradient(to right, var(--accent-color), var(--accent-hover));
  -webkit-background-clip: text;
  -webkit-text-fill-color: transparent;
}

.logo-text span {
  font-size: 0.75rem;
  color: var(--text-secondary);
  display: block;
}

.header-controls {
  display: flex;
  align-items: center;
  gap: 1rem;
}

/* Theme and general action buttons */
.btn-icon {
  background: var(--bg-secondary);
  border: 1px solid var(--border-color);
  color: var(--text-primary);
  width: 2.5rem;
  height: 2.5rem;
  border-radius: var(--radius-md);
  display: flex;
  align-items: center;
  justify-content: center;
  cursor: pointer;
  transition: all var(--transition-fast);
  box-shadow: var(--shadow-sm);
}

.btn-icon:hover {
  background: var(--bg-tertiary);
  border-color: var(--text-secondary);
}

.btn-icon:active {
  transform: scale(0.95);
}

/* App Views Management */
.app-view {
  display: none;
  animation: fadeIn 0.4s cubic-bezier(0.16, 1, 0.3, 1);
}

.app-view.active {
  display: block;
}

@keyframes fadeIn {
  from {
    opacity: 0;
    transform: translateY(8px);
  }
  to {
    opacity: 1;
    transform: translateY(0);
  }
}

/* Stats Bento Grid */
.stats-grid {
  display: grid;
  grid-template-cols: repeat(auto-fit, minmax(220px, 1fr));
  gap: 1.25rem;
  margin-bottom: 2.5rem;
}

.stat-card {
  background: var(--bg-secondary);
  border: 1px solid var(--border-color);
  border-radius: var(--radius-lg);
  padding: 1.5rem;
  display: flex;
  flex-direction: column;
  justify-content: space-between;
  box-shadow: var(--shadow-md);
  position: relative;
  overflow: hidden;
}

.stat-card::before {
  content: '';
  position: absolute;
  top: 0;
  left: 0;
  width: 4px;
  height: 100%;
  background: var(--border-color);
}

.stat-card.blue::before { background: var(--accent-color); }
.stat-card.emerald::before { background: var(--success-color); }
.stat-card.amber::before { background: var(--starred-color); }

.stat-label {
  font-size: 0.875rem;
  color: var(--text-secondary);
  font-weight: 500;
  margin-bottom: 0.5rem;
}

.stat-value {
  font-size: 2rem;
  font-weight: 700;
  font-family: 'Plus Jakarta Sans', sans-serif;
  color: var(--text-primary);
}

.stat-sub {
  font-size: 0.75rem;
  color: var(--text-muted);
  margin-top: 0.25rem;
}

/* Chapter Selection Section */
.section-title {
  font-size: 1.5rem;
  margin-bottom: 1.25rem;
  display: flex;
  align-items: center;
  justify-content: space-between;
}

.chapters-grid {
  display: grid;
  grid-template-cols: 1fr;
  gap: 1.5rem;
  margin-bottom: 3rem;
}

@media (min-width: 768px) {
  .chapters-grid {
    grid-template-cols: repeat(2, 1fr);
  }
}

@media (min-width: 1024px) {
  .chapters-grid {
    grid-template-cols: repeat(3, 1fr);
  }
}

.chapter-card {
  background: var(--bg-secondary);
  border: 1px solid var(--border-color);
  border-radius: var(--radius-lg);
  padding: 1.75rem;
  display: flex;
  flex-direction: column;
  justify-content: space-between;
  box-shadow: var(--shadow-md);
  transition: transform var(--transition-normal), border-color var(--transition-normal), box-shadow var(--transition-normal);
  min-height: 240px;
}

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

.chapter-card-header h3 {
  font-size: 1.15rem;
  margin-bottom: 0.5rem;
  line-height: 1.3;
}

.chapter-card-header p {
  font-size: 0.875rem;
  color: var(--text-secondary);
  margin-bottom: 1.25rem;
  min-height: 40px;
}

.chapter-progress {
  margin-bottom: 1.5rem;
}

.progress-info {
  display: flex;
  justify-content: space-between;
  font-size: 0.75rem;
  font-weight: 500;
  margin-bottom: 0.25rem;
}

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

.progress-bar-fill {
  background: var(--accent-color);
  height: 100%;
  width: 0%;
  border-radius: 3px;
  transition: width 0.8s cubic-bezier(0.16, 1, 0.3, 1);
}

.chapter-actions {
  display: grid;
  grid-template-cols: 1fr 1fr;
  gap: 0.75rem;
}

/* Main Buttons styling */
.btn {
  padding: 0.75rem 1rem;
  border-radius: var(--radius-md);
  font-size: 0.875rem;
  font-weight: 600;
  display: flex;
  align-items: center;
  justify-content: center;
  gap: 0.5rem;
  cursor: pointer;
  transition: all var(--transition-fast);
  border: none;
}

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

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

.btn-secondary {
  background-color: var(--bg-tertiary);
  color: var(--text-primary);
  border: 1px solid var(--border-color);
}

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

.btn:active {
  transform: scale(0.97);
}

/* Flashcard View CSS */
.view-header {
  display: flex;
  align-items: center;
  justify-content: space-between;
  margin-bottom: 1.5rem;
  flex-wrap: wrap;
  gap: 1rem;
}

.back-link {
  display: flex;
  align-items: center;
  gap: 0.5rem;
  color: var(--accent-color);
  font-weight: 600;
  text-decoration: none;
  cursor: pointer;
}

.back-link:hover {
  text-decoration: underline;
}

.view-title h2 {
  font-size: 1.5rem;
}

.view-title p {
  font-size: 0.875rem;
  color: var(--text-secondary);
}

/* 3D Flashcard Structure */
.flashcard-wrapper {
  perspective: 1200px;
  width: 100%;
  max-width: 720px;
  height: 440px;
  margin: 1.5rem auto 2rem auto;
}

.flashcard {
  position: relative;
  width: 100%;
  height: 100%;
  transform-style: preserve-3d;
  transition: transform 0.6s cubic-bezier(0.175, 0.885, 0.32, 1.275);
  cursor: pointer;
}

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

.card-face {
  position: absolute;
  width: 100%;
  height: 100%;
  backface-visibility: hidden;
  border-radius: var(--radius-lg);
  padding: 2rem;
  display: flex;
  flex-direction: column;
  justify-content: space-between;
  border: 1px solid var(--border-color);
  box-shadow: var(--shadow-lg);
}

.card-front {
  background-color: var(--bg-secondary);
  color: var(--text-primary);
}

.card-back {
  background-color: var(--bg-secondary);
  color: var(--text-primary);
  transform: rotateX(180deg);
}

.card-face::after {
  content: '';
  position: absolute;
  top: 0;
  left: 0;
  width: 100%;
  height: 4px;
  background: var(--accent-color);
  border-radius: var(--radius-lg) var(--radius-lg) 0 0;
}

.card-back::after {
  background: var(--success-color);
}

.card-badge {
  font-size: 0.75rem;
  text-transform: uppercase;
  letter-spacing: 0.1em;
  font-weight: 700;
  color: var(--text-muted);
}

.card-content {
  flex-grow: 1;
  display: flex;
  flex-direction: column;
  align-items: stretch;
  justify-content: flex-start;
  font-size: 1.4rem;
  font-family: 'Be Vietnam Pro', sans-serif;
  font-weight: 500;
  line-height: 1.5;
  overflow-y: auto;
  padding: 0.5rem 0.5rem 0.5rem 0;
  width: 100%;
}

.card-footer {
  display: flex;
  justify-content: space-between;
  align-items: center;
  width: 100%;
}

.card-index {
  font-size: 0.875rem;
  color: var(--text-secondary);
}

.star-btn {
  background: none;
  border: none;
  color: var(--text-muted);
  cursor: pointer;
  font-size: 1.25rem;
  transition: transform var(--transition-fast), color var(--transition-fast);
}

.star-btn:hover {
  transform: scale(1.15);
}

.star-btn.active {
  color: var(--starred-color);
}

.hint-tap {
  text-align: center;
  font-size: 0.75rem;
  color: var(--text-muted);
  margin-top: -1.25rem;
  margin-bottom: 2rem;
  display: flex;
  align-items: center;
  justify-content: center;
  gap: 0.25rem;
}

/* Study Control Buttons */
.study-controls {
  display: flex;
  justify-content: center;
  align-items: center;
  gap: 1rem;
  margin-bottom: 2rem;
  flex-wrap: wrap;
}

.btn-circle {
  width: 3.25rem;
  height: 3.25rem;
  border-radius: 50%;
  background: var(--bg-secondary);
  border: 1px solid var(--border-color);
  color: var(--text-primary);
  display: flex;
  align-items: center;
  justify-content: center;
  cursor: pointer;
  transition: all var(--transition-fast);
  box-shadow: var(--shadow-md);
  font-size: 1.25rem;
}

.btn-circle:hover {
  background: var(--bg-tertiary);
  border-color: var(--text-secondary);
}

.btn-circle:active {
  transform: scale(0.92);
}

.btn-circle.active {
  background-color: var(--accent-light);
  border-color: var(--accent-color);
  color: var(--accent-color);
}

.grading-controls {
  display: flex;
  justify-content: center;
  gap: 1rem;
  max-width: 450px;
  margin: 0 auto;
}

.btn-grade {
  flex: 1;
  padding: 0.875rem 1rem;
  font-size: 0.9rem;
}

.btn-grade.learn-again {
  background-color: var(--error-light);
  color: var(--error-color);
  border: 1px solid var(--error-color);
}

.btn-grade.learn-again:hover {
  background-color: var(--error-color);
  color: white;
}

.btn-grade.got-it {
  background-color: var(--success-light);
  color: var(--success-color);
  border: 1px solid var(--success-color);
}

.btn-grade.got-it:hover {
  background-color: var(--success-color);
  color: white;
}

/* Quiz Mode CSS */
.quiz-wrapper {
  max-width: 700px;
  margin: 0 auto;
}

.quiz-card {
  background: var(--bg-secondary);
  border: 1px solid var(--border-color);
  border-radius: var(--radius-lg);
  padding: 2.25rem;
  box-shadow: var(--shadow-lg);
  margin-bottom: 1.5rem;
}

.quiz-question {
  font-size: 1.15rem;
  font-weight: 600;
  line-height: 1.4;
  margin-bottom: 2rem;
  color: var(--text-primary);
}

.options-container {
  display: grid;
  grid-template-cols: 1fr;
  gap: 1rem;
}

.option-btn {
  background: var(--bg-secondary);
  border: 1.5px solid var(--border-color);
  border-radius: var(--radius-md);
  padding: 1rem 1.25rem;
  text-align: left;
  font-size: 0.95rem;
  color: var(--text-primary);
  font-weight: 500;
  cursor: pointer;
  transition: all var(--transition-fast);
  display: flex;
  align-items: flex-start;
  gap: 0.75rem;
}

.option-prefix {
  background: var(--bg-tertiary);
  border: 1px solid var(--border-color);
  color: var(--text-secondary);
  font-weight: 700;
  width: 1.5rem;
  height: 1.5rem;
  border-radius: 6px;
  display: flex;
  align-items: center;
  justify-content: center;
  flex-shrink: 0;
  font-size: 0.75rem;
  margin-top: 0.1rem;
}

.option-text {
  flex-grow: 1;
}

.option-btn:hover:not(.disabled) {
  border-color: var(--accent-color);
  background: var(--bg-tertiary);
}

.option-btn:active:not(.disabled) {
  transform: scale(0.98);
}

.option-btn.disabled {
  cursor: not-allowed;
}

/* Correct/Incorrect Grade Styling */
.option-btn.correct {
  border-color: var(--success-color);
  background-color: var(--success-light);
}

.option-btn.correct .option-prefix {
  background-color: var(--success-color);
  color: white;
  border-color: var(--success-color);
}

.option-btn.incorrect {
  border-color: var(--error-color);
  background-color: var(--error-light);
}

.option-btn.incorrect .option-prefix {
  background-color: var(--error-color);
  color: white;
  border-color: var(--error-color);
}

.option-btn.faded {
  opacity: 0.5;
}

.quiz-feedback {
  margin-top: 1.5rem;
  padding: 1rem;
  border-radius: var(--radius-md);
  font-size: 0.9rem;
  display: none;
}

.quiz-feedback.correct {
  display: block;
  background-color: var(--success-light);
  color: var(--success-color);
  border: 1px dashed var(--success-color);
}

.quiz-feedback.incorrect {
  display: block;
  background-color: var(--error-light);
  color: var(--error-color);
  border: 1px dashed var(--error-color);
}

.quiz-next-actions {
  display: flex;
  justify-content: flex-end;
  margin-top: 1.5rem;
}

/* Quiz Summary Screen */
.summary-container {
  max-width: 600px;
  margin: 0 auto;
  background: var(--bg-secondary);
  border: 1px solid var(--border-color);
  border-radius: var(--radius-lg);
  padding: 2.5rem;
  box-shadow: var(--shadow-lg);
  text-align: center;
}

.summary-illustration {
  font-size: 4rem;
  margin-bottom: 1.5rem;
}

.summary-title {
  font-size: 2rem;
  margin-bottom: 0.5rem;
}

.summary-text {
  color: var(--text-secondary);
  margin-bottom: 2rem;
}

.summary-stats {
  display: grid;
  grid-template-cols: 1fr 1fr;
  gap: 1.5rem;
  margin-bottom: 2rem;
}

.summary-stat-box {
  background: var(--bg-primary);
  border: 1px solid var(--border-color);
  border-radius: var(--radius-md);
  padding: 1.25rem;
}

.summary-stat-val {
  font-size: 1.75rem;
  font-weight: 700;
  font-family: 'Plus Jakarta Sans', sans-serif;
  color: var(--accent-color);
}

.summary-stat-val.success {
  color: var(--success-color);
}

.summary-stat-lbl {
  font-size: 0.75rem;
  color: var(--text-secondary);
  margin-top: 0.25rem;
  text-transform: uppercase;
  font-weight: 600;
}

.summary-actions {
  display: flex;
  gap: 1rem;
  justify-content: center;
  flex-wrap: wrap;
}

/* Empty review pools */
.empty-state {
  text-align: center;
  padding: 3rem 1.5rem;
  background: var(--bg-secondary);
  border: 1px dashed var(--border-color);
  border-radius: var(--radius-lg);
  margin-top: 2rem;
}

.empty-icon {
  font-size: 3rem;
  margin-bottom: 1rem;
  color: var(--text-muted);
}

.empty-state h3 {
  font-size: 1.25rem;
  margin-bottom: 0.5rem;
}

.empty-state p {
  color: var(--text-secondary);
  margin-bottom: 1.5rem;
}

/* Footer Section */
footer {
  margin-top: auto;
  padding: 2rem 0 1rem;
  border-top: 1px solid var(--border-color);
  text-align: center;
  font-size: 0.825rem;
  color: var(--text-muted);
}

footer a {
  color: var(--accent-color);
  text-decoration: none;
}

footer a:hover {
  text-decoration: underline;
}

/* Custom transitions and states */
.progress-bar-fill {
  position: relative;
}

.progress-bar-fill::after {
  content: '';
  position: absolute;
  top: 0;
  left: 0;
  right: 0;
  bottom: 0;
  background: linear-gradient(
    90deg,
    rgba(255, 255, 255, 0) 0%,
    rgba(255, 255, 255, 0.2) 50%,
    rgba(255, 255, 255, 0) 100%
  );
  animation: shine 2s infinite;
}

@keyframes shine {
  0% { transform: translateX(-100%); }
  100% { transform: translateX(100%); }
}