/* ============================================
   Kwizz — Modern Quiz App Styles
   Light + Dark mode via CSS custom properties
   ============================================ */

/* --- CSS Variables (Light Theme) --- */
:root {
  --color-bg: #f8fafc;
  --color-bg-alt: #f1f5f9;
  --color-surface: #ffffff;
  --color-surface-hover: #f8fafc;
  --color-text: #0f172a;
  --color-text-secondary: #475569;
  --color-text-muted: #94a3b8;
  --color-border: #e2e8f0;
  --color-border-hover: #cbd5e1;

  --color-primary: #6366f1;
  --color-primary-hover: #4f46e5;
  --color-primary-light: #eef2ff;
  --color-primary-text: #ffffff;

  --color-success: #10b981;
  --color-success-bg: #ecfdf5;
  --color-success-text: #065f46;

  --color-error: #ef4444;
  --color-error-bg: #fef2f2;
  --color-error-text: #991b1b;

  --color-warning: #f59e0b;
  --color-warning-bg: #fffbeb;
  --color-warning-text: #92400e;

  --shadow-xs: 0 1px 2px rgba(0,0,0,0.04);
  --shadow-sm: 0 1px 3px rgba(0,0,0,0.06), 0 1px 2px rgba(0,0,0,0.04);
  --shadow: 0 1px 3px rgba(0,0,0,0.08), 0 1px 2px rgba(0,0,0,0.04);
  --shadow-md: 0 4px 6px -1px rgba(0,0,0,0.07), 0 2px 4px -1px rgba(0,0,0,0.04);
  --shadow-lg: 0 10px 15px -3px rgba(0,0,0,0.08), 0 4px 6px -2px rgba(0,0,0,0.03);
  --shadow-xl: 0 20px 25px -5px rgba(0,0,0,0.08), 0 10px 10px -5px rgba(0,0,0,0.02);

  --gradient-primary: linear-gradient(135deg, #6366f1 0%, #8b5cf6 100%);
  --gradient-surface: linear-gradient(180deg, #ffffff 0%, #f8fafc 100%);

  --radius-xs: 6px;
  --radius-sm: 10px;
  --radius: 16px;
  --radius-lg: 20px;
  --radius-full: 9999px;

  --transition: 200ms cubic-bezier(0.4, 0, 0.2, 1);
  --transition-slow: 350ms cubic-bezier(0.4, 0, 0.2, 1);

  --font-sans: -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, "Helvetica Neue", Arial, "Noto Sans", sans-serif;
  --font-mono: "SF Mono", "Fira Code", "Fira Mono", "Roboto Mono", monospace;
}

/* --- Dark Theme --- */
[data-theme="dark"] {
  --color-bg: #0b1120;
  --color-bg-alt: #111827;
  --color-surface: #1a2332;
  --color-surface-hover: #1f2a3d;
  --color-text: #f1f5f9;
  --color-text-secondary: #94a3b8;
  --color-text-muted: #64748b;
  --color-border: #2d3a4f;
  --color-border-hover: #475569;

  --color-primary: #818cf8;
  --color-primary-hover: #6366f1;
  --color-primary-light: #1e1b4b;
  --color-primary-text: #ffffff;

  --color-success: #34d399;
  --color-success-bg: #022c22;
  --color-success-text: #a7f3d0;

  --color-error: #f87171;
  --color-error-bg: #450a0a;
  --color-error-text: #fca5a5;

  --color-warning: #fbbf24;
  --color-warning-bg: #451a03;
  --color-warning-text: #fde68a;

  --shadow-xs: 0 1px 2px rgba(0,0,0,0.2);
  --shadow-sm: 0 1px 3px rgba(0,0,0,0.3);
  --shadow: 0 1px 3px rgba(0,0,0,0.35);
  --shadow-md: 0 4px 6px rgba(0,0,0,0.35);
  --shadow-lg: 0 10px 15px rgba(0,0,0,0.4);
  --shadow-xl: 0 20px 25px rgba(0,0,0,0.45);

  --gradient-primary: linear-gradient(135deg, #818cf8 0%, #a78bfa 100%);
  --gradient-surface: linear-gradient(180deg, #1a2332 0%, #151d2b 100%);
}

/* --- Reset & Base --- */
*, *::before, *::after {
  box-sizing: border-box;
  margin: 0;
  padding: 0;
}

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

body {
  font-family: var(--font-sans);
  background: var(--color-bg);
  color: var(--color-text);
  line-height: 1.6;
  min-height: 100vh;
  min-height: 100dvh;
  display: flex;
  justify-content: center;
  transition: background var(--transition-slow), color var(--transition-slow);
}

/* --- App Container --- */
.app-container {
  width: 100%;
  max-width: 720px;
  min-height: 100vh;
  min-height: 100dvh;
  display: flex;
  flex-direction: column;
}

/* --- Header --- */
.app-header {
  display: flex;
  align-items: center;
  justify-content: space-between;
  padding: 0.875rem 1.25rem;
  background: var(--color-surface);
  border-bottom: 1px solid var(--color-border);
  position: sticky;
  top: 0;
  z-index: 20;
  backdrop-filter: blur(12px);
  background: var(--color-surface);
  transition: background var(--transition-slow), border-color var(--transition-slow);
}

@supports (backdrop-filter: blur(12px)) {
  .app-header {
    background: color-mix(in srgb, var(--color-surface) 85%, transparent);
  }
}

.app-logo {
  font-size: 1.35rem;
  font-weight: 800;
  letter-spacing: -0.5px;
  cursor: pointer;
  user-select: none;
  background: var(--gradient-primary);
  -webkit-background-clip: text;
  -webkit-text-fill-color: transparent;
  background-clip: text;
}

.app-nav {
  display: flex;
  align-items: center;
  gap: 0.25rem;
}

/* --- Theme Toggle --- */
.theme-toggle {
  width: 38px;
  height: 38px;
  border-radius: var(--radius-full);
  border: 1px solid var(--color-border);
  background: var(--color-surface);
  cursor: pointer;
  display: flex;
  align-items: center;
  justify-content: center;
  font-size: 1.125rem;
  transition: all var(--transition);
  color: var(--color-text-secondary);
  flex-shrink: 0;
}

.theme-toggle:hover {
  border-color: var(--color-primary);
  color: var(--color-primary);
  background: var(--color-primary-light);
}

/* --- Main --- */
.app-main {
  flex: 1;
  padding: 1.25rem;
  display: flex;
  flex-direction: column;
  gap: 1.25rem;
}

.app-footer {
  text-align: center;
  padding: 1rem 1.25rem;
  font-size: 0.75rem;
  color: var(--color-text-muted);
  border-top: 1px solid var(--color-border);
  transition: border-color var(--transition-slow);
}

/* --- Buttons --- */
.btn {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  gap: 0.5rem;
  padding: 0.625rem 1.25rem;
  border: none;
  border-radius: var(--radius-sm);
  font-size: 0.9rem;
  font-weight: 600;
  color: var(--color-text);
  cursor: pointer;
  transition: all var(--transition);
  font-family: var(--font-sans);
  line-height: 1.4;
  text-decoration: none;
  position: relative;
  overflow: hidden;
}

.btn:active {
  transform: scale(0.96);
}

.btn-primary {
  background: var(--gradient-primary);
  color: var(--color-primary-text);
  box-shadow: var(--shadow-sm), 0 0 0 0 var(--color-primary);
  transition: all var(--transition), box-shadow var(--transition-slow);
}

.btn-primary:hover {
  box-shadow: var(--shadow-md), 0 0 0 4px color-mix(in srgb, var(--color-primary) 15%, transparent);
  transform: translateY(-1px);
}

.btn-primary:active {
  transform: translateY(0) scale(0.96);
}

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

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

.btn-ghost {
  background: transparent;
  color: var(--color-text-secondary);
  padding: 0.5rem 0.75rem;
}

.btn-ghost:hover {
  background: var(--color-bg-alt);
  color: var(--color-text);
}

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

.btn-danger:hover {
  background: var(--color-error-bg);
  border-color: var(--color-error);
}

.btn-sm {
  padding: 0.375rem 0.75rem;
  font-size: 0.8125rem;
}

.btn-block {
  width: 100%;
}

.btn:disabled {
  opacity: 0.5;
  cursor: not-allowed;
  transform: none !important;
  box-shadow: none !important;
}

/* --- Cards --- */
.card {
  background: var(--color-surface);
  border-radius: var(--radius);
  padding: 1.5rem;
  box-shadow: var(--shadow-sm);
  border: 1px solid var(--color-border);
  transition: background var(--transition-slow), border-color var(--transition-slow), box-shadow var(--transition-slow);
}

.card-accent {
  border-top: 3px solid var(--color-primary);
}

.card-header {
  margin-bottom: 1rem;
}

.card-header h2 {
  font-size: 1.2rem;
  font-weight: 700;
  letter-spacing: -0.2px;
}

.card-header p {
  color: var(--color-text-secondary);
  font-size: 0.85rem;
  margin-top: 0.25rem;
}

/* --- Home / Quiz List --- */
.quiz-list {
  display: flex;
  flex-direction: column;
  gap: 0.625rem;
}

.quiz-card {
  display: flex;
  flex-direction: column;
  gap: 0.375rem;
  padding: 1.125rem 1.25rem;
  background: var(--color-surface);
  border: 1px solid var(--color-border);
  border-radius: var(--radius);
  cursor: pointer;
  transition: all var(--transition);
  position: relative;
  overflow: hidden;
}

.quiz-card::before {
  content: '';
  position: absolute;
  left: 0;
  top: 0;
  bottom: 0;
  width: 3px;
  background: var(--gradient-primary);
  opacity: 0;
  transition: opacity var(--transition);
  border-radius: 0 2px 2px 0;
}

.quiz-card:hover {
  border-color: var(--color-primary);
  box-shadow: var(--shadow-md);
  transform: translateY(-1px);
}

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

.quiz-card:active {
  transform: translateY(0);
}

.quiz-card-title {
  font-size: 1.05rem;
  font-weight: 700;
  letter-spacing: -0.2px;
}

.quiz-card-desc {
  font-size: 0.85rem;
  color: var(--color-text-secondary);
}

.quiz-card-meta {
  display: flex;
  gap: 0.75rem;
  font-size: 0.8rem;
  color: var(--color-text-muted);
  align-items: center;
}

.quiz-card-badge {
  display: inline-flex;
  align-items: center;
  gap: 0.25rem;
  padding: 0.15rem 0.5rem;
  border-radius: var(--radius-full);
  font-size: 0.7rem;
  font-weight: 600;
  background: var(--color-bg-alt);
}

.quiz-card-badge.new {
  background: var(--color-success-bg);
  color: var(--color-success-text);
}

/* --- File Loader --- */
.file-loader-card {
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 0.75rem;
  padding: 1rem 1.25rem;
}

.file-loader {
  display: flex;
  align-items: center;
  gap: 0.75rem;
  flex: 1;
}

.file-loader-icon {
  font-size: 1.5rem;
  flex-shrink: 0;
}

/* --- Setup --- */
.setup-options {
  display: flex;
  flex-direction: column;
  gap: 0.75rem;
}

.option-row {
  display: flex;
  align-items: center;
  justify-content: space-between;
  padding: 0.875rem 1rem;
  background: var(--color-bg-alt);
  border-radius: var(--radius-sm);
  transition: background var(--transition-slow);
  gap: 1rem;
}

.option-label {
  font-weight: 600;
  font-size: 0.9rem;
}

.option-desc {
  font-size: 0.8rem;
  color: var(--color-text-muted);
  margin-top: 0.125rem;
}

/* --- Toggle Switch --- */
.toggle {
  position: relative;
  width: 48px;
  height: 28px;
  flex-shrink: 0;
}

.toggle input {
  opacity: 0;
  width: 0;
  height: 0;
}

.toggle-slider {
  position: absolute;
  inset: 0;
  background: var(--color-border-hover);
  border-radius: var(--radius-full);
  cursor: pointer;
  transition: background var(--transition);
}

.toggle-slider::before {
  content: "";
  position: absolute;
  width: 22px;
  height: 22px;
  left: 3px;
  top: 3px;
  background: #fff;
  border-radius: 50%;
  transition: transform var(--transition);
  box-shadow: 0 1px 3px rgba(0,0,0,0.15);
}

.toggle input:checked + .toggle-slider {
  background: var(--color-primary);
}

.toggle input:checked + .toggle-slider::before {
  transform: translateX(20px);
}

/* --- Quiz Active --- */
.quiz-progress {
  display: flex;
  align-items: center;
  gap: 0.625rem;
}

.progress-bar {
  flex: 1;
  height: 8px;
  background: var(--color-bg-alt);
  border-radius: var(--radius-full);
  overflow: hidden;
}

.progress-bar-fill {
  height: 100%;
  background: var(--gradient-primary);
  border-radius: var(--radius-full);
  transition: width 0.4s cubic-bezier(0.4, 0, 0.2, 1);
}

.progress-text {
  font-size: 0.8rem;
  font-weight: 700;
  color: var(--color-text-muted);
  white-space: nowrap;
  min-width: 2.5rem;
  text-align: right;
}

.question-image {
  width: 100%;
  max-height: 280px;
  object-fit: contain;
  border-radius: var(--radius-sm);
  margin: 0.75rem 0;
  background: var(--color-bg-alt);
  border: 1px solid var(--color-border);
}

.question-text {
  font-size: 1.1rem;
  font-weight: 650;
  margin-bottom: 1rem;
  line-height: 1.5;
  letter-spacing: -0.1px;
}

.answers-list {
  display: flex;
  flex-direction: column;
  gap: 0.5rem;
}

.answer-btn {
  display: flex;
  align-items: center;
  gap: 0.75rem;
  padding: 0.875rem 1rem;
  border: 2px solid var(--color-border);
  border-radius: var(--radius-sm);
  background: var(--color-surface);
  color: var(--color-text);
  cursor: pointer;
  text-align: left;
  font-family: var(--font-sans);
  font-size: 0.9rem;
  font-weight: 500;
  transition: all var(--transition);
  line-height: 1.4;
  position: relative;
}

.answer-btn:hover:not(.answer-correct):not(.answer-incorrect):not(.answer-disabled) {
  border-color: var(--color-primary);
  background: var(--color-primary-light);
  transform: translateX(2px);
}

.answer-btn.answer-correct {
  border-color: var(--color-success);
  background: var(--color-success-bg);
}

.answer-btn.answer-incorrect {
  border-color: var(--color-error);
  background: var(--color-error-bg);
}

.answer-btn.answer-disabled {
  cursor: default;
}

.answer-btn.answer-disabled:not(.answer-correct):not(.answer-incorrect) {
  opacity: 0.5;
}

.answer-btn.answer-selected {
  border-color: var(--color-primary);
  background: var(--color-primary-light);
  box-shadow: 0 0 0 1px var(--color-primary);
}

.answer-letter {
  display: flex;
  align-items: center;
  justify-content: center;
  width: 32px;
  height: 32px;
  border-radius: var(--radius-xs);
  background: var(--color-bg-alt);
  font-weight: 700;
  font-size: 0.85rem;
  flex-shrink: 0;
  transition: all var(--transition);
}

.answer-correct .answer-letter {
  background: var(--color-success);
  color: #fff;
}

.answer-incorrect .answer-letter {
  background: var(--color-error);
  color: #fff;
}

.answer-image {
  width: 56px;
  height: 56px;
  object-fit: cover;
  border-radius: var(--radius-xs);
  flex-shrink: 0;
  border: 1px solid var(--color-border);
}

.answer-text {
  flex: 1;
}

.feedback-banner {
  padding: 0.75rem 1rem;
  border-radius: var(--radius-sm);
  font-weight: 600;
  display: flex;
  align-items: center;
  gap: 0.5rem;
  font-size: 0.9rem;
  margin-top: 0.75rem;
  animation: fadeInUp 0.25s ease;
}

.feedback-correct {
  background: var(--color-success-bg);
  color: var(--color-success-text);
}

.feedback-incorrect {
  background: var(--color-error-bg);
  color: var(--color-error-text);
}

@keyframes fadeInUp {
  from { opacity: 0; transform: translateY(6px); }
  to { opacity: 1; transform: translateY(0); }
}

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

/* --- Results --- */
.results-summary {
  display: grid;
  grid-template-columns: repeat(2, 1fr);
  gap: 0.75rem;
  margin-bottom: 1rem;
}

.result-stat {
  text-align: center;
  padding: 1.125rem 0.75rem;
  background: var(--color-bg-alt);
  border-radius: var(--radius-sm);
  transition: background var(--transition-slow);
}

.result-stat-value {
  font-size: 1.75rem;
  font-weight: 800;
  letter-spacing: -0.5px;
  color: var(--color-primary);
  transition: color var(--transition-slow);
}

.result-stat-value.score-high { color: var(--color-success); }
.result-stat-value.score-mid { color: var(--color-warning); }
.result-stat-value.score-low { color: var(--color-error); }

.result-stat-label {
  font-size: 0.78rem;
  color: var(--color-text-muted);
  margin-top: 0.2rem;
}

.results-breakdown {
  display: flex;
  flex-direction: column;
  gap: 0.375rem;
  max-height: 360px;
  overflow-y: auto;
}

.result-item {
  display: flex;
  align-items: center;
  gap: 0.625rem;
  padding: 0.625rem 0.875rem;
  background: var(--color-bg-alt);
  border-radius: var(--radius-sm);
  font-size: 0.85rem;
  transition: background var(--transition-slow);
}

.result-item-icon {
  font-size: 1.125rem;
  flex-shrink: 0;
}

.result-item-text {
  flex: 1;
  font-weight: 500;
  white-space: nowrap;
  overflow: hidden;
  text-overflow: ellipsis;
}

.result-item-time {
  color: var(--color-text-muted);
  font-size: 0.8rem;
  flex-shrink: 0;
  font-variant-numeric: tabular-nums;
}

/* --- History --- */
.history-list {
  display: flex;
  flex-direction: column;
  gap: 0.625rem;
}

.history-item {
  padding: 1rem 1.25rem;
  background: var(--color-surface);
  border: 1px solid var(--color-border);
  border-radius: var(--radius);
  cursor: pointer;
  transition: all var(--transition);
}

.history-item:hover {
  border-color: var(--color-primary);
  box-shadow: var(--shadow-md);
  transform: translateY(-1px);
}

.history-quiz-name {
  font-weight: 700;
  font-size: 0.95rem;
}

.history-meta {
  display: flex;
  gap: 0.75rem;
  font-size: 0.8rem;
  color: var(--color-text-muted);
  margin-top: 0.2rem;
}

.history-score {
  font-weight: 700;
  margin-top: 0.25rem;
}

.history-score.score-high { color: var(--color-success); }
.history-score.score-mid { color: var(--color-warning); }
.history-score.score-low { color: var(--color-error); }

/* --- Empty State --- */
.empty-state {
  text-align: center;
  padding: 2.5rem 1rem;
  color: var(--color-text-muted);
}

.empty-state-icon {
  font-size: 3rem;
  margin-bottom: 0.75rem;
}

.empty-state h3 {
  font-size: 1.1rem;
  color: var(--color-text);
  margin-bottom: 0.25rem;
  font-weight: 700;
}

.empty-state p {
  font-size: 0.85rem;
}

/* --- Error --- */
.error-banner {
  padding: 1rem;
  background: var(--color-error-bg);
  border: 1px solid color-mix(in srgb, var(--color-error) 30%, transparent);
  color: var(--color-error-text);
  border-radius: var(--radius-sm);
  font-weight: 500;
  font-size: 0.9rem;
}

.error-banner code {
  font-family: var(--font-mono);
  font-size: 0.8rem;
  background: rgba(0,0,0,0.08);
  padding: 0.1rem 0.35rem;
  border-radius: 3px;
}

.loading {
  text-align: center;
  padding: 2.5rem;
  color: var(--color-text-muted);
}

.loading p {
  animation: pulse 1.5s ease infinite;
}

/* --- Backup / Data Section --- */
.backup-section {
  margin-top: 0.5rem;
}

.backup-section h3 {
  font-size: 0.95rem;
  font-weight: 700;
  margin-bottom: 0.75rem;
}

.backup-actions {
  display: flex;
  flex-direction: column;
  gap: 0.5rem;
}

.data-stats {
  display: flex;
  gap: 1rem;
  font-size: 0.8rem;
  color: var(--color-text-muted);
  margin-bottom: 0.75rem;
  flex-wrap: wrap;
}

.data-stats span {
  display: inline-flex;
  align-items: center;
  gap: 0.25rem;
}

/* --- Stored Quizzes Section --- */
.stored-quiz-item {
  display: flex;
  align-items: center;
  justify-content: space-between;
  padding: 0.625rem 0.875rem;
  background: var(--color-bg-alt);
  border-radius: var(--radius-sm);
  margin-bottom: 0.375rem;
  gap: 0.5rem;
}

.stored-quiz-info {
  flex: 1;
  min-width: 0;
}

.stored-quiz-title {
  font-weight: 600;
  font-size: 0.875rem;
}

.stored-quiz-meta {
  font-size: 0.75rem;
  color: var(--color-text-muted);
}

/* --- Modal --- */
.modal-overlay {
  position: fixed;
  inset: 0;
  background: rgba(0,0,0,0.5);
  z-index: 100;
  display: flex;
  align-items: center;
  justify-content: center;
  padding: 1rem;
  animation: fadeIn 0.2s ease;
}

.modal {
  background: var(--color-surface);
  border-radius: var(--radius-lg);
  padding: 1.5rem;
  max-width: 440px;
  width: 100%;
  box-shadow: var(--shadow-xl);
  border: 1px solid var(--color-border);
  animation: fadeInUp 0.25s ease;
}

.modal h3 {
  font-size: 1.1rem;
  font-weight: 700;
  margin-bottom: 0.5rem;
}

.modal p {
  font-size: 0.85rem;
  color: var(--color-text-secondary);
  margin-bottom: 1rem;
}

.modal-actions {
  display: flex;
  gap: 0.5rem;
  justify-content: flex-end;
}

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

/* --- Select input --- */
select {
  padding: 0.5rem 0.75rem;
  border-radius: var(--radius-xs);
  border: 1px solid var(--color-border);
  font-family: var(--font-sans);
  font-size: 0.875rem;
  background: var(--color-surface);
  color: var(--color-text);
  cursor: pointer;
  transition: border-color var(--transition);
}

select:focus {
  outline: none;
  border-color: var(--color-primary);
  box-shadow: 0 0 0 3px color-mix(in srgb, var(--color-primary) 15%, transparent);
}

/* --- Responsive --- */
@media (max-width: 480px) {
  .app-main {
    padding: 0.75rem;
    gap: 0.75rem;
  }

  .app-header {
    padding: 0.75rem 1rem;
  }

  .card {
    padding: 1.125rem;
  }

  .quiz-card {
    padding: 0.875rem 1rem;
  }

  .results-summary {
    grid-template-columns: repeat(2, 1fr);
    gap: 0.5rem;
  }

  .result-stat {
    padding: 0.875rem 0.5rem;
  }

  .result-stat-value {
    font-size: 1.4rem;
  }

  .answer-image {
    width: 44px;
    height: 44px;
  }

  .answer-letter {
    width: 28px;
    height: 28px;
    font-size: 0.75rem;
  }

  .answer-btn {
    padding: 0.75rem 0.875rem;
    font-size: 0.85rem;
  }
}

/* --- Scrollbar --- */
.results-breakdown::-webkit-scrollbar {
  width: 4px;
}

.results-breakdown::-webkit-scrollbar-track {
  background: transparent;
}

.results-breakdown::-webkit-scrollbar-thumb {
  background: var(--color-border-hover);
  border-radius: 2px;
}

/* --- Print-friendly: hide interactive elements --- */
@media print {
  .app-header, .app-footer, .btn {
    display: none;
  }
}