/* ===========================================
   CF Random Problem Picker — Styles
   =========================================== */

/* --- 1. CSS Custom Properties --- */
:root {
  --bg-primary: #f8f9fa;
  --bg-secondary: #ffffff;
  --bg-tertiary: #e9ecef;
  --text-primary: #212529;
  --text-secondary: #6c757d;
  --text-muted: #adb5bd;
  --border-color: #dee2e6;
  --accent: #3b82f6;
  --accent-hover: #2563eb;
  --accent-light: #dbeafe;
  --card-bg: #ffffff;
  --card-shadow: 0 2px 12px rgba(0, 0, 0, 0.08);
  --card-shadow-hover: 0 4px 20px rgba(0, 0, 0, 0.12);
  --chip-bg: #e9ecef;
  --chip-bg-selected: #3b82f6;
  --chip-text: #495057;
  --chip-text-selected: #ffffff;
  --danger: #dc3545;
  --danger-hover: #c82333;
  --warning-bg: #fff3cd;
  --warning-text: #856404;
  --error-bg: #f8d7da;
  --error-text: #721c24;
  --info-bg: #d1ecf1;
  --info-text: #0c5460;
  --success-bg: #d4edda;
  --success-text: #155724;

  /* Codeforces rating colors */
  --cf-newbie: #808080;
  --cf-pupil: #008000;
  --cf-specialist: #03a89e;
  --cf-expert: #0000ff;
  --cf-cm: #aa00aa;
  --cf-master: #ff8c00;
  --cf-grandmaster: #ff0000;

  --radius-sm: 6px;
  --radius-md: 10px;
  --radius-lg: 14px;
  --transition: 0.2s ease;
}

/* --- 2. Reset & Base --- */
*,
*::before,
*::after {
  box-sizing: border-box;
  margin: 0;
  padding: 0;
}

/* Ensure [hidden] always works even when element has an explicit display value */
[hidden] {
  display: none !important;
}

button, input, select, textarea {
  font-family: inherit;
  font-size: inherit;
}

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

body {
  font-family: "Noto Sans SC", -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, Oxygen,
    Ubuntu, Cantarell, "Helvetica Neue", sans-serif;
  background: var(--bg-primary);
  color: var(--text-primary);
  line-height: 1.6;
  min-height: 100vh;
}

/* --- 3. Layout --- */
.container {
  max-width: 900px;
  margin: 0 auto;
  padding: 24px 20px 60px;
}

/* --- 4. Header --- */
.header {
  display: flex;
  align-items: center;
  justify-content: space-between;
  flex-wrap: wrap;
  gap: 12px;
  padding-bottom: 20px;
  border-bottom: 2px solid var(--border-color);
  margin-bottom: 24px;
}

.logo {
  font-size: 1.6rem;
  font-weight: 700;
  color: var(--text-primary);
}

.header-actions {
  display: flex;
  gap: 8px;
}

/* --- 4.1 Tab Bar --- */
.tab-bar {
  display: flex;
  gap: 0;
  margin-bottom: 16px;
  border-bottom: 2px solid var(--border-color);
}

.tab-btn {
  padding: 10px 24px;
  font-size: 0.9375rem;
  font-weight: 600;
  color: var(--text-secondary);
  background: none;
  border: none;
  border-bottom: 3px solid transparent;
  cursor: pointer;
  transition: color var(--transition), border-color var(--transition);
  margin-bottom: -2px;
}
.tab-btn:hover {
  color: var(--accent);
}
.tab-btn.tab-active {
  color: var(--accent);
  border-bottom-color: var(--accent);
}

/* --- 4.2 Handle Bar --- */
.handle-bar {
  display: flex;
  align-items: center;
  gap: 10px;
  flex-wrap: wrap;
  padding: 12px 20px;
  background: var(--bg-secondary);
  border: 1px solid var(--border-color);
  border-radius: var(--radius-md);
  margin-bottom: 20px;
}

.handle-label {
  font-size: 0.9375rem;
  font-weight: 600;
  color: var(--text-primary);
  white-space: nowrap;
}

.handle-input {
  flex: 1;
  min-width: 160px;
  max-width: 280px;
  padding: 8px 12px;
  font-size: 0.9375rem;
  font-family: inherit;
  color: var(--text-primary);
  background: var(--bg-primary);
  border: 1px solid var(--border-color);
  border-radius: var(--radius-sm);
  outline: none;
  transition: border-color var(--transition), box-shadow var(--transition);
}
.handle-input:focus {
  border-color: var(--accent);
  box-shadow: 0 0 0 3px rgba(59, 130, 246, 0.15);
}

.handle-status {
  font-size: 0.8125rem;
  color: var(--text-muted);
}
.handle-status.loading {
  color: var(--accent);
}
.handle-status.success {
  color: #28a745;
}
.handle-status.error {
  color: var(--danger);
}

/* --- 5. Buttons --- */
.btn-icon {
  display: inline-flex;
  align-items: center;
  gap: 6px;
  padding: 8px 16px;
  font-size: 0.875rem;
  font-weight: 500;
  color: var(--accent);
  background: var(--accent-light);
  border: 1px solid transparent;
  border-radius: var(--radius-sm);
  cursor: pointer;
  transition: background var(--transition), transform var(--transition);
}
.btn-icon:hover {
  background: #bfdbfe;
}
.btn-icon:active {
  transform: scale(0.97);
}

.btn-roll {
  display: block;
  width: 100%;
  max-width: 420px;
  margin: 0 auto;
  padding: 18px 48px;
  font-size: 1.25rem;
  font-weight: 700;
  color: #ffffff;
  background: var(--accent);
  border: none;
  border-radius: var(--radius-lg);
  cursor: pointer;
  transition: background var(--transition), transform var(--transition),
    box-shadow var(--transition);
  box-shadow: 0 4px 14px rgba(59, 130, 246, 0.35);
}
.btn-roll:hover:not(:disabled) {
  background: var(--accent-hover);
  box-shadow: 0 6px 20px rgba(59, 130, 246, 0.45);
  transform: translateY(-1px);
}
.btn-roll:active:not(:disabled) {
  transform: scale(0.97);
}
.btn-roll:disabled {
  background: var(--text-muted);
  box-shadow: none;
  cursor: not-allowed;
}

.preset-btn {
  padding: 6px 14px;
  font-size: 0.8125rem;
  font-weight: 500;
  color: var(--text-secondary);
  background: var(--bg-tertiary);
  border: 1px solid var(--border-color);
  border-radius: var(--radius-sm);
  cursor: pointer;
  transition: all var(--transition);
  white-space: nowrap;
}
.preset-btn:hover {
  background: var(--accent-light);
  color: var(--accent);
  border-color: var(--accent);
}
.preset-btn.preset-active {
  background: var(--accent);
  color: #ffffff;
  border-color: var(--accent);
}

.btn-text {
  display: inline-block;
  padding: 4px 10px;
  font-size: 0.8125rem;
  color: var(--danger);
  background: none;
  border: none;
  cursor: pointer;
  text-decoration: underline;
  text-underline-offset: 2px;
  transition: color var(--transition);
}
.btn-text:hover {
  color: var(--danger-hover);
}

.btn-open-cf {
  display: inline-flex;
  align-items: center;
  gap: 6px;
  padding: 10px 20px;
  font-size: 0.9375rem;
  font-weight: 600;
  color: #ffffff;
  background: var(--accent);
  border: none;
  border-radius: var(--radius-sm);
  cursor: pointer;
  text-decoration: none;
  transition: background var(--transition);
}
.btn-open-cf:hover {
  background: var(--accent-hover);
}

.btn-roll-again {
  display: inline-flex;
  align-items: center;
  gap: 6px;
  padding: 10px 20px;
  font-size: 0.9375rem;
  font-weight: 600;
  color: var(--accent);
  background: var(--accent-light);
  border: 1px solid var(--accent);
  border-radius: var(--radius-sm);
  cursor: pointer;
  transition: background var(--transition);
}
.btn-roll-again:hover {
  background: #bfdbfe;
}

/* --- 6. Form Inputs --- */
input[type="number"] {
  width: 100px;
  padding: 8px 10px;
  font-size: 0.9375rem;
  font-family: inherit;
  color: var(--text-primary);
  background: var(--bg-secondary);
  border: 1px solid var(--border-color);
  border-radius: var(--radius-sm);
  outline: none;
  transition: border-color var(--transition), box-shadow var(--transition);
}
input[type="number"]:focus {
  border-color: var(--accent);
  box-shadow: 0 0 0 3px rgba(59, 130, 246, 0.15);
}

.tag-search {
  width: 100%;
  max-width: 320px;
  padding: 8px 12px;
  font-size: 0.875rem;
  font-family: inherit;
  color: var(--text-primary);
  background: var(--bg-secondary);
  border: 1px solid var(--border-color);
  border-radius: var(--radius-sm);
  outline: none;
  transition: border-color var(--transition), box-shadow var(--transition);
}
.tag-search:focus {
  border-color: var(--accent);
  box-shadow: 0 0 0 3px rgba(59, 130, 246, 0.15);
}

/* --- 7. Filters Section --- */
.filters {
  background: var(--bg-secondary);
  border: 1px solid var(--border-color);
  border-radius: var(--radius-lg);
  padding: 24px;
  margin-bottom: 24px;
}

.filters h2 {
  font-size: 1.125rem;
  font-weight: 600;
  margin-bottom: 20px;
  color: var(--text-primary);
}

.filter-group {
  margin-bottom: 20px;
}
.filter-group:last-child {
  margin-bottom: 0;
}

.filter-label {
  display: block;
  font-size: 0.875rem;
  font-weight: 600;
  color: var(--text-primary);
  margin-bottom: 8px;
}

.label-hint {
  font-weight: 400;
  color: var(--text-muted);
  font-size: 0.75rem;
}

.rating-presets {
  display: flex;
  flex-wrap: wrap;
  gap: 6px;
  margin-bottom: 12px;
}

.rating-inputs {
  display: flex;
  align-items: center;
  gap: 16px;
  flex-wrap: wrap;
}
.rating-inputs label {
  display: inline-flex;
  align-items: center;
  gap: 6px;
  font-size: 0.875rem;
  font-weight: 500;
  color: var(--text-secondary);
}

/* --- 8. Tag Chips --- */
.tag-container {
  display: flex;
  flex-wrap: wrap;
  gap: 8px;
  margin-bottom: 10px;
  max-height: 280px;
  overflow-y: auto;
  padding: 4px 0;
}

.tag-chip {
  display: inline-block;
  padding: 5px 12px;
  font-size: 0.8125rem;
  font-weight: 500;
  color: var(--chip-text);
  background: var(--chip-bg);
  border: 1px solid transparent;
  border-radius: 20px;
  cursor: pointer;
  user-select: none;
  transition: all var(--transition);
  white-space: nowrap;
}
.tag-chip:hover {
  background: #d0d4da;
}
.tag-chip.selected {
  color: var(--chip-text-selected);
  background: var(--chip-bg-selected);
  border-color: var(--chip-bg-selected);
}
.tag-chip.selected:hover {
  background: var(--accent-hover);
}

/* --- 8.1 Checkboxes --- */
.checkbox-group {
  display: flex;
  flex-direction: column;
  gap: 8px;
}

.checkbox-label {
  display: flex;
  align-items: center;
  gap: 8px;
  font-size: 0.875rem;
  color: var(--text-primary);
  cursor: pointer;
  user-select: none;
}

.checkbox-label input[type="checkbox"] {
  width: 16px;
  height: 16px;
  accent-color: var(--accent);
  cursor: pointer;
  flex-shrink: 0;
}

.checkbox-label strong {
  color: var(--accent);
}

/* --- 9. Problem Count --- */
.problem-count {
  text-align: center;
  font-size: 0.9375rem;
  font-weight: 500;
  color: var(--text-secondary);
  padding: 8px 0;
}
.problem-count .highlight {
  color: var(--accent);
  font-weight: 700;
}

/* --- 10. Roll Section --- */
.roll-section {
  text-align: center;
  margin-bottom: 28px;
}

/* --- 11. Problem Card --- */
.card-section {
  margin-bottom: 28px;
}

.card {
  background: var(--card-bg);
  border: 1px solid var(--border-color);
  border-radius: var(--radius-lg);
  padding: 28px;
  box-shadow: var(--card-shadow);
  animation: fadeInUp 0.35s ease-out;
}

.card-header {
  display: flex;
  align-items: flex-start;
  justify-content: space-between;
  gap: 16px;
  margin-bottom: 12px;
}

.card-id {
  font-family: "JetBrains Mono", "Fira Code", "Consolas", monospace;
  font-size: 0.9375rem;
  font-weight: 600;
  color: var(--text-secondary);
}

.card-title {
  font-size: 1.35rem;
  font-weight: 700;
  color: var(--text-primary);
  line-height: 1.3;
  margin-bottom: 16px;
}

.rating-badge {
  display: inline-block;
  padding: 4px 14px;
  font-size: 1rem;
  font-weight: 700;
  color: #ffffff;
  border-radius: 20px;
  white-space: nowrap;
  flex-shrink: 0;
}

.card-tags {
  display: flex;
  flex-wrap: wrap;
  gap: 6px;
  margin-bottom: 14px;
}
.hide-tags .card-tags {
  display: none;
}

.card-tag {
  display: inline-block;
  padding: 3px 10px;
  font-size: 0.75rem;
  font-weight: 500;
  color: var(--text-secondary);
  background: var(--bg-tertiary);
  border-radius: 14px;
}

.card-solved {
  font-size: 0.875rem;
  color: var(--text-secondary);
  margin-bottom: 20px;
}
.card-you-solved {
  color: #28a745;
  font-weight: 600;
}

.card-actions {
  display: flex;
  align-items: center;
  gap: 12px;
  flex-wrap: wrap;
}

/* --- 12. History --- */
.history-section {
  background: var(--bg-secondary);
  border: 1px solid var(--border-color);
  border-radius: var(--radius-lg);
  padding: 24px;
}

.history-section h2 {
  font-size: 1.125rem;
  font-weight: 600;
  margin-bottom: 14px;
  color: var(--text-primary);
}

.history-item {
  display: flex;
  align-items: center;
  gap: 12px;
  padding: 10px 12px;
  border-radius: var(--radius-sm);
  cursor: pointer;
  transition: background var(--transition);
  flex-wrap: wrap;
}
.history-item:hover {
  background: var(--bg-tertiary);
}
.history-item + .history-item {
  border-top: 1px solid var(--border-color);
}

.history-num {
  font-size: 0.8125rem;
  font-weight: 600;
  color: var(--text-muted);
  min-width: 28px;
}

.history-id {
  font-family: "JetBrains Mono", "Fira Code", "Consolas", monospace;
  font-size: 0.8125rem;
  color: var(--text-secondary);
  min-width: 70px;
}

.history-name {
  font-size: 0.9375rem;
  font-weight: 600;
  color: var(--text-primary);
  flex: 1;
  min-width: 180px;
  overflow: hidden;
  text-overflow: ellipsis;
  white-space: nowrap;
}

.history-rating {
  font-size: 0.8125rem;
  font-weight: 700;
  padding: 2px 10px;
  border-radius: 20px;
  color: #ffffff;
  min-width: 52px;
  text-align: center;
}

.history-tags {
  display: flex;
  flex-wrap: wrap;
  gap: 4px;
}
.hide-tags .history-tags {
  display: none;
}

.history-tag {
  font-size: 0.71875rem;
  color: var(--text-secondary);
  background: var(--bg-tertiary);
  padding: 1px 7px;
  border-radius: 10px;
}

.history-link-icon {
  font-size: 0.875rem;
  color: var(--text-muted);
  flex-shrink: 0;
  opacity: 0;
  transition: opacity var(--transition);
}
.history-item:hover .history-link-icon {
  opacity: 1;
  color: var(--accent);
}

.history-delete {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  width: 22px;
  height: 22px;
  padding: 0;
  font-size: 1rem;
  font-weight: 700;
  line-height: 1;
  color: var(--text-muted);
  background: none;
  border: none;
  border-radius: 50%;
  cursor: pointer;
  flex-shrink: 0;
  opacity: 0;
  transition: opacity var(--transition), color var(--transition), background var(--transition);
}
.history-item:hover .history-delete {
  opacity: 1;
}
.history-delete:hover {
  color: #ffffff;
  background: var(--danger);
}

/* --- 13. Loading Overlay --- */
.loading-overlay {
  display: flex;
  flex-direction: column;
  align-items: center;
  justify-content: center;
  gap: 20px;
  padding: 60px 20px;
  text-align: center;
  color: var(--text-secondary);
  font-size: 1rem;
}

.spinner {
  width: 44px;
  height: 44px;
  border: 4px solid var(--border-color);
  border-top-color: var(--accent);
  border-radius: 50%;
  animation: spin 0.8s linear infinite;
}

/* --- 14. Banners --- */
.banner {
  padding: 12px 18px;
  border-radius: var(--radius-sm);
  font-size: 0.875rem;
  margin-bottom: 16px;
  line-height: 1.5;
}

.banner-info {
  background: var(--info-bg);
  color: var(--info-text);
  border: 1px solid #bee5eb;
}

.banner-error {
  background: var(--error-bg);
  color: var(--error-text);
  border: 1px solid #f5c6cb;
}

.banner-warning {
  background: var(--warning-bg);
  color: var(--warning-text);
  border: 1px solid #ffeeba;
}

.banner .btn-retry {
  display: inline-block;
  margin-left: 8px;
  padding: 4px 12px;
  font-size: 0.8125rem;
  font-weight: 600;
  color: inherit;
  background: rgba(255, 255, 255, 0.4);
  border: 1px solid currentColor;
  border-radius: var(--radius-sm);
  cursor: pointer;
  text-decoration: none;
  transition: background var(--transition);
}
.banner .btn-retry:hover {
  background: rgba(255, 255, 255, 0.6);
}

/* --- 15. Footer --- */
.footer {
  text-align: center;
  padding-top: 32px;
  font-size: 0.8125rem;
  color: var(--text-muted);
}
.footer a {
  color: var(--accent);
  text-decoration: none;
}
.footer a:hover {
  text-decoration: underline;
}

/* --- 16. Utility --- */
.text-muted {
  color: var(--text-muted);
  font-size: 0.9375rem;
  text-align: center;
  padding: 16px 0;
}

/* --- 16. Stats Page --- */

.stats-placeholder {
  text-align: center;
  padding: 80px 20px;
  color: var(--text-muted);
  font-size: 1.0625rem;
}

.stats-loading {
  display: flex;
  flex-direction: column;
  align-items: center;
  gap: 16px;
  padding: 60px 20px;
  color: var(--text-secondary);
}

/* Summary Cards */
.summary-cards {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(180px, 1fr));
  gap: 14px;
  margin-bottom: 24px;
}

.summary-card {
  background: var(--bg-secondary);
  border: 1px solid var(--border-color);
  border-radius: var(--radius-md);
  padding: 18px 16px;
  text-align: center;
}

.summary-card .card-value {
  font-size: 1.75rem;
  font-weight: 700;
  color: var(--accent);
  line-height: 1.2;
}

.summary-card .card-label {
  font-size: 0.8125rem;
  color: var(--text-secondary);
  margin-top: 4px;
}

/* Rating Distribution Chart */
.stats-section {
  background: var(--bg-secondary);
  border: 1px solid var(--border-color);
  border-radius: var(--radius-md);
  padding: 20px 24px;
  margin-bottom: 18px;
}

.stats-section h3 {
  font-size: 1rem;
  font-weight: 600;
  color: var(--text-primary);
  margin-bottom: 16px;
}

.rating-chart {
  display: flex;
  align-items: flex-end;
  gap: 8px;
  height: 180px;
  padding: 0 4px;
}

.rating-bar-wrapper {
  flex: 1;
  display: flex;
  flex-direction: column;
  align-items: center;
  height: 100%;
  justify-content: flex-end;
}

.rating-bar {
  width: 100%;
  max-width: 56px;
  border-radius: 6px 6px 0 0;
  min-height: 4px;
  transition: height 0.6s cubic-bezier(0.4, 0, 0.2, 1);
  position: relative;
}

.tag-dist-bar {
  height: 100%;
  background: var(--accent);
  border-radius: 10px;
  transition: width 0.6s cubic-bezier(0.4, 0, 0.2, 1);
}

.anim-init {
  height: 0 !important;
  width: 0 !important;
}

.rating-bar-count {
  font-size: 0.71875rem;
  font-weight: 700;
  color: var(--text-primary);
  margin-top: 4px;
}

.rating-bar-label {
  font-size: 0.65625rem;
  color: var(--text-secondary);
  margin-top: 2px;
  text-align: center;
  white-space: nowrap;
}

/* Tag Distribution */
.tag-dist-list {
  display: flex;
  flex-direction: column;
  gap: 6px;
}

.tag-dist-item {
  display: flex;
  align-items: center;
  gap: 10px;
}

.tag-dist-name {
  font-size: 0.8125rem;
  font-weight: 500;
  color: var(--text-primary);
  width: 160px;
  flex-shrink: 0;
  text-align: right;
  overflow: hidden;
  text-overflow: ellipsis;
  white-space: nowrap;
}

.tag-dist-bar-wrapper {
  flex: 1;
  height: 20px;
  background: var(--bg-tertiary);
  border-radius: 10px;
  overflow: hidden;
}

.tag-dist-count {
  font-size: 0.8125rem;
  font-weight: 600;
  color: var(--text-secondary);
  min-width: 36px;
}

/* Solved Table */
.solved-table-controls {
  display: flex;
  gap: 10px;
  flex-wrap: wrap;
  margin-bottom: 14px;
}

.solved-table-controls input,
.solved-table-controls select {
  padding: 7px 12px;
  font-size: 0.8125rem;
  font-family: inherit;
  color: var(--text-primary);
  background: var(--bg-primary);
  border: 1px solid var(--border-color);
  border-radius: var(--radius-sm);
  outline: none;
}
.solved-table-controls input:focus,
.solved-table-controls select:focus {
  border-color: var(--accent);
}

.solved-table-controls input {
  flex: 1;
  min-width: 160px;
  max-width: 300px;
}

.solved-table-wrapper {
  overflow-x: auto;
}

.solved-table {
  width: 100%;
  border-collapse: collapse;
  font-size: 0.875rem;
}

.solved-table th {
  text-align: left;
  padding: 10px 12px;
  font-weight: 600;
  color: var(--text-secondary);
  border-bottom: 2px solid var(--border-color);
  white-space: nowrap;
  cursor: pointer;
  user-select: none;
}
.solved-table th:hover {
  color: var(--accent);
}
.solved-table th .sort-arrow {
  font-size: 0.71875rem;
  margin-left: 2px;
}

.solved-table td {
  padding: 8px 12px;
  border-bottom: 1px solid var(--border-color);
  color: var(--text-primary);
  vertical-align: middle;
}

.solved-table tbody tr {
  cursor: pointer;
  transition: background var(--transition);
}
.solved-table tbody tr:hover {
  background: var(--bg-tertiary);
}

.solved-table .st-id {
  font-family: "JetBrains Mono", "Fira Code", "Consolas", monospace;
  font-size: 0.8125rem;
  color: var(--text-secondary);
}

.solved-table .st-rating {
  font-weight: 700;
  padding: 2px 10px;
  border-radius: 20px;
  color: #ffffff;
  font-size: 0.8125rem;
  display: inline-block;
}

.solved-table .st-tags {
  display: flex;
  flex-wrap: wrap;
  gap: 3px;
}

.solved-table .st-tag {
  font-size: 0.6875rem;
  color: var(--text-secondary);
  background: var(--bg-tertiary);
  padding: 2px 8px;
  border-radius: 14px;
  white-space: nowrap;
}

/* --- 16.5 Contests Page --- */

.contests-controls {
  display: flex;
  gap: 10px;
  flex-wrap: wrap;
  margin-bottom: 16px;
}

.contests-search {
  flex: 1;
  min-width: 220px;
  max-width: 400px;
  padding: 8px 12px;
  font-size: 0.875rem;
  font-family: inherit;
  color: var(--text-primary);
  background: var(--bg-secondary);
  border: 1px solid var(--border-color);
  border-radius: var(--radius-sm);
  outline: none;
  transition: border-color var(--transition), box-shadow var(--transition);
}
.contests-search:focus {
  border-color: var(--accent);
  box-shadow: 0 0 0 3px rgba(59, 130, 246, 0.15);
}

.ct-summary {
  font-size: 0.8125rem;
  color: var(--text-secondary);
  margin-bottom: 12px;
}

.ct-contest {
  margin-bottom: 8px;
  border: 1px solid var(--border-color);
  border-radius: var(--radius-md);
  overflow: hidden;
  background: var(--bg-secondary);
}

.ct-header {
  display: flex;
  align-items: center;
  gap: 12px;
  width: 100%;
  padding: 12px 16px;
  font-size: 0.9375rem;
  font-weight: 600;
  color: var(--text-primary);
  background: var(--bg-secondary);
  border: none;
  cursor: pointer;
  text-align: left;
  transition: background var(--transition);
}
.ct-header:hover {
  background: var(--bg-tertiary);
}

.ct-contest-id {
  color: var(--accent);
  font-weight: 700;
  flex: 1;
  min-width: 0;
  overflow: hidden;
  text-overflow: ellipsis;
  white-space: nowrap;
}

.ct-contest-count {
  font-size: 0.8125rem;
  font-weight: 400;
  color: var(--text-secondary);
  flex-shrink: 0;
}

.ct-arrow {
  margin-left: auto;
  font-size: 0.75rem;
  color: var(--text-muted);
  transition: transform 0.2s ease;
}
.ct-header.ct-collapsed .ct-arrow {
  transform: rotate(-90deg);
}

.ct-problems {
  display: flex;
  flex-direction: column;
}
.ct-problems.ct-collapsed {
  display: none;
}

.ct-problem {
  display: flex;
  align-items: center;
  gap: 12px;
  padding: 8px 16px 8px 48px;
  text-decoration: none;
  color: var(--text-primary);
  border-top: 1px solid var(--border-color);
  transition: background var(--transition);
  flex-wrap: wrap;
}
.ct-problem:hover {
  background: var(--accent-light);
}
.ct-problem.ct-solved {
  background: #d4edda;
}
.ct-problem.ct-solved:hover {
  background: #c3e6cb;
}

.ct-index {
  font-family: "JetBrains Mono", "Fira Code", "Consolas", monospace;
  font-size: 0.875rem;
  font-weight: 700;
  color: var(--text-secondary);
  min-width: 24px;
}

.ct-name {
  font-size: 0.875rem;
  font-weight: 500;
  color: var(--text-primary);
  flex: 1;
  min-width: 160px;
  overflow: hidden;
  text-overflow: ellipsis;
  white-space: nowrap;
}

.ct-rating {
  display: inline-block;
  padding: 1px 8px;
  font-size: 0.75rem;
  font-weight: 700;
  color: #ffffff;
  border-radius: 10px;
  min-width: 40px;
  text-align: center;
  flex-shrink: 0;
}

.ct-tags {
  display: flex;
  flex-wrap: wrap;
  gap: 3px;
}
.hide-tags .ct-tags {
  display: none;
}

.ct-tag {
  font-size: 0.6875rem;
  color: var(--text-secondary);
  background: var(--bg-tertiary);
  padding: 1px 6px;
  border-radius: 8px;
  white-space: nowrap;
}

@media (max-width: 768px) {
  .ct-problem {
    padding: 8px 12px 8px 24px;
    gap: 6px;
  }
  .ct-tags {
    display: none;
  }
  .ct-header {
    padding: 10px 12px;
    font-size: 0.875rem;
  }
}

/* --- Contests Pagination --- */
.ct-pagination {
  display: flex;
  align-items: center;
  justify-content: space-between;
  flex-wrap: wrap;
  gap: 10px;
  padding: 14px 0;
  border-top: 1px solid var(--border-color);
}
.ct-pagination:first-child {
  border-top: none;
  border-bottom: 1px solid var(--border-color);
  padding-top: 0;
}

.ct-page-info {
  font-size: 0.8125rem;
  color: var(--text-secondary);
  white-space: nowrap;
}

.ct-page-btns {
  display: flex;
  gap: 4px;
}

.ct-page-btn {
  padding: 5px 12px;
  font-size: 0.8125rem;
  font-weight: 500;
  color: var(--accent);
  background: var(--accent-light);
  border: 1px solid transparent;
  border-radius: var(--radius-sm);
  cursor: pointer;
  transition: background var(--transition), color var(--transition);
}
.ct-page-btn:hover:not(:disabled) {
  background: #bfdbfe;
}
.ct-page-btn:disabled {
  color: var(--text-muted);
  background: var(--bg-tertiary);
  cursor: not-allowed;
}

@media (max-width: 768px) {
  .ct-pagination {
    flex-direction: column;
    align-items: center;
  }
}

/* --- 17. Animations --- */
@keyframes fadeInUp {
  from {
    opacity: 0;
    transform: translateY(16px);
  }
  to {
    opacity: 1;
    transform: translateY(0);
  }
}

@keyframes spin {
  to {
    transform: rotate(360deg);
  }
}

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

.card.just-rolled {
  animation: fadeInUp 0.35s ease-out, pulse 0.3s ease-out 0.05s;
}

/* --- 18. Responsive --- */
@media (max-width: 768px) {
  .container {
    padding: 16px 12px 40px;
  }

  .logo {
    font-size: 1.3rem;
  }

  .header {
    padding-bottom: 14px;
    margin-bottom: 16px;
  }

  .filters {
    padding: 18px 14px;
  }

  .rating-inputs {
    gap: 10px;
  }
  .rating-inputs input[type="number"] {
    width: 80px;
  }

  .btn-roll {
    max-width: 100%;
    padding: 16px 32px;
    font-size: 1.1rem;
  }

  .card {
    padding: 20px 16px;
  }

  .card-title {
    font-size: 1.15rem;
  }

  .card-header {
    flex-direction: column;
    gap: 8px;
  }

  .card-actions {
    flex-direction: column;
    align-items: stretch;
    gap: 8px;
  }
  .card-actions .btn-open-cf,
  .card-actions .btn-roll-again {
    justify-content: center;
  }

  .history-item {
    gap: 8px;
    padding: 8px;
  }
  .history-name {
    min-width: 120px;
    font-size: 0.875rem;
  }
  .history-tags {
    display: none;
  }
}

@media (max-width: 768px) {
  .tab-btn {
    padding: 8px 14px;
    font-size: 0.8125rem;
  }

  .handle-bar {
    padding: 10px 14px;
    gap: 8px;
  }

  .handle-input {
    max-width: 100%;
    flex: 1 1 100%;
  }

  .summary-cards {
    grid-template-columns: repeat(2, 1fr);
    gap: 8px;
  }

  .rating-chart {
    height: 130px;
    gap: 4px;
  }
  .rating-bar-label {
    font-size: 0.5625rem;
  }

  .tag-dist-name {
    min-width: 100px;
    font-size: 0.75rem;
  }

  .solved-table-controls {
    flex-direction: column;
  }
  .solved-table-controls input {
    max-width: 100%;
  }
  .solved-table .st-tags {
    display: none;
  }
}

@media (max-width: 480px) {
  .logo {
    font-size: 1.1rem;
  }

  .btn-icon {
    font-size: 0.75rem;
    padding: 6px 10px;
  }

  .preset-btn {
    font-size: 0.71875rem;
    padding: 5px 10px;
  }

  .rating-presets {
    gap: 4px;
  }

  .tag-container {
    max-height: 200px;
    gap: 5px;
  }

  .tag-chip {
    padding: 4px 10px;
    font-size: 0.71875rem;
  }

  .card-title {
    font-size: 1.05rem;
  }
}