:root {
      /* Surface & Theme Colors */
      --bg-app: #0b1120;
      --bg-card: #1e293b;
      --bg-card-hover: #24344d;
      --bg-input: #0f172a;
      --border-card: #334155;
      --border-input: #475569;
      --border-focus: #3b82f6;

      /* Typography */
      --text-main: #f8fafc;
      --text-muted: #94a3b8;
      --text-dim: #64748b;
      --font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, Helvetica, Arial, sans-serif;
      --font-mono: ui-monospace, SFMono-Regular, Menlo, Monaco, Consolas, monospace;

      /* Brand Accents */
      --color-primary: #3b82f6;
      --color-primary-hover: #2563eb;
      --color-success: #22c55e;
      --color-warning: #f59e0b;
      --color-danger: #ef4444;
      --color-info: #06b6d4;

      /* Board Colors */
      --board-light: #f0d9b5;
      --board-dark: #b58863;
      --board-border: #1e293b;

      /* Radii & Shadows */
      --radius-sm: 0.375rem;
      --radius-md: 0.5rem;
      --radius-lg: 0.75rem;
      --radius-full: 9999px;
      --shadow-card: 0 4px 6px -1px rgba(0, 0, 0, 0.3), 0 2px 4px -2px rgba(0, 0, 0, 0.2);
    }

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

    body {
      font-family: var(--font-family);
      background-color: var(--bg-app);
      color: var(--text-main);
      line-height: 1.5;
      min-height: 100vh;
      padding: 2rem 1rem;
    }

    .app-container {
      max-width: 1140px;
      margin: 0 auto;
    }

    /* Header */
    .app-header {
      display: flex;
      justify-content: space-between;
      align-items: center;
      margin-bottom: 2rem;
      padding-bottom: 1.25rem;
      border-bottom: 1px solid var(--border-card);
      flex-wrap: wrap;
      gap: 1rem;
    }

    .header-brand {
      display: flex;
      align-items: center;
      gap: 0.875rem;
    }

    .brand-icon {
      font-size: 2.5rem;
      line-height: 1;
    }

    .brand-text h1 {
      font-size: 1.625rem;
      font-weight: 700;
      letter-spacing: -0.02em;
    }

    .brand-subtitle {
      color: var(--text-muted);
      font-size: 0.875rem;
    }

    .server-status-pill {
      display: inline-flex;
      align-items: center;
      gap: 0.5rem;
      padding: 0.375rem 0.875rem;
      border-radius: var(--radius-full);
      background-color: rgba(30, 41, 59, 0.8);
      border: 1px solid var(--border-card);
      font-size: 0.8125rem;
      font-weight: 500;
    }

    .status-dot {
      width: 0.625rem;
      height: 0.625rem;
      border-radius: var(--radius-full);
      transition: background-color 0.2s ease, box-shadow 0.2s ease;
    }

    .status-idle { background-color: var(--color-success); box-shadow: 0 0 6px rgba(34, 197, 94, 0.5); }
    .status-running { background-color: var(--color-warning); box-shadow: 0 0 6px rgba(245, 158, 11, 0.5); }
    .status-error { background-color: var(--color-danger); box-shadow: 0 0 6px rgba(239, 68, 68, 0.5); }

    /* Cards */
    .card {
      background-color: var(--bg-card);
      border: 1px solid var(--border-card);
      border-radius: var(--radius-lg);
      padding: 1.5rem;
      box-shadow: var(--shadow-card);
      margin-bottom: 1.75rem;
    }

    .card-title {
      font-size: 1.25rem;
      font-weight: 600;
      margin-bottom: 0.25rem;
      color: var(--text-main);
    }

    .card-subtitle {
      color: var(--text-muted);
      font-size: 0.875rem;
      margin-bottom: 1.25rem;
    }

    .card-header-flex {
      display: flex;
      justify-content: space-between;
      align-items: center;
      margin-bottom: 1.25rem;
      flex-wrap: wrap;
      gap: 0.75rem;
    }

    /* Form Layout */
    .form-row-grid {
      display: grid;
      grid-template-columns: 2fr 1.5fr 1.5fr;
      gap: 1.25rem;
      margin-bottom: 1.25rem;
    }

    @media (max-width: 820px) {
      .form-row-grid { grid-template-columns: 1fr; }
    }

    .form-group {
      display: flex;
      flex-direction: column;
      gap: 0.375rem;
    }

    .form-label {
      font-size: 0.875rem;
      font-weight: 500;
      color: var(--text-main);
    }

    .required { color: var(--color-danger); }

    .form-control {
      background-color: var(--bg-input);
      border: 1px solid var(--border-input);
      border-radius: var(--radius-md);
      color: var(--text-main);
      padding: 0.625rem 0.875rem;
      font-size: 0.9375rem;
      outline: none;
      transition: border-color 0.2s, box-shadow 0.2s;
    }

    .form-control:focus {
      border-color: var(--border-focus);
      box-shadow: 0 0 0 3px rgba(59, 130, 246, 0.25);
    }

    .form-control.is-invalid {
      border-color: var(--color-danger);
      box-shadow: 0 0 0 3px rgba(239, 68, 68, 0.25);
    }

    .form-feedback {
      font-size: 0.75rem;
      color: var(--color-danger);
      min-height: 1rem;
    }

    .form-hint {
      font-size: 0.75rem;
      color: var(--text-dim);
    }

    /* Platform Radio Control */
    .platform-segmented-control {
      display: flex;
      gap: 0.5rem;
    }

    .platform-option {
      flex: 1;
      cursor: pointer;
    }

    .platform-option input {
      position: absolute;
      opacity: 0;
      width: 0;
      height: 0;
    }

    .platform-box {
      display: flex;
      align-items: center;
      justify-content: center;
      gap: 0.5rem;
      background-color: var(--bg-input);
      border: 1px solid var(--border-input);
      border-radius: var(--radius-md);
      padding: 0.625rem 0.75rem;
      font-size: 0.875rem;
      font-weight: 500;
      transition: all 0.2s ease;
      user-select: none;
    }

    .platform-option input:checked + .platform-box {
      border-color: var(--color-primary);
      background-color: rgba(59, 130, 246, 0.15);
      color: #93c5fd;
    }

    /* Tuning Grid */
    .tuning-grid {
      display: grid;
      grid-template-columns: repeat(3, 1fr);
      gap: 1.25rem;
      margin-bottom: 1.25rem;
    }

    @media (max-width: 640px) {
      .tuning-grid { grid-template-columns: 1fr; }
    }

    /* Presets */
    .presets-row {
      display: flex;
      align-items: center;
      gap: 0.5rem;
      margin-bottom: 1.5rem;
      flex-wrap: wrap;
    }

    .presets-label {
      font-size: 0.8125rem;
      color: var(--text-dim);
      font-weight: 500;
    }

    .btn-preset {
      background: none;
      border: 1px solid var(--border-card);
      border-radius: var(--radius-full);
      color: var(--text-muted);
      padding: 0.25rem 0.75rem;
      font-size: 0.75rem;
      cursor: pointer;
      transition: all 0.2s;
    }

    .btn-preset:hover {
      border-color: var(--border-input);
      color: var(--text-main);
      background-color: var(--bg-card-hover);
    }

    .btn-preset.active {
      border-color: var(--color-primary);
      color: #93c5fd;
      background-color: rgba(59, 130, 246, 0.12);
    }

    /* Buttons */
    .form-actions {
      display: flex;
      gap: 0.75rem;
      align-items: center;
    }

    .btn {
      display: inline-flex;
      align-items: center;
      justify-content: center;
      gap: 0.5rem;
      padding: 0.625rem 1.25rem;
      border-radius: var(--radius-md);
      font-size: 0.9375rem;
      font-weight: 600;
      cursor: pointer;
      transition: all 0.2s;
      border: none;
    }

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

    .btn-primary:hover:not(:disabled) {
      background-color: var(--color-primary-hover);
    }

    .btn-secondary {
      background-color: transparent;
      border: 1px solid var(--border-input);
      color: var(--text-muted);
    }

    .btn-secondary:hover:not(:disabled) {
      background-color: var(--bg-card-hover);
      color: var(--text-main);
    }

    .btn-sm {
      padding: 0.25rem 0.625rem;
      font-size: 0.75rem;
    }

    .btn:disabled {
      opacity: 0.6;
      cursor: not-allowed;
    }

    /* Progress & Status Card */
    .progress-card {
      background: linear-gradient(135deg, rgba(30, 41, 59, 0.95), rgba(15, 23, 42, 0.95));
      border: 1px solid rgba(59, 130, 246, 0.3);
    }

    .progress-header {
      display: flex;
      justify-content: space-between;
      align-items: center;
      margin-bottom: 0.5rem;
    }

    .progress-title-wrapper {
      display: flex;
      align-items: center;
      gap: 0.75rem;
    }

    .progress-title {
      font-size: 1.125rem;
      font-weight: 600;
    }

    .progress-timer {
      font-family: var(--font-mono);
      font-size: 0.875rem;
      color: var(--text-muted);
      background-color: var(--bg-input);
      padding: 0.25rem 0.5rem;
      border-radius: var(--radius-sm);
    }

    .progress-description {
      color: var(--text-muted);
      font-size: 0.875rem;
      margin-bottom: 1rem;
    }

    .progress-bar-track {
      width: 100%;
      height: 6px;
      background-color: var(--bg-input);
      border-radius: var(--radius-full);
      overflow: hidden;
      margin-bottom: 1rem;
    }

    .progress-bar-fill.indeterminate {
      width: 40%;
      height: 100%;
      background: linear-gradient(90deg, var(--color-primary), var(--color-info));
      border-radius: var(--radius-full);
      animation: indeterminate 1.8s infinite ease-in-out;
    }

    @keyframes indeterminate {
      0% { transform: translateX(-100%); }
      100% { transform: translateX(350%); }
    }

    .progress-steps-list {
      display: flex;
      gap: 0.75rem;
      flex-wrap: wrap;
    }

    .step-badge {
      font-size: 0.75rem;
      padding: 0.25rem 0.625rem;
      border-radius: var(--radius-full);
      background-color: var(--bg-input);
      color: var(--text-dim);
      border: 1px solid var(--border-card);
    }

    .step-badge.step-active {
      color: #93c5fd;
      border-color: var(--color-primary);
      background-color: rgba(59, 130, 246, 0.15);
    }

    .spinner-circle {
      display: inline-block;
      width: 1.125rem;
      height: 1.125rem;
      border: 2px solid rgba(147, 197, 253, 0.3);
      border-top-color: var(--color-primary);
      border-radius: 50%;
      animation: spin 0.8s linear infinite;
    }

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

    /* Alert / Error Banner */
    .alert {
      display: flex;
      align-items: flex-start;
      gap: 0.875rem;
      padding: 1rem 1.25rem;
      border-radius: var(--radius-lg);
      margin-bottom: 1.75rem;
    }

    .alert-error {
      background-color: rgba(239, 68, 68, 0.12);
      border: 1px solid rgba(239, 68, 68, 0.35);
      color: #fca5a5;
    }

    .alert-heading {
      font-size: 0.9375rem;
      font-weight: 600;
      margin-bottom: 0.25rem;
    }

    .alert-message {
      font-size: 0.875rem;
    }

    /* KPI Metrics Grid */
    .kpi-grid {
      display: grid;
      grid-template-columns: repeat(4, 1fr);
      gap: 1rem;
      margin-bottom: 1.75rem;
    }

    @media (max-width: 768px) {
      .kpi-grid { grid-template-columns: repeat(2, 1fr); }
    }

    .kpi-card {
      background-color: var(--bg-card);
      border: 1px solid var(--border-card);
      border-radius: var(--radius-lg);
      padding: 1rem 1.25rem;
      box-shadow: var(--shadow-card);
    }

    .kpi-label {
      font-size: 0.75rem;
      color: var(--text-muted);
      font-weight: 500;
      text-transform: uppercase;
      letter-spacing: 0.05em;
      margin-bottom: 0.375rem;
    }

    .kpi-value {
      font-size: 1.625rem;
      font-weight: 700;
      color: var(--text-main);
      line-height: 1.2;
    }

    .kpi-value.kpi-danger { color: #f87171; }
    .kpi-value.kpi-highlight { color: #60a5fa; font-size: 1.25rem; }

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

    /* Weakness Table */
    .badge-counter {
      font-size: 0.8125rem;
      background-color: var(--bg-input);
      border: 1px solid var(--border-card);
      padding: 0.25rem 0.625rem;
      border-radius: var(--radius-full);
      color: var(--text-muted);
    }

    .table-responsive {
      overflow-x: auto;
    }

    .weakness-table {
      width: 100%;
      border-collapse: collapse;
      text-align: left;
      font-size: 0.875rem;
    }

    .weakness-table th {
      background-color: var(--bg-input);
      padding: 0.75rem 1rem;
      font-weight: 600;
      color: var(--text-muted);
      border-bottom: 1px solid var(--border-card);
      white-space: nowrap;
    }

    .weakness-table td {
      padding: 0.875rem 1rem;
      border-bottom: 1px solid var(--border-card);
      vertical-align: middle;
    }

    .weakness-table tr:hover td {
      background-color: var(--bg-card-hover);
    }

    .rank-badge {
      display: inline-flex;
      align-items: center;
      justify-content: center;
      width: 1.75rem;
      height: 1.75rem;
      border-radius: 50%;
      font-size: 0.8125rem;
      font-weight: 700;
      background-color: var(--bg-input);
      color: var(--text-muted);
    }

    .rank-1 { background-color: #fef08a; color: #854d0e; }
    .rank-2 { background-color: #e2e8f0; color: #334155; }
    .rank-3 { background-color: #fed7aa; color: #7c2d12; }

    .theme-title-wrapper {
      display: flex;
      flex-direction: column;
      gap: 0.125rem;
    }

    .theme-name {
      font-weight: 600;
      color: var(--text-main);
    }

    .theme-code {
      font-family: var(--font-mono);
      font-size: 0.6875rem;
      color: var(--text-dim);
    }

    .blunder-count-pill {
      display: inline-block;
      padding: 0.2rem 0.5rem;
      border-radius: var(--radius-full);
      background-color: rgba(239, 68, 68, 0.15);
      color: #f87171;
      font-weight: 700;
      font-size: 0.8125rem;
    }

    .freq-cell-wrapper {
      display: flex;
      align-items: center;
      gap: 0.75rem;
    }

    .freq-pct-text {
      width: 3.5rem;
      font-weight: 600;
      font-size: 0.8125rem;
    }

    .freq-bar-bg {
      flex: 1;
      height: 6px;
      background-color: var(--bg-input);
      border-radius: var(--radius-full);
      overflow: hidden;
      min-width: 60px;
    }

    .freq-bar-fill {
      height: 100%;
      background: linear-gradient(90deg, #60a5fa, #3b82f6);
      border-radius: var(--radius-full);
    }

    .delta-badge {
      display: inline-block;
      padding: 0.2rem 0.5rem;
      border-radius: var(--radius-sm);
      font-weight: 600;
      font-family: var(--font-mono);
      font-size: 0.8125rem;
    }

    .delta-severe { background-color: rgba(239, 68, 68, 0.2); color: #f87171; }
    .delta-moderate { background-color: rgba(249, 115, 22, 0.2); color: #fb923c; }
    .delta-mild { background-color: rgba(245, 158, 11, 0.2); color: #fbbf24; }

    .btn-training {
      display: inline-flex;
      align-items: center;
      gap: 0.375rem;
      padding: 0.375rem 0.75rem;
      border-radius: var(--radius-md);
      background-color: rgba(59, 130, 246, 0.15);
      border: 1px solid rgba(59, 130, 246, 0.3);
      color: #93c5fd;
      text-decoration: none;
      font-size: 0.75rem;
      font-weight: 600;
      transition: all 0.2s;
      white-space: nowrap;
    }

    .btn-training:hover {
      background-color: var(--color-primary);
      color: #ffffff;
      border-color: var(--color-primary);
    }

    /* Empty state */
    .empty-state {
      text-align: center;
      padding: 2.5rem 1rem;
    }

    .empty-icon { font-size: 2.5rem; margin-bottom: 0.75rem; }
    .empty-title { font-size: 1.125rem; font-weight: 600; margin-bottom: 0.25rem; }
    .empty-desc { color: var(--text-muted); font-size: 0.875rem; }

    /* Per-Game Breakdown & Accordion */
    .section-header {
      display: flex;
      justify-content: space-between;
      align-items: center;
      flex-wrap: wrap;
      gap: 1rem;
      margin-bottom: 1.25rem;
      padding-bottom: 0.75rem;
      border-bottom: 1px solid var(--border-card);
    }

    .section-title-wrapper {
      display: flex;
      align-items: center;
      gap: 0.75rem;
    }

    .section-title {
      font-size: 1.25rem;
      font-weight: 700;
      margin: 0;
      color: var(--text-main);
    }

    .section-controls {
      display: flex;
      align-items: center;
      gap: 0.75rem;
      flex-wrap: wrap;
    }

    .control-toggle {
      display: flex;
      align-items: center;
      gap: 0.375rem;
      font-size: 0.875rem;
      color: var(--text-muted);
      cursor: pointer;
      user-select: none;
    }

    .accordion-list {
      display: flex;
      flex-direction: column;
      gap: 0.875rem;
    }

    .game-accordion-item {
      border: 1px solid var(--border-card);
      border-radius: var(--radius-md);
      background-color: var(--bg-card);
      overflow: hidden;
      transition: box-shadow 0.15s ease, border-color 0.15s ease;
    }

    .game-accordion-item[open] {
      box-shadow: 0 4px 6px -1px rgba(0, 0, 0, 0.2);
      border-color: var(--border-focus);
    }

    .game-summary {
      display: flex;
      justify-content: space-between;
      align-items: center;
      padding: 0.875rem 1.25rem;
      background-color: var(--bg-card);
      cursor: pointer;
      user-select: none;
      list-style: none;
      gap: 1rem;
      flex-wrap: wrap;
    }

    .game-summary::-webkit-details-marker { display: none; }

    .game-summary:hover {
      background-color: var(--bg-card-hover);
    }

    .summary-left {
      display: flex;
      align-items: center;
      flex-wrap: wrap;
      gap: 0.625rem;
      font-size: 0.9375rem;
      font-weight: 600;
    }

    .player-tag {
      display: inline-flex;
      align-items: center;
      gap: 0.3rem;
    }

    .elo-tag {
      font-weight: 400;
      font-size: 0.8125rem;
      color: var(--text-muted);
    }

    .vs-text {
      font-size: 0.8125rem;
      font-weight: 400;
      color: var(--text-dim);
      text-transform: uppercase;
    }

    .summary-badges {
      display: flex;
      align-items: center;
      flex-wrap: wrap;
      gap: 0.5rem;
    }

    .badge {
      display: inline-flex;
      align-items: center;
      padding: 0.2rem 0.5rem;
      border-radius: 0.25rem;
      font-size: 0.75rem;
      font-weight: 600;
      line-height: 1;
    }

    .badge-neutral {
      background-color: var(--bg-input);
      color: var(--text-muted);
      border: 1px solid var(--border-card);
    }

    .badge-platform {
      background-color: rgba(59, 130, 246, 0.15);
      color: #93c5fd;
      border: 1px solid rgba(59, 130, 246, 0.3);
    }

    .badge-platform-chesscom {
      background-color: rgba(34, 197, 94, 0.15);
      color: #86efac;
      border: 1px solid rgba(34, 197, 94, 0.3);
    }

    .badge-user-white {
      background-color: #f8fafc;
      color: #0f172a;
      border: 1px solid #cbd5e1;
    }

    .badge-user-black {
      background-color: #0f172a;
      color: #f8fafc;
      border: 1px solid #475569;
    }

    .badge-blunder-count {
      background-color: rgba(239, 68, 68, 0.15);
      color: #f87171;
      border: 1px solid rgba(239, 68, 68, 0.35);
    }

    .badge-clean-game {
      background-color: rgba(34, 197, 94, 0.15);
      color: #86efac;
      border: 1px solid rgba(34, 197, 94, 0.35);
    }

    .summary-right {
      display: flex;
      align-items: center;
      gap: 0.75rem;
    }

    .link-game-ext {
      color: var(--color-primary);
      text-decoration: none;
      font-size: 0.8125rem;
      font-weight: 500;
      display: inline-flex;
      align-items: center;
      gap: 0.25rem;
    }

    .link-game-ext:hover {
      text-decoration: underline;
    }

    .accordion-chevron {
      width: 1.25rem;
      height: 1.25rem;
      color: var(--text-muted);
      transition: transform 0.2s ease-in-out;
    }

    .game-accordion-item[open] .accordion-chevron {
      transform: rotate(180deg);
    }

    .game-content {
      padding: 1.25rem;
      border-top: 1px solid var(--border-card);
      background-color: var(--bg-input);
    }

    .clean-game-banner {
      display: flex;
      align-items: center;
      gap: 1rem;
      padding: 1rem 1.25rem;
      background-color: rgba(34, 197, 94, 0.08);
      border: 1px solid rgba(34, 197, 94, 0.25);
      border-radius: var(--radius-md);
      color: #86efac;
    }

    .clean-game-banner h4 {
      font-size: 0.9375rem;
      font-weight: 600;
      margin-bottom: 0.125rem;
    }

    .clean-game-banner p {
      font-size: 0.8125rem;
      color: var(--text-muted);
    }

    /* Blunder Card */
    .blunder-cards-list {
      display: flex;
      flex-direction: column;
      gap: 1.25rem;
    }

    .blunder-card {
      background-color: var(--bg-card);
      border: 1px solid var(--border-card);
      border-radius: var(--radius-md);
      padding: 1.25rem;
      box-shadow: 0 1px 3px rgba(0, 0, 0, 0.2);
    }

    .blunder-card-header {
      display: flex;
      justify-content: space-between;
      align-items: center;
      flex-wrap: wrap;
      gap: 0.75rem;
      margin-bottom: 1rem;
      padding-bottom: 0.625rem;
      border-bottom: 1px solid var(--border-card);
    }

    .blunder-card-title {
      display: flex;
      align-items: center;
      gap: 0.5rem;
      font-size: 0.9375rem;
      font-weight: 600;
    }

    .badge-phase {
      background-color: var(--bg-input);
      color: var(--text-muted);
      border: 1px solid var(--border-card);
      text-transform: capitalize;
    }

    .badge-eval-critical {
      background-color: rgba(239, 68, 68, 0.2);
      color: #f87171;
      border: 1px solid rgba(239, 68, 68, 0.4);
    }

    .badge-eval-severe {
      background-color: rgba(249, 115, 22, 0.2);
      color: #fb923c;
      border: 1px solid rgba(249, 115, 22, 0.4);
    }

    .badge-eval-moderate {
      background-color: rgba(245, 158, 11, 0.2);
      color: #fbbf24;
      border: 1px solid rgba(245, 158, 11, 0.4);
    }

    .move-comparison-grid {
      display: grid;
      grid-template-columns: 1fr 1fr;
      gap: 1rem;
      margin-bottom: 1rem;
    }

    @media (max-width: 600px) {
      .move-comparison-grid { grid-template-columns: 1fr; }
    }

    .move-tile {
      padding: 0.75rem 1rem;
      border-radius: var(--radius-md);
      border: 1px solid var(--border-card);
      background-color: var(--bg-input);
    }

    .move-tile-blunder {
      border-color: rgba(239, 68, 68, 0.35);
      background-color: rgba(239, 68, 68, 0.05);
    }

    .move-tile-best {
      border-color: rgba(34, 197, 94, 0.35);
      background-color: rgba(34, 197, 94, 0.05);
    }

    .move-tile-label {
      font-size: 0.75rem;
      font-weight: 600;
      text-transform: uppercase;
      letter-spacing: 0.05em;
      margin-bottom: 0.25rem;
    }

    .move-tile-blunder .move-tile-label { color: #f87171; }
    .move-tile-best .move-tile-label { color: #4ade80; }

    .move-tile-value {
      font-family: var(--font-mono);
      font-size: 1.125rem;
      font-weight: 700;
      display: block;
      margin-bottom: 0.25rem;
    }

    .move-tile-subtext {
      font-size: 0.75rem;
      color: var(--text-muted);
    }

    .blunder-themes-row {
      display: flex;
      align-items: center;
      flex-wrap: wrap;
      gap: 0.5rem;
      margin-bottom: 1rem;
    }

    .themes-label {
      font-size: 0.8125rem;
      font-weight: 600;
      color: var(--text-muted);
    }

    .theme-chip {
      display: inline-flex;
      align-items: center;
      gap: 0.25rem;
      padding: 0.2rem 0.55rem;
      border-radius: var(--radius-full);
      background-color: rgba(59, 130, 246, 0.15);
      border: 1px solid rgba(59, 130, 246, 0.3);
      color: #93c5fd;
      font-size: 0.75rem;
      font-weight: 500;
      text-decoration: none;
      transition: all 0.15s;
    }

    .theme-chip:hover {
      background-color: var(--color-primary);
      color: #ffffff;
    }

    .theme-fallback {
      background-color: var(--bg-input);
      color: var(--text-muted);
      border-color: var(--border-card);
    }

    .blunder-refutation-row {
      margin-bottom: 1.25rem;
      padding: 0.625rem 0.875rem;
      background-color: var(--bg-input);
      border-radius: var(--radius-md);
      border: 1px solid var(--border-card);
      font-size: 0.8125rem;
    }

    .refutation-label {
      font-weight: 600;
      color: var(--text-main);
      margin-right: 0.5rem;
    }

    .refutation-pv-chips {
      display: inline-flex;
      flex-wrap: wrap;
      gap: 0.375rem;
      margin-top: 0.375rem;
    }

    .pv-move-chip {
      padding: 0.2rem 0.5rem;
      background-color: var(--bg-card);
      border: 1px solid var(--border-card);
      border-radius: var(--radius-sm);
      color: var(--text-main);
      font-family: var(--font-mono);
      font-size: 0.75rem;
      cursor: pointer;
      transition: all 0.15s;
    }

    .pv-move-chip:hover {
      background-color: var(--bg-card-hover);
      border-color: var(--border-input);
    }

    .pv-move-chip.active {
      background-color: #f59e0b;
      color: #000000;
      border-color: #d97706;
      font-weight: 700;
    }

    /* Dual Chess Board Grid */
    .blunder-boards-grid {
      display: grid;
      grid-template-columns: 1fr 1fr;
      gap: 1.5rem;
      margin-top: 1rem;
    }

    @media (max-width: 768px) {
      .blunder-boards-grid { grid-template-columns: 1fr; }
    }

    .board-card {
      display: flex;
      flex-direction: column;
      background-color: var(--bg-input);
      border: 1px solid var(--border-card);
      border-radius: var(--radius-md);
      padding: 0.875rem;
    }

    .board-header {
      display: flex;
      align-items: center;
      justify-content: space-between;
      font-size: 0.8125rem;
      margin-bottom: 0.625rem;
    }

    .board-indicator {
      display: inline-block;
      width: 0.5rem;
      height: 0.5rem;
      border-radius: 9999px;
      margin-right: 0.375rem;
    }

    .dot-green { background-color: var(--color-success); box-shadow: 0 0 4px rgba(34, 197, 94, 0.6); }
    .dot-red { background-color: var(--color-danger); box-shadow: 0 0 4px rgba(239, 68, 68, 0.6); }

    .board-move-hint code {
      font-family: var(--font-mono);
      font-size: 0.75rem;
      padding: 0.1rem 0.35rem;
      border-radius: 0.25rem;
      background-color: var(--bg-card);
      border: 1px solid var(--border-card);
    }

    .board-canvas-wrapper {
      width: 100%;
      aspect-ratio: 1 / 1;
      max-width: 380px;
      margin: 0 auto;
      border-radius: var(--radius-sm);
      overflow: hidden;
      box-shadow: 0 2px 4px rgba(0, 0, 0, 0.3);
      border: 2px solid var(--board-border);
    }

    .chess-board-svg {
      display: block;
      width: 100%;
      height: 100%;
      user-select: none;
    }

    /* PV Stepper Bar */
    .pv-stepper-bar {
      display: flex;
      align-items: center;
      justify-content: space-between;
      margin-top: 0.75rem;
      padding-top: 0.75rem;
      border-top: 1px solid var(--border-card);
      flex-wrap: wrap;
      gap: 0.5rem;
    }

    .stepper-buttons {
      display: flex;
      gap: 0.25rem;
    }

    .btn-step {
      display: inline-flex;
      align-items: center;
      justify-content: center;
      padding: 0.25rem 0.5rem;
      border: 1px solid var(--border-input);
      background-color: var(--bg-card);
      color: var(--text-main);
      border-radius: var(--radius-sm);
      cursor: pointer;
      font-size: 0.75rem;
      font-weight: 600;
      transition: all 0.15s;
    }

    .btn-step:hover {
      background-color: var(--bg-card-hover);
      border-color: var(--color-primary);
    }

    .btn-flip {
      font-size: 0.75rem;
      padding: 0.25rem 0.5rem;
      border-radius: var(--radius-sm);
      background-color: var(--bg-card);
      border: 1px solid var(--border-input);
      color: var(--text-muted);
      cursor: pointer;
    }

    .btn-flip:hover {
      color: var(--text-main);
      border-color: var(--color-primary);
    }

    .step-counter {
      font-size: 0.75rem;
      color: var(--text-muted);
      font-family: var(--font-mono);
    }

    .pv-pills-bar {
      display: flex;
      flex-wrap: wrap;
      gap: 0.3rem;
      margin-top: 0.5rem;
      max-height: 90px;
      overflow-y: auto;
    }

    .pv-pill {
      background-color: var(--bg-card);
      border: 1px solid var(--border-card);
      border-radius: var(--radius-full);
      padding: 0.15rem 0.45rem;
      font-size: 0.7rem;
      font-family: var(--font-mono);
      color: var(--text-muted);
      cursor: pointer;
      transition: all 0.15s;
    }

    .pv-pill:hover {
      border-color: var(--color-primary);
      color: var(--text-main);
    }

    .pv-pill.active {
      background-color: rgba(245, 158, 11, 0.2);
      border-color: #f59e0b;
      color: #fbbf24;
      font-weight: 700;
    }

    /* App Navigation Tabs */
    .app-nav-tabs {
      display: flex;
      gap: 0.5rem;
      margin-bottom: 1.5rem;
      border-bottom: 1px solid var(--border-card);
      padding-bottom: 0.5rem;
    }

    .nav-tab {
      background: transparent;
      border: 1px solid transparent;
      border-radius: var(--radius-md);
      color: var(--text-muted);
      padding: 0.5rem 1rem;
      font-size: 0.95rem;
      font-weight: 600;
      cursor: pointer;
      display: inline-flex;
      align-items: center;
      gap: 0.5rem;
      transition: all 0.2s;
    }

    .nav-tab:hover {
      background: var(--bg-card);
      color: var(--text-main);
    }

    .nav-tab.active {
      background: var(--bg-card);
      border-color: var(--border-card);
      color: var(--color-primary);
    }

    /* Snapshot Banner */
    .snapshot-banner {
      background: rgba(59, 130, 246, 0.15);
      border: 1px solid #3b82f6;
      border-radius: var(--radius-md);
      padding: 0.75rem 1rem;
      margin-bottom: 1.5rem;
      display: flex;
      align-items: center;
      justify-content: space-between;
      gap: 1rem;
    }

    /* Progress Trends & Controls */
    .progress-trends-card {
      margin-top: 1rem;
    }

    .progress-controls-toolbar {
      display: flex;
      align-items: center;
      gap: 0.75rem;
      flex-wrap: wrap;
    }

    .segmented-control {
      display: inline-flex;
      background: var(--bg-input);
      border: 1px solid var(--border-input);
      border-radius: var(--radius-md);
      padding: 2px;
    }

    .segment-btn {
      background: transparent;
      border: none;
      color: var(--text-muted);
      padding: 0.35rem 0.85rem;
      font-size: 0.85rem;
      font-weight: 500;
      border-radius: var(--radius-sm);
      cursor: pointer;
      transition: all 0.15s;
    }

    .segment-btn.active {
      background: var(--color-primary);
      color: #fff;
    }

    .charts-grid {
      display: grid;
      grid-template-columns: repeat(auto-fit, minmax(320px, 1fr));
      gap: 1.25rem;
      margin: 1.5rem 0;
    }

    .chart-card {
      background: var(--bg-input);
      border: 1px solid var(--border-card);
      border-radius: var(--radius-md);
      padding: 1.25rem;
    }

    .chart-header {
      display: flex;
      align-items: center;
      justify-content: space-between;
      margin-bottom: 0.75rem;
    }

    .chart-title {
      font-size: 0.95rem;
      font-weight: 600;
      color: var(--text-main);
    }

    .chart-legend-badge {
      font-size: 0.75rem;
      font-weight: 600;
      padding: 0.2rem 0.5rem;
      border-radius: var(--radius-full);
      background: rgba(59, 130, 246, 0.15);
      color: #60a5fa;
    }

    .chart-svg-container {
      width: 100%;
      min-height: 220px;
      position: relative;
    }

    .chart-svg {
      width: 100%;
      height: 220px;
      overflow: visible;
    }

    .chart-empty {
      display: flex;
      align-items: center;
      justify-content: center;
      height: 200px;
      color: var(--text-dim);
      font-size: 0.9rem;
      font-style: italic;
    }

    .trend-badge {
      display: inline-flex;
      align-items: center;
      gap: 0.25rem;
      padding: 0.2rem 0.55rem;
      border-radius: var(--radius-full);
      font-size: 0.75rem;
      font-weight: 600;
    }

    .trend-improving {
      background: rgba(34, 197, 94, 0.15);
      color: #4ade80;
      border: 1px solid rgba(34, 197, 94, 0.3);
    }

    .trend-degrading {
      background: rgba(239, 68, 68, 0.15);
      color: #f87171;
      border: 1px solid rgba(239, 68, 68, 0.3);
    }

    .trend-stable {
      background: rgba(148, 163, 184, 0.15);
      color: #94a3b8;
      border: 1px solid rgba(148, 163, 184, 0.3);
    }

    /* Authentication & Modal Styles */
    .header-actions {
      display: flex;
      align-items: center;
      gap: 0.75rem;
      flex-wrap: wrap;
    }

    .auth-user-bar {
      display: flex;
      align-items: center;
      gap: 0.5rem;
      background: var(--bg-card);
      border: 1px solid var(--border-card);
      border-radius: var(--radius-full);
      padding: 0.3rem 0.45rem 0.3rem 0.85rem;
    }

    .auth-user-name {
      font-size: 0.85rem;
      font-weight: 600;
      color: var(--text-main);
    }

    .modal-backdrop {
      position: fixed;
      inset: 0;
      background: rgba(2, 6, 23, 0.75);
      backdrop-filter: blur(4px);
      display: flex;
      align-items: center;
      justify-content: center;
      z-index: 1000;
      padding: 1rem;
    }

    .modal-dialog {
      background: var(--bg-card);
      border: 1px solid var(--border-card);
      border-radius: var(--radius-lg);
      box-shadow: var(--shadow-lg);
      width: 100%;
      max-width: 440px;
      padding: 1.5rem;
      position: relative;
    }

    .modal-header {
      display: flex;
      align-items: center;
      justify-content: space-between;
      margin-bottom: 1rem;
    }

    .modal-title {
      font-size: 1.15rem;
      font-weight: 700;
      color: var(--text-main);
      margin: 0;
    }

    .modal-close {
      background: transparent;
      border: none;
      color: var(--text-muted);
      font-size: 1.25rem;
      cursor: pointer;
      padding: 0.25rem 0.5rem;
      border-radius: var(--radius-sm);
    }

    .modal-close:hover {
      color: var(--text-main);
      background: var(--bg-hover);
    }

    .auth-provider-btn {
      display: flex;
      align-items: center;
      justify-content: center;
      gap: 0.65rem;
      width: 100%;
      padding: 0.7rem 1rem;
      border-radius: var(--radius-md);
      border: 1px solid var(--border-card);
      background: var(--bg-input);
      color: var(--text-main);
      font-weight: 600;
      font-size: 0.92rem;
      text-decoration: none;
      transition: all 0.15s ease;
      margin-bottom: 0.65rem;
    }

    .auth-provider-btn:hover {
      background: var(--bg-hover);
      border-color: var(--color-primary);
    }

    .auth-divider {
      display: flex;
      align-items: center;
      gap: 0.75rem;
      color: var(--text-dim);
      font-size: 0.8rem;
      margin: 1rem 0;
    }

    .auth-divider::before,
    .auth-divider::after {
      content: "";
      flex: 1;
      height: 1px;
      background: var(--border-card);
    }

    .sub-list-item {
      display: flex;
      align-items: center;
      justify-content: space-between;
      padding: 0.6rem 0.75rem;
      background: var(--bg-input);
      border: 1px solid var(--border-card);
      border-radius: var(--radius-md);
      margin-bottom: 0.5rem;
      font-size: 0.85rem;
    }