.pc-card {
    --pc-bg: rgba(255, 255, 255, 0.7);
    --pc-border: rgba(99, 102, 241, 0.15);
    --pc-shadow: rgba(0, 0, 0, 0.08);
    --pc-sidebar-bg: rgba(99, 102, 241, 0.03);
    --pc-sidebar-border: rgba(99, 102, 241, 0.1);
    --pc-primary: #6366f1;
    --pc-accent: #ec4899;
    --pc-text: #1e293b;
    --pc-text-muted: #64748b;
    --pc-text-label: #64748b;
    --pc-input-bg: #fff;
    --pc-input-border: #e2e8f0;
    --pc-input-border-focus: #6366f1;
    --pc-surface: rgba(255, 255, 255, 0.5);
    --pc-surface-border: rgba(99, 102, 241, 0.05);
    --pc-icon-btn-bg: #fff;
    --pc-icon-btn-border: #e2e8f0;
    --pc-icon-btn-color: #64748b;
    --pc-stat-value: #1e293b;
    --pc-actions-border: rgba(99, 102, 241, 0.1);
    --pc-main-stat-border: rgba(99, 102, 241, 0.1);
    --pc-privacy-color: #94a3b8;
    --pc-privacy-border: rgba(99, 102, 241, 0.1);
    --pc-error-bg: rgba(255, 255, 255, 0.9);
    --pc-error-color: #ef4444;

    background: var(--pc-bg);
    backdrop-filter: blur(12px);
    border-radius: 2rem;
    border: 1px solid var(--pc-border);
    box-shadow: 0 20px 40px -15px var(--pc-shadow);
    max-width: 1100px;
    margin: 0 auto;
    overflow: hidden;
    display: grid;
    grid-template-columns: 350px 1fr;
    min-height: 600px;
  }

  .theme-dark .pc-card {
    --pc-bg: rgba(24, 24, 27, 0.95);
    --pc-border: rgba(99, 102, 241, 0.2);
    --pc-shadow: rgba(0, 0, 0, 0.3);
    --pc-sidebar-bg: rgba(99, 102, 241, 0.04);
    --pc-sidebar-border: rgba(255, 255, 255, 0.05);
    --pc-primary: #818cf8;
    --pc-accent: #f472b6;
    --pc-text: #f1f5f9;
    --pc-text-muted: #94a3b8;
    --pc-text-label: #94a3b8;
    --pc-input-bg: #0f172a;
    --pc-input-border: #334155;
    --pc-input-border-focus: #818cf8;
    --pc-surface: rgba(15, 23, 42, 0.3);
    --pc-surface-border: rgba(99, 102, 241, 0.08);
    --pc-icon-btn-bg: #1e293b;
    --pc-icon-btn-border: #334155;
    --pc-icon-btn-color: #94a3b8;
    --pc-stat-value: #f1f5f9;
    --pc-actions-border: rgba(99, 102, 241, 0.15);
    --pc-main-stat-border: rgba(99, 102, 241, 0.15);
    --pc-privacy-color: #475569;
    --pc-privacy-border: rgba(255, 255, 255, 0.05);
    --pc-error-bg: rgba(15, 23, 42, 0.9);
    --pc-error-color: #f87171;
  }

  .pc-sidebar {
    background: var(--pc-sidebar-bg);
    border-right: 1px solid var(--pc-sidebar-border);
    padding: 2rem;
    display: flex;
    flex-direction: column;
    gap: 1.5rem;
  }

  .pc-sidebar-header {
    display: flex;
    justify-content: space-between;
    align-items: center;
  }

  .pc-sidebar-title {
    margin: 0;
    font-size: 1.1rem;
    font-weight: 700;
    color: var(--pc-primary);
    display: flex;
    align-items: center;
    gap: 0.5rem;
  }

  .pc-textarea {
    flex: 1;
    width: 100%;
    min-height: 300px;
    background: var(--pc-input-bg);
    border: 2px solid var(--pc-input-border);
    border-radius: 1rem;
    padding: 1rem;
    font-size: 0.875rem;
    resize: none;
    transition: all 0.2s ease;
    color: var(--pc-text);
    box-sizing: border-box;
  }

  .pc-textarea:focus {
    outline: none;
    border-color: var(--pc-input-border-focus);
    box-shadow: 0 0 0 3px rgba(99, 102, 241, 0.1);
  }

  .pc-setting-row {
    display: flex;
    align-items: center;
    justify-content: space-between;
    gap: 0.5rem;
  }

  .pc-setting-label {
    font-size: 0.75rem;
    font-weight: 700;
    color: var(--pc-text-label);
    text-transform: uppercase;
  }

  .pc-setting-select {
    padding: 0.25rem 0.5rem;
    border-radius: 0.5rem;
    border: 1px solid var(--pc-input-border);
    font-size: 0.75rem;
    background: var(--pc-input-bg);
    color: var(--pc-text);
    cursor: pointer;
  }

  .pc-privacy-badge {
    margin-top: auto;
    padding-top: 1rem;
    border-top: 1px dashed var(--pc-privacy-border);
    font-size: 0.7rem;
    color: var(--pc-privacy-color);
    display: flex;
    align-items: center;
    gap: 0.5rem;
  }

  .pc-main {
    padding: 2rem;
    display: flex;
    flex-direction: column;
    gap: 2rem;
  }

  .pc-results-top {
    display: grid;
    grid-template-columns: auto 1fr;
    gap: 2rem;
    align-items: center;
  }

  .pc-main-stat {
    display: flex;
    flex-direction: column;
    align-items: center;
    justify-content: center;
    padding-right: 2rem;
    border-right: 2px solid var(--pc-main-stat-border);
    min-width: 200px;
  }

  .pc-r-value {
    font-size: 4rem;
    font-weight: 950;
    letter-spacing: -2px;
    line-height: 1;
    background: linear-gradient(135deg, #6366f1, #ec4899);
    -webkit-background-clip: text;
    background-clip: text;
    -webkit-text-fill-color: transparent;
    text-align: center;
    width: 100%;
  }

  .pc-r-label {
    font-size: 0.75rem;
    text-transform: uppercase;
    font-weight: 800;
    color: var(--pc-text-muted);
    margin-top: 0.5rem;
  }

  .pc-stats-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(140px, 1fr));
    gap: 1.5rem;
  }

  .pc-stat-group {
    display: flex;
    flex-direction: column;
  }

  .pc-stat-label {
    font-size: 0.7rem;
    color: var(--pc-text-label);
    font-weight: 600;
    text-transform: uppercase;
    margin-bottom: 0.25rem;
  }

  .pc-stat-value {
    font-size: 1.25rem;
    font-weight: 800;
    color: var(--pc-stat-value);
  }

  .pc-stat-block .pc-stat-means { font-size: 1rem; }

  .pc-canvas-wrap {
    background: var(--pc-surface);
    border: 1px solid var(--pc-surface-border);
    border-radius: 1.5rem;
    padding: 1rem;
    position: relative;
    overflow: hidden;
  }

  #scatter-plot {
    display: block;
    width: 100%;
    height: 280px;
  }

  .pc-error-overlay {
    position: absolute;
    inset: 0;
    background: var(--pc-error-bg);
    flex-direction: column;
    align-items: center;
    justify-content: center;
    border-radius: 1.5rem;
    color: var(--pc-error-color);
    font-weight: 600;
    font-size: 0.85rem;
    text-align: center;
    padding: 2rem;
    gap: 0.75rem;
  }

  .pc-actions-row {
    display: flex;
    justify-content: space-between;
    align-items: center;
    border-top: 1px solid var(--pc-actions-border);
    padding-top: 1.5rem;
  }

  .pc-interp-badge {
    padding: 0.5rem 1.25rem;
    border-radius: 100px;
    font-weight: 700;
    font-size: 0.85rem;
    background: rgba(99, 102, 241, 0.05);
    color: var(--pc-text-muted);
  }

  .pc-interp-strong {
    background: #dcfce7;
    color: #166534;
  }

  .theme-dark .pc-interp-strong {
    background: rgba(22, 163, 74, 0.15);
    color: #86efac;
  }

  .pc-interp-moderate {
    background: #fef9c3;
    color: #854d0e;
  }

  .theme-dark .pc-interp-moderate {
    background: rgba(202, 138, 4, 0.15);
    color: #fde047;
  }

  .pc-interp-weak {
    background: #f1f5f9;
    color: #475569;
  }

  .theme-dark .pc-interp-weak {
    background: #27272a;
    color: #a1a1aa;
  }

  .pc-btn-group {
    display: flex;
    gap: 0.5rem;
    align-items: center;
  }

  .pc-regression-eq {
    font-size: 0.75rem;
    color: var(--pc-text-muted);
    margin-right: 1rem;
  }

  .pc-icon-btn {
    width: 40px;
    height: 40px;
    display: flex;
    align-items: center;
    justify-content: center;
    border-radius: 12px;
    background: var(--pc-icon-btn-bg);
    border: 1px solid var(--pc-icon-btn-border);
    color: var(--pc-icon-btn-color);
    cursor: pointer;
    transition: all 0.2s cubic-bezier(0.4, 0, 0.2, 1);
  }

  .pc-icon-btn:hover {
    transform: translateY(-2px);
    border-color: var(--pc-primary);
    color: var(--pc-primary);
  }

  .pc-main > *,
  .pc-sidebar > * { min-width: 0; }

  @media (max-width: 900px) {
    .pc-card { grid-template-columns: 1fr; }
    .pc-sidebar {
      border-right: none;
      border-bottom: 1px solid var(--pc-sidebar-border);
      padding: 1.5rem;
    }
    .pc-textarea { min-height: 150px; }
  }

  @media (max-width: 600px) {
    .pc-card {
      border-radius: 1rem;
      margin: 0;
    }
    .pc-sidebar { padding: 1.25rem; }
    .pc-main {
      padding: 1.25rem;
      gap: 1.25rem;
    }
    .pc-results-top {
      grid-template-columns: 1fr;
      gap: 1rem;
    }
    .pc-main-stat {
      border-right: none;
      border-bottom: 2px solid var(--pc-main-stat-border);
      padding-right: 0;
      padding-bottom: 1rem;
      min-width: unset;
    }
    .pc-r-value {
      font-size: 2.5rem;
      letter-spacing: -1px;
    }
    .pc-stats-grid {
      grid-template-columns: repeat(2, 1fr);
      gap: 1rem;
    }
    .pc-actions-row {
      flex-direction: column;
      gap: 0.75rem;
      align-items: flex-start;
    }
    .pc-interp-badge {
      font-size: 0.8rem;
      padding: 0.4rem 1rem;
    }
    .pc-canvas-wrap { border-radius: 1rem; }
    #scatter-plot { height: 200px; }
  }