.nd-card {
    --nd-bg: #fff;
    --nd-primary: #6366f1;
    --nd-primary-hover: #4f46e5;
    --nd-border: rgba(99, 102, 241, 0.2);
    --nd-shadow: rgba(99, 102, 241, 0.08);
    --nd-sidebar-bg: rgba(238, 242, 255, 0.5);
    --nd-sidebar-border: rgba(99, 102, 241, 0.15);
    --nd-text: #0f172a;
    --nd-text-muted: #475569;
    --nd-surface: #f8fafc;
    --nd-input-bg: #fff;
    --nd-input-border: rgba(99, 102, 241, 0.3);

    display: flex;
    flex-direction: column;
    background: var(--nd-bg);
    border: 1px solid var(--nd-border);
    border-radius: 1.5rem;
    box-shadow: 0 10px 40px var(--nd-shadow);
    overflow: hidden;
    margin: 2rem 0;
  }

  .theme-dark .nd-card {
    --nd-bg: #18181b;
    --nd-primary: #818cf8;
    --nd-primary-hover: #6366f1;
    --nd-border: rgba(129, 140, 248, 0.2);
    --nd-sidebar-bg: rgba(39, 39, 42, 0.8);
    --nd-sidebar-border: rgba(129, 140, 248, 0.15);
    --nd-text: #f4f4f5;
    --nd-text-muted: #a1a1aa;
    --nd-surface: #27272a;
    --nd-input-bg: #3f3f46;
    --nd-input-border: rgba(129, 140, 248, 0.25);
  }

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

  .nd-heading {
    font-size: 1.1rem;
    font-weight: 700;
    color: var(--nd-text);
    display: flex;
    align-items: center;
    gap: 0.5rem;
  }

  .nd-input-group {
    display: flex;
    flex-direction: column;
    gap: 0.4rem;
  }

  .nd-label {
    font-size: 0.8rem;
    font-weight: 700;
    color: var(--nd-text-muted);
  }

  .nd-input {
    width: 100%;
    padding: 0.6rem 0.75rem;
    border-radius: 0.625rem;
    border: 1px solid var(--nd-input-border);
    background: var(--nd-input-bg);
    color: var(--nd-text);
    font-size: 0.95rem;
    transition: border-color 0.2s;
  }

  .nd-hint-error {
    font-size: 0.75rem;
    color: #ef4444;
  }

  .nd-hidden {
    display: none;
  }

  .nd-mode-toggle {
    display: grid;
    grid-template-columns: 1fr 1fr;
    gap: 0.375rem;
  }

  .nd-mode-btn {
    padding: 0.5rem 0.4rem;
    font-size: 0.75rem;
    font-weight: 600;
    background: var(--nd-surface);
    color: var(--nd-text-muted);
    border: 1px solid var(--nd-input-border);
    border-radius: 0.5rem;
    cursor: pointer;
    transition: background 0.2s, color 0.2s, border-color 0.2s;
    text-align: center;
  }

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

  .nd-main {
    flex: 1;
    padding: 1.5rem;
    display: flex;
    flex-direction: column;
    gap: 1.5rem;
  }

  .nd-result-hero {
    background: rgba(99, 102, 241, 0.06);
    border: 1px solid rgba(99, 102, 241, 0.2);
    border-radius: 1rem;
    padding: 1.25rem 1.5rem;
    display: flex;
    flex-direction: column;
    gap: 0.25rem;
  }

  .nd-result-label {
    font-size: 0.7rem;
    font-weight: 700;
    color: var(--nd-primary);
    text-transform: uppercase;
    letter-spacing: 0.08em;
  }

  .nd-result-value {
    font-size: 2rem;
    font-weight: 800;
    color: var(--nd-primary);
    letter-spacing: -0.02em;
  }

  .nd-z-row {
    display: flex;
    gap: 1.5rem;
    flex-wrap: wrap;
  }

  .nd-z-item {
    display: flex;
    flex-direction: column;
    gap: 0.2rem;
  }

  .nd-z-label {
    font-size: 0.72rem;
    font-weight: 600;
    color: var(--nd-text-muted);
    text-transform: uppercase;
    letter-spacing: 0.04em;
  }

  .nd-z-value {
    font-size: 1.2rem;
    font-weight: 700;
    color: var(--nd-text);
  }

  .nd-chart-section {
    display: flex;
    flex-direction: column;
    gap: 0.5rem;
  }

  .nd-chart-label {
    font-size: 0.9rem;
    font-weight: 700;
    color: var(--nd-text);
  }

  .nd-chart-desc {
    font-size: 0.8rem;
    color: var(--nd-text-muted);
  }

  #nd-chart {
    width: 100%;
    height: 180px;
    display: block;
    border-radius: 0.75rem;
    background: var(--nd-surface);
  }

  .nd-copy-block {
    background: rgba(99, 102, 241, 0.06);
    border: 1px solid rgba(99, 102, 241, 0.25);
    border-radius: 1rem;
    padding: 1rem 1.25rem;
    display: flex;
    flex-direction: column;
    gap: 0.75rem;
  }

  .nd-copy-header {
    font-size: 0.75rem;
    font-weight: 700;
    color: var(--nd-primary);
    text-transform: uppercase;
    letter-spacing: 0.06em;
  }

  .nd-copy-text {
    font-size: 0.85rem;
    color: var(--nd-text);
    line-height: 1.6;
    background: var(--nd-input-bg);
    border: 1px solid var(--nd-input-border);
    border-radius: 0.5rem;
    padding: 0.625rem 0.75rem;
    min-height: 2.25rem;
    margin: 0;
    word-break: break-all;
  }

  .nd-copy-btn {
    align-self: flex-start;
    padding: 0.5rem 1.25rem;
    background: var(--nd-primary);
    color: #fff;
    border: none;
    border-radius: 0.5rem;
    font-weight: 700;
    font-size: 0.875rem;
    cursor: pointer;
    transition: background 0.2s;
  }

  .nd-copy-btn:hover {
    background: var(--nd-primary-hover);
  }

  @media (min-width: 768px) {
    .nd-card {
      flex-direction: row;
    }

    .nd-sidebar {
      width: 280px;
      flex-shrink: 0;
      border-bottom: none;
      border-right: 1px solid var(--nd-sidebar-border);
    }
  }