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

  body {
    overflow: hidden;
    display: flex;
    flex-direction: column;
    height: 100vh;
  }

  /* ---- Toolbar ---- */
  .toolbar {
    display: flex;
    align-items: center;
    padding: 3px 4px;
    gap: 3px;
    background: var(--sz-color-button-face);
    border-bottom: 1px solid var(--sz-color-button-shadow);
    flex-shrink: 0;
    user-select: none;
    flex-wrap: wrap;
  }

  .toolbar button {
    padding: 2px 8px;
    font-size: 11px;
    font-family: Tahoma, Verdana, sans-serif;
    cursor: default;
    white-space: nowrap;
  }

  .toolbar button.active {
    border-style: inset;
    background: var(--sz-color-highlight);
    color: var(--sz-color-highlight-text);
  }

  .toolbar button:disabled {
    color: var(--sz-color-gray-text);
    pointer-events: none;
  }

  .toolbar-sep {
    width: 1px;
    height: 20px;
    background: var(--sz-color-button-shadow);
    margin: 0 3px;
    flex-shrink: 0;
  }

  .toolbar .stats {
    margin-left: auto;
    font-size: 10px;
    color: var(--sz-color-button-text);
    white-space: nowrap;
    padding: 0 4px;
  }

  /* Intentional diff stat colors */
  .stats .stat-add { color: #1a7f37; font-weight: bold; }
  .stats .stat-del { color: #cf222e; font-weight: bold; }
  .stats .stat-mod { color: #9a6700; font-weight: bold; }
  .stats .stat-eq  { color: var(--sz-color-gray-text); }

  /* ---- Options bar ---- */
  .options-bar {
    display: flex;
    align-items: center;
    padding: 2px 6px;
    gap: 12px;
    background: var(--sz-color-button-face);
    border-bottom: 1px solid var(--sz-color-button-shadow);
    flex-shrink: 0;
    user-select: none;
    font-size: 11px;
  }

  .options-bar label {
    display: flex;
    align-items: center;
    gap: 3px;
    cursor: default;
    color: var(--sz-color-button-text);
  }

  /* ---- Main content area ---- */
  .main-area {
    flex: 1;
    display: flex;
    overflow: hidden;
    position: relative;
  }

  /* ---- Side-by-side panels ---- */
  .panel {
    flex: 1;
    display: flex;
    flex-direction: column;
    overflow: hidden;
    min-width: 0;
  }

  .panel-header {
    padding: 3px 8px;
    background: var(--sz-color-button-face);
    border-bottom: 1px solid var(--sz-color-button-shadow);
    font-weight: bold;
    font-size: 11px;
    color: var(--sz-color-button-text);
    user-select: none;
    flex-shrink: 0;
  }

  .panel-splitter {
    width: 4px;
    background: var(--sz-color-button-face);
    border-left: 1px solid var(--sz-color-button-shadow);
    border-right: 1px solid var(--sz-color-button-shadow);
    cursor: col-resize;
    flex-shrink: 0;
  }

  .panel-content {
    flex: 1;
    overflow: auto;
    background: var(--sz-color-window);
    font-family: 'Consolas', 'Lucida Console', 'Courier New', monospace;
    font-size: 12px;
    line-height: 18px;
    position: relative;
  }

  /* ---- Text input areas (when editable) ---- */
  .panel-textarea {
    width: 100%;
    height: 100%;
    border: none;
    outline: none;
    resize: none;
    font-family: 'Consolas', 'Lucida Console', 'Courier New', monospace;
    font-size: 12px;
    line-height: 18px;
    padding: 4px 8px;
    background: var(--sz-color-window);
    color: var(--sz-color-window-text);
    tab-size: 4;
  }

  /* ---- Diff lines ---- */
  .diff-table {
    width: 100%;
    border-collapse: collapse;
  }

  .diff-line {
    display: flex;
    min-height: 18px;
  }

  .line-gutter {
    flex-shrink: 0;
    width: 16px;
    text-align: center;
    font-size: 11px;
    color: var(--sz-color-gray-text);
    user-select: none;
    border-right: 1px solid var(--sz-color-button-shadow);
  }

  .line-number {
    flex-shrink: 0;
    width: 48px;
    text-align: right;
    padding-right: 6px;
    font-size: 11px;
    color: var(--sz-color-gray-text);
    user-select: none;
    border-right: 1px solid var(--sz-color-button-shadow);
  }

  .line-text {
    flex: 1;
    padding: 0 6px;
    white-space: pre;
    min-width: 0;
    overflow: hidden;
    color: var(--sz-color-window-text);
  }

  /* Side-by-side diff colors -- intentional diff semantic colors */
  .diff-line.added {
    background: #e6ffec;
  }

  .diff-line.added .line-gutter {
    background: #ccffd8;
    color: #1a7f37;
  }

  .diff-line.deleted {
    background: #ffebe9;
  }

  .diff-line.deleted .line-gutter {
    background: #ffd7d5;
    color: #cf222e;
  }

  .diff-line.modified {
    background: #fff8c5;
  }

  .diff-line.modified .line-gutter {
    background: #fff2a8;
    color: #9a6700;
  }

  .diff-line.empty-placeholder {
    background: #f6f8fa;
  }

  .diff-line.empty-placeholder .line-text {
    color: transparent;
  }

  /* Character-level highlights -- intentional diff colors */
  .char-add {
    background: #abf2bc;
    border-radius: 2px;
  }

  .char-del {
    background: #ffc1ba;
    border-radius: 2px;
  }

  .char-mod {
    background: #ffe17e;
    border-radius: 2px;
  }

  /* Unified view colors -- intentional diff colors */
  .diff-line.unified-add {
    background: #e6ffec;
  }

  .diff-line.unified-add .line-gutter {
    background: #ccffd8;
    color: #1a7f37;
  }

  .diff-line.unified-del {
    background: #ffebe9;
  }

  .diff-line.unified-del .line-gutter {
    background: #ffd7d5;
    color: #cf222e;
  }

  .diff-line.unified-ctx {
    background: var(--sz-color-window);
  }

  .diff-line.hunk-header {
    background: #ddf4ff;
    color: #0969da;
    font-style: italic;
  }

  .diff-line.hunk-header .line-text {
    color: #0969da;
  }

  /* Inline view -- intentional diff colors */
  .inline-del {
    background: #ffc1ba;
    text-decoration: line-through;
    color: #cf222e;
  }

  .inline-add {
    background: #abf2bc;
    color: #1a7f37;
  }

  /* ---- Current diff highlight ---- */
  .diff-line.current-diff {
    outline: 2px solid var(--sz-color-highlight);
    outline-offset: -2px;
  }

  /* ---- Unified panel (single) ---- */
  .unified-panel {
    flex: 1;
    display: flex;
    flex-direction: column;
    overflow: hidden;
  }

  .unified-panel .panel-content {
    flex: 1;
  }

  /* ---- Status bar ---- */
  .status-bar {
    display: flex;
    align-items: center;
    padding: 2px 8px;
    background: var(--sz-color-button-face);
    border-top: 1px solid var(--sz-color-button-shadow);
    font-size: 11px;
    color: var(--sz-color-button-text);
    flex-shrink: 0;
    user-select: none;
    gap: 16px;
  }

  .status-bar .status-section {
    white-space: nowrap;
  }

  /* ---- Empty / placeholder ---- */
  .empty-state {
    display: flex;
    align-items: center;
    justify-content: center;
    height: 100%;
    color: var(--sz-color-gray-text);
    font-size: 12px;
    font-style: italic;
    font-family: Tahoma, Verdana, sans-serif;
    text-align: center;
    padding: 20px;
  }