opencode-ide-plugin/packages/ui/src/components/diff.css

[data-component="diff"] {
  [data-slot="diff-hunk-separator-line-number"] {
    position: sticky;
    left: 0;
    background-color: var(--surface-diff-hidden-strong);
    z-index: 2;
    display: flex;
    align-items: center;
    justify-content: center;

    [data-slot="diff-hunk-separator-line-number-icon"] {
      aspect-ratio: 1;
      width: 24px;
      height: 24px;
      color: var(--icon-strong-base);
    }
  }
  [data-slot="diff-hunk-separator-content"] {
    position: sticky;
    background-color: var(--surface-diff-hidden-base);
    color: var(--text-base);
    width: var(--pjs-column-content-width);
    left: var(--pjs-column-number-width);
    padding-left: 8px;
  }
}