opencode/packages/session-ui/src/components/file.css

[data-component="file"] {
  content-visibility: auto;
}

[data-timeline-row] [data-component="file"] {
  content-visibility: visible;
}

[data-component="file"][data-mode="text"] {
  overflow: hidden;
}

[data-component="file"][data-mode="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(--diffs-column-content-width);
    left: var(--diffs-column-number-width);
    padding-left: 8px;
    user-select: none;
    cursor: default;
    text-align: left;

    [data-slot="diff-hunk-separator-content-span"] {
      mix-blend-mode: var(--text-mix-blend-mode);
    }
  }
}