Vertical separators missing in header row.

## Describe the bug

Vertical separators are sometimes missing in header row, this is in chrome only.


## To Reproduce

1. In Chrome, shrink first few columns to their minimum size.
- The grid must still be wide enough to require horizontal scrolling.
2. Observe the missing header column borders.

## Expected behavior

Header separators should never disappear, no matter the zoom level, column sizes, or if horizontal scrolling is required.

## Link to Minimal Reproducible Example

https://adazzle.github.io/react-data-grid/#/CommonFeatures

## Environment

- `react-data-grid` version: 7.0.0-beta-52 and earlier.
- `react`/`react-dom` version: 19.1.0 and earlier.

## Additional context

Here's a screen recording of the behavior.

https://github.com/user-attachments/assets/d9708f67-7fdd-429d-9f29-d66235a9e6ca

I noticed this comment in the stylesheet
```css
.cj343x07-0-0-beta-52 {
@layer rdg.Cell {
/* max-content does not work with size containment
* dynamically switching between different containment styles incurs a heavy relayout penalty
* Chromium bug: at odd zoom levels or subpixel positioning,
* layout/paint/style containment can make cell borders disappear
* https://issues.chromium.org/issues/40840864
*/
position: relative; /* needed for absolute positioning to work */
padding-block: 0;
padding-inline: 8px;
border-inline-end: 1px solid var(--rdg-border-color);
border-block-end: 1px solid var(--rdg-border-color);
grid-row-start: var(--rdg-grid-row-start);
align-content: center;
background-color: inherit;

white-space: nowrap;
overflow: clip;
text-overflow: ellipsis;
outline: none;

&[aria-selected='true'] {
outline: 2px solid var(--rdg-selection-color);
outline-offset: -2px;
}
}
}
```

but this is occurring at 100% zoom.

Unfortunately, removing `contain: content` from the `rdg.Root` styles as the comment above would suggest, does not resolve the issue.

Removing `sticky` from the `rdg.HeaderRow` styles allows the `position: relative` in the `rdg.Cell` styles to be applied, fixing the issue, but losing sticky header columns not an acceptable workaround.