Telescopetest-io: metrics tab navtiming entries overlap when browser has increased font size

## Describe the bug

If user's Chromium browser's baseline font size and zoom level are different ("Medium" & 125% in my case), the timestamp labels overlay with each other.

Exact configuration that causes it is unclear.

## Steps to reproduce

Change browser settings, open metrics tab and look at the navigation timing diagram, click "clear filters" button to show all markers.

## Expected results

Each timestamp name and their value are on their distinct lines without any vertical overlap.

## Observed results

Timestamp overlaps with the value from another timestamp, but distance between timestamp and it's own value is correct. See screenshot.

## Additional context