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@JasonWeill
I'm not sure if JupyterLab is participating in Hacktoberfest this year, but if possible, could this PR be labeled as 'hacktoberfest-accepted'? I would greatly appreciate it!

@Darshan808 I can ask about this at our next regular meeting. Thanks for opening this!

I see no perceptible difference with this change, compared with 4.2.5, on macOS and Firefox.

@JasonWeill
The issue with hidden underscores occurs specifically with the 'Ubuntu' font, the default in Ubuntu OS. So far, I haven't encountered this problem with any other fonts I've tested.
The reason you may not have seen any visible changes is likely due to how different fonts handle line-height. For example, setting line-height: 1.2 has a more noticeable effect with the 'Ubuntu' font compared to others like 'Poppins'.
Also this change provides consistent spacing without negatively affecting readability or design. It's a minimal adjustment that prevents issues with the 'Ubuntu' font while maintaining a clean look across different fonts.

@Darshan808 I can ask about this at our next regular meeting. Thanks for opening this!
@JasonWeill Could you please update me on the outcome of the meeting regarding this?

@Darshan808 Jupyter projects are not part of Hacktoberfest this year, but we still welcome your contributions. Thanks again!

I tried to reproduce the error using 4.2.5 (dev), 4.3.0a2 (app) on Linux Mint (a derivative of Ubuntu). I am unable to reproduce it after pulling the branch and removing line 319 : line-height: 1.2; in /packages/filebrowser/style/base.css

I changed the line height to different values, and the underscore remains. Also tested changing the browser resolution from 100% with no impact on the display.

This appears to be a niche issue that is not originating from Jupyter Lab but a specific version of Ubuntu, and may be automatically handled in new releases of Jupyter Lab.

I would recommend leaving it untouched for now, given that changing the line height affects the display on all systems that are unaffected, which is mostly all. This is already suggested here: #16820 (comment)
Visually, increasing the line height to 1.2 leaves a little bit more spacing between items and (IMHO) impairs the visual look and feel in addition to losing some valuable real estate in the file browser.

I was able to reproduce the original issue on the latest Ubuntu. I do not recall what browser it was with and if only certain zoom sizes were affected. I recall it only started in the latest Ubuntu release so Mint may not be affected yet

This is not JupyterLab specific though see for example microsoft/vscode#227583

I added more context in #16820 (comment)

@Darshan808 it looks like this PR was opened against 4.2.x branch rather than master. Can you change the target branch?

@Darshan808 it looks like this PR was opened against 4.2.x branch rather than master. Can you change the target branch?
Oh, that was a silly mistake! I've changed the target branch now—done!

@Darshan808 @krassowski Issue #16820 was noted as occurring only in 4.2.x and not in the 4.3.0 beta, so I think the merge into the 4.2.x branch was intended. See @Darshan808 's comment here: #16820 (comment)

Oh, I overlooked that. Yes, the PR was intended to be created in the 4.2.x branch.