Description

Left side border is thicker than others as it has additional space when vertical tab is hidden completely.
That space is used for detecting mouse hover event for expanding vertical tab.

w/o rounded corners, it's more worse.

Steps to reproduce

1. Enable vertical tab and check Hide completely when minimized option from brave://settings/appearance
2. Enable Show rounded corners on main content area

Actual result

Vertical tab side window border is thicker than others

Expected result

Same border width

Reproduces how often

Easily reproduced

Brave version (brave://version info)

1.87.6 Chromium: 143.0.7499.40 (Official Build) nightly (arm64)

Channel information

• release (stable)
• beta
• nightly

Reproducibility

• with Brave Shields disabled
• with Brave Rewards disabled
• in the latest version of Chrome

Miscellaneous information

cc @rebron @brave/legacy_qa @aguscruiz @sangwoo108