sidebar options in settings UI doesn't have bottom border

[simonhong]

As captured below, sidebar options has redundant top border and bottom border is missed.
It should have bottom border only.

STR

1. Enable sidebar flags
2. Load brave://settings/?search=sidebar
3. Check Sidebar options border

[stephendonner]

Verified PASSED using

Brave	1.37.50 Chromium: 98.0.4758.87 (Official Build) nightly (64-bit)
Revision	e4cd00f135fb4d8edc64c8aa6ecbe7cc79ebb3b2-refs/branch-heads/4758@{#1002}
OS	Windows 10 Version 21H2 (Build 19044.1526)

Steps:

1. install 1.37.50
2. launch Brave
3. enabled Sidebar via brave://flags
4. clicked to Relaunch
5. loaded brave://settings/appearance
6. confirmed the Settings UI now has the correct top/bottom border for Show Sidebar

pre-fix	post-fix

[btlechowski]

Verification passed on

Brave	1.37.83 Chromium: 99.0.4844.51 (Official Build) beta (64-bit)
Revision	d537ec02474b5afe23684e7963d538896c63ac77-refs/branch-heads/4844@{#875}
OS	Ubuntu 18.04 LTS

[stephendonner]

Verified PASSED using

Brave	1.37.91 Chromium: 99.0.4844.51 (Official Build) beta (x86_64)
Revision	d537ec02474b5afe23684e7963d538896c63ac77-refs/branch-heads/4844@{#875}
OS	macOS Version 12.3 (Build 21E230)

dark	light