Tweak the style for deleted flags table

[zhouzhuojie]

Description

• Tweak a little bit of the style of the deleted flags table.
• Add a confirmation message for "restore" button
• Change the font family to match the "flag note"'s github style

Motivation and Context

How Has This Been Tested?

Tested locally.

Types of changes

• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to change)

Checklist:

• My code follows the code style of this project.
• My change requires a change to the documentation.
• I have updated the documentation accordingly.
• I have added tests to cover my changes.
• All new and existing tests passed.

[codecov-commenter]

Codecov Report

Merging #393 into master will not change coverage.
The diff coverage is n/a.

@@           Coverage Diff           @@
##           master     #393   +/-   ##
=======================================
  Coverage   83.01%   83.01%           
=======================================
  Files          27       27           
  Lines        1755     1755           
=======================================
  Hits         1457     1457           
  Misses        214      214           
  Partials       84       84           

---

Continue to review full report at Codecov.

Legend - Click here to learn more
Δ = absolute <relative> (impact), ø = not affected, ? = missing data
Powered by Codecov. Last update 11146d8...2140d41. Read the comment docs.