Style needs update on preferences > search

[bsclifton]

Did you search for similar issues before submitting this one?
Yes

Describe the issue you encountered:
Styles in preference screen (about:preferences#search) don't look correct

Expected behavior:
style for the table / headers should look similar to this:

• Platform (Win7, 8, 10? macOS? Linux distro?):
  All
• Brave Version:
  0.12.3
• Steps to reproduce:
  1. Launch Brave and visit about:preferences#search
  2. notice the styles
  3. Press cmd+y or ctrl+y to view history page styles
  4. styles on search page (sortableTable) should be similar to this
• Screenshot if needed:
  
• Any related issues:
  History columns have style issues #4492