fix: various issues

[huyenltnguyen]

Checklist:

• [x] I have read freeCodeCamp's contribution guidelines.
• [x] My pull request has a descriptive title (not a vague title like Update index.md)

This PR fixes the following issues:

• Search box having nested focus line on focus
• Advanced search button not having correct icon color
• Buttons in the editor having a border (pointed out by Ilenia)
• Disclosure widget text being unreadable on hover (closes #110)

Screenshots

| Issue | Before | After | | --- | --- | --- | | Focus outline | | | | Advanced search button | | | | Editor buttons | | | | Disclosure widget | | |