Toolbox search for mobile

[tracygardner]

• Review UX and adapt as needed
• The toolbox is very narrow due to use of icons. Should it expand on use?
• Tap target for the x to clear the search box is very small

[lawsie]

#654 and #658

• Toolbox search on portrait mobile (up to 480px width) now reverts to a mobile-first approach

• Searching on a tablet (480px to 780px width) slides out the search box for clarity but retains the flyout search results

[lawsie]

#659

Fixed icon display and focus highlight on mobile. Added slight whiter tint to submenu items.