UX/UI tweaks

[inglenet]

@tripledoublev listing out some remaining UX/UI tweaks to make (based on what we chatted about/what I've adjusted recently) so that we have them in one place:

for now:

• [x] Update font sizes
• [x] Update search bar for desktop and mobile
• [x] Update mode-switcher
• [x] Update mode buttons on welcome page
• [x] Update submission button
• [x] Update filter button

for future iteration:

• [ ] Update search results sidebar (more details in figma comments)
• [ ] Add hover state for search results (changing pin colour to opposite)
• [ ] Add selected state for clicking on a pin/opening a pop up (changing pin colour to opposite)
• [ ] Add selected state for opening the (counter)monument sidebar (changing pin colour to opposite + zoom in?)
• [ ] Add gestural zoom for mobile
• [ ] Add keyboard shortcuts for desktop (e.g. +/- to zoom)
• [ ] Change copy from 'needs further research' to 'no data available' or leave blank

[writerly03]

I made one change here; moved update search bar results to the 'do later' section