[v4] add mobile styles

[katydecorah]

• briefly describe the changes in this PR
• [ ] write tests for all new functionality
• [ ] run npm run docs and commit changes to API.md
• update CHANGELOG.md with changes under master heading before merging

This PR adds styles for a better experience on smaller screens:

• increases font-size of input
• increases width and height of input for a larger hit box
• increases font-size of results

Also fixes the fantom gray background on the clear button #211 (comment)

Refs #89

@yuletide can you take a look at this branch to see if these styles help improve some of the issues you were seeing in #89 (comment) ?

cc @scottsfarley93

[scottsfarley93]

👍 styling looks good to me.

Unable been able to play with it on a real phone to see if it fixes the problems @yuletide notes in #89 (comment) but from the devtools mobile view it looks 🔥

[yuletide]

Looks good, except I'm not seeing the width: 100% working

Not quite sure why.

Edit: Some of this is due to how we have the demo page setup. But when I set mapboxgl-ctrl-top-right to width: 100% I get full width but margin issues on the left side. Trying to recall how I solved this before.

[scottsfarley93]

Looks good to me 👌