make modal full screen for mobile viewport

[circlecube]

Proposed changes

This makes the mobile styles 100vh and 100vw so that the new ctb products can display properly. Also, some minor tweaks to the close button for layout and clickability on mobile.

See CAP-8658

Type of Change

• Bugfix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to not work as expected)
• Documentation Update (if none of the other choices apply)

Checklist

• I have read the CONTRIBUTING doc
• Linting and tests pass locally with my changes
• I have added tests that prove my fix is effective or that my feature works
• I have added necessary documentation (if appropriate)

Further comments

[circlecube]

Here's a before and after screenshot of these changes:
Before

After

(the desktop view doesn't change - though I did increase height from 550 to 560 after loading a handful of ctb views, this seemed to make most of them a little better and didn't break any)