refactor: revert z index change + add y-spacing

Description

In a recent change we modified the z index of the main card component. This had an impact on the connect wallet modal meaning the user options such as changing network and disconnect button could not be selected as the modal was now behind the main component.

This reverts the z index change, then adds some spacing to the footer to enable tokens in the to list to be selectable on short phones.

Other changes

None

Tested

Tested in responsive browser

Related issues

Fixes https://github.com/mento-protocol/mento-web/issues/137

Checklist before requesting a review

[ x] I have performed a self-review of my own code
[ x] The PR title follows the conventions
[ ] I have run the regression tests

mento-protocol / mento-web

refactor: revert z index change + add y-spacing #138

Description

Other changes

Tested

Related issues

Checklist before requesting a review