refactor: Apply media queries to the login form of partner page

Description

This PR has the purpose to adjust the login form when the user log in of the partner page from mobile devices. To ensure the legibility of data on small screens, I expanded the available space on the input and I lowered the login button on other line.

Motivation and Context

The intention after applying media queries is to improve the appearance of login form. Currently no responsive styles are applied to the form and when the screen size decreases the input for the address gets smaller making their viewing difficult.

How Has This Been Tested?

After making the changes I ran yarn dev and confirmed that everything appeared as expected

yearn / yPartners