Close button overlaps other field components

Problem/Motivation

- The multiple field remove button overlaps other components

Steps to reproduce

With the module installed, add a multiple text field to a node, and visit the edit page.

Proposed resolution

Modify the CSS 'top' attribute of the has-multiple-fields-remove-button class from 50% to 33%.

Remaining tasks

None

User interface changes

Button no longer overlaps other components.

API changes

None

Data model changes

None