Unable to close keyboard shortcuts modal/pop-up from Alpha editor in firefox

We are unable to close keyboard shortcut pop-up, tried clicking outside of modal box and pressing Esc button.

Steps to Reproduce:

• Login to zanata

• Click on dashboard and select any project

• Select version and document

• Open Alpha editor

• Click on keyboard icon from top right corner to view keyboard shortcuts

• Observe the close icon not showing on firefox

• Try to close it using Esc key or clicking outside of window

• Observe the behavior

Actual Result:

• Unable to close keyboard shortcuts modal box

Expected Result:

• We should be able to close modal box using Esc key and by clicking outside on modal box.

Note:

• Attached screen captured for more info