Menu layout broken in Muffin Theme at 1250 to 1330 width

Question

When Muffin Theme's width is from 1250 to 1330 pixels it becomes transparent.

Take a look at these screenshots taken in Muffin demo (http://gdon.unaux.com/muffin/):

1250 px

https://image.prntscr.com/image/cmk6UrBGSO6Uq_qPz417Cg.png

1330 px

https://image.prntscr.com/image/7_giqEoGTvie_vKVorzFvg.png

Answer 1

Thank you for your feedback @Ronlaw.

This issue happened while fixing another issue on the Statistics Tooltips, meaning the text description when you hover the question's statistics.

This fix will be implemented on the next theme update.
Meanwhile if you do want to fix this, you can simply add the following CSS code to your  custom-styles.css  file situated on the CSS folder.

.qa-nav-main {
    z-index: 100;
}