Dropdown not visible on mobile / scroll bars shown

Looks fine for me, seems the screenshot you post has been taken while you login, it might from the admin css, could you please test it without login and if you can produce the problem then list me clear steps with version of the browser and device and full screenshot will be great

The problem is not from the module it self, its related to where you place the block, the navigation region is collapsible because its contain menu item, so its not the right place to put the block, but anyway I adjust the CSS to make it fits your needs by considering your request as the default place.

You could override any css easily in your theme, don't imagine we will write css which fits every possible position for that block.

Moreover providing clear steps to produce the problem and sending better screenshot would be helpful especially in CSS case, you showing corner which with gear which means other CSS is loaded.

@hass I add Demo link for the project, You can check it.
I will update the picture in the project page, and also the description to have it more clear, and also I think i should write some examples how to adjust the CSS, you right.