A bug exists in version 4.1 of ShowTime where if you choose to always keep your search bar visible, an extra rectangle will show up next to it as shown below.

This has been corrected in version 5.0, but if you are using 4.1, please follow these steps to resolve the problem:

1. Click the Online Store, then Themes link on the left side of your Shopify dashboard and look for the ShowTime theme.

2. Click the the ... button and choose Edit HTML/CSS from the drop-down menu as shown below.

3. Open the Assets folder and locate the file style.css.liquid.  Click it to open it in the built-in editor.

4. Hit Control + F (CMD + F on a Mac) and search for #header .menu_c.  It may appear multiple times, but the one we're looking for looks like this:

#header .menu_c {
margin: 0;
padding: 0;
z-index: 99;
max-height: 500px;
overflow-y: scroll;
}

Replace that with:

#header .menu_c {
margin: 0;
padding: 0;
z-index: 99;
max-height: 500px;
overflow-y: auto;
}

That should resolve the issue.