If you're using a layout that includes your theme's styling, it's possible that you see some space or a 'gap' between your header and where your content starts, or between your content and the footer of your page. This space is actually a part of your theme's layout.
Removing the space between your header and your content
The following steps can be taken to close that spacing:
1. Click the first element on the page (i.e. a Container or Image)
2. Look for the Margins setting in the Settings section of the right sidebar
3. Disable the "linked axis" option
4. Set a negative margin on the top (i.e. -50px)
Removing the space between your content and your footer
Removing the space between your content and your footer are very similar
1. Click the first element on the page (i.e. a Container or Image)
2. Look for the Margins setting in the Settings section of the right sidebar
3. Disable the "linked axis" option
4. Set a negative margin on the bottom (i.e. -50px)