You can adjust the spacing between your thumbnails when they are displayed in your Gallery or on your Portfolio Website.
Portfolio Website
In the website builder, navigate to the album you want to edit and open the photo grid menu by selecting Change Album.
Under View Settings, go to the Spacing between thumbnails dropdown and choose from tiny, small, medium, or large sizes.
Now, you will see that photo thumbnails have different spacing between them.
Gallery
To add spacing between thumbnails in the Gallery, navigate to the album you want to edit and select Customize Album.
In the Appearance section, in Spacing between thumbnails, choose from tiny spacing, small, medium, or large sizes.
Go to View in Gallery to see how the thumbnails look with the applied spacing.
You can add spacing between thumbnails as a default setting for all new albums in Account Settings, under Album and Collection Settings.