Under a Hero block, on the bottom of my home page, there is a white blank space.
Even if I delete all CSS or if I build a new Hero, there is always this white blank space.
This removes the themes padding and spacing – which is one of the reasons for the space below.
Then make sure all your content is added inside a GB Container Block to keep content contained whilst allowing for full width backgrounds.
For that last block i would build it using the FB Container, Headline and Buttons blocks. This will remove the bottom margin from the last block which is the another element creating the gap.