Just putting my resolution here in case it is helpful to anyone else googling this issue. I just found and tried this by googling / reading… I used the BoldGrid backup before changing anything (since I really don’t know a thing about coding CSS).
In the Customize, I went into the Custom CSS/html text editor. Found this part
/* Inside Pages */
.site-content {
margin-top: 10px;
padding-bottom: 25px;
The 10 and 25 were much bigger numbers before. I just adjusted, saved and refreshed the preview in another tab until I got the look I wanted on both a desktop and phone.