White space under menu

Have a look at the generated CSS for the page.

This is what is currently there.

.page-header, .has-transparent-header .page-header {
padding: 400px 0 114px 0;
}

This sets the top padding to 400px and the bottom padding to 114px, hence the excessive white space.

header.page-header {
    padding-top: 1em;
    padding-bottom: 1em;
}

To add or override CSS: use the “Additional CSS” option in the customizer. https://codex.www.ads-software.com/CSS#Custom_CSS_in_WordPress

Learn to use the Chrome Developer Tools or Firefox Developer Tools to help you see and test changes to your CSS.

Thank you so much!