To reduce the top margin of the footer you can acually use negative values.
Below are mine values for this patch section.
Code:
# Example for Glo/Aura:
replace_string = D54355, `min-height: 70px;`, `min-height: 20px;`
replace_string = D54368, `max-height: 70px;`, `max-height: 20px;`
replace_string = D54385, `footerMargin: 40;`, `footerMargin: 00;`
replace_string = D5439F, `font-size: 16px;`, `font-size: 16px;`
replace_string = D543B1, `padding-bottom: 0px;`, `padding-bottom: 0px;`
replace_string = D543C7, `margin-top: 0px;`, `margin-top:-5px;`