No Margin on Bottom of Cells (Tablet Layout)

Hi there,
Firstly I’d like to say thank you for this awesome page builder – especially as its core functionality is free.
The only shortcoming I find with the builder is the lack of customisation options for Tablet Layout.
As an example:
I have created a 4 cell row with the layout builder and it looks great on desktop and mobile view. However, when using the Tablet Layout the cells have no bottom margin and are stuck together.
This is caused by following bit of code near the footer:

<style type="text/css" media="all"
    id="siteorigin-panels-layouts-footer">/* Layout w5e3d4321bd97c */
    @media (max-width:1024px) and (min-width:781px) { #pg-w5e3d4321bd97c-0.panel-no-style, #pg-w5e3d4321bd97c-0.panel-has-style > .panel-row-style { -ms-flex-wrap:wrap;-webkit-flex-wrap:wrap;flex-wrap:wrap } #pg-w5e3d4321bd97c-0 > .panel-grid-cell , #pg-w5e3d4321bd97c-0 > .panel-row-style > .panel-grid-cell { -ms-flex:0 1 50%;-webkit-flex:0 1 50%;flex:0 1 50%;margin-right:0;margin-bottom:30px } #pg-w5e3d4321bd97c-0 > .panel-grid-cell , #pg-w5e3d4321bd97c-0 > .panel-row-style > .panel-grid-cell:nth-last-child(-n+2) { margin-bottom:0 }

Unfortunately I cannot find any settings to change this margin-bottom value. There is an option for changing it for desktop and for mobile views. But nothing for tablet view.
Could you point me in the direction of where I can alter css settings for tablet view (hopefully without having to mess with the core files themselves)? If there is no such option, is there a plan to add the same customisation features for tablet as there are for mobile?
Many thanks.