Padding around gridded images

Site URL: https://sprout-tuna-swnf.squarespace.com/sell-from-home/video-meeting-preparation

In the custom editor, where I can select how much padding I want between my gridded images, I can only make the padding go up to 50px. However, I actually want the padding to be much bigger than this so the images are much smaller compared to their titles. How can I add more padding around my grid images to help significantly reduce the size of my images?

Add to Home > Design > Custom CSS

div#block-86f7f26916e752a3f194 img {
    width: 50% !important;
    height: auto !important;
}
div#block-86f7f26916e752a3f194 a {
    padding-bottom: 50%;
    margin: 0 auto !important;
    text-align: center;
}

Thanks, that works really well. But how come when I try and do the same thing on another page it doesn't work?

For example on this page is displays like this - https://www.ridgemountpr.co.uk/sell-from-home/online-event-promotion

The code I used was the same as the one as you wrote, but with a different block id. This was the code:

div#block-e4fe438a51cb66847a03 img {
    width: 50% !important;
    height: auto !important;
}
div#block-e4fe438a51cb66847a03 a {
    padding-bottom: 50%;
    margin: 0 auto !important;
   text-align: center;
}

div#block-e4fe438a51cb66847a03 img {
    width: 50% !important;
    height: auto !important;
	top: 0 !important;
}
div#block-e4fe438a51cb66847a03 a {
    padding-bottom: 50%;
    margin: 0 auto !important;
   text-align: center;
	overflow: visible !important;
}