Hey Tereza,
The Education demo uses the Renew stack and Renew has a padding of 5% 0 5.25%; for the Top Footer and 50px 0 for the Bottom. You can override that by inserting the code below in X > Theme Options > CSS and adjust the padding sizes accordingly using this CSS Padding guide: https://www.w3schools.com/css/css_padding.asp.
.x-colophon.top {
padding: 5% 0 5.25%;
}
.x-colophon.bottom {
padding: 50px 0;
}
If that won’t work, it is possible that you already have custom CSS in your site and there’s a syntax error. In this case, I’d recommend that you always check or paste your custom CSS in CSS linting tools or services like http://csslint.net/ before inserting in your site so you detect errors before using.
Hope that helps.