The blurb background colour on hover can be changed in this section of CSS:

/*Change the header and column background colour on hover*/

.ds-advent-21 .et_pb_column:hover .et_pb_module_header,
.ds-advent-21 .et_pb_column:hover {
    background: #3A3933;
}

The height of the slider can be changed in this section of CSS:

/*Set the slider height*/ 

.ds-advent-21-slider .et_pb_slide {
    height: 75vh;
}

The colour of the blurb headers are set in the advanced tab of each module and match the colours set for the buttons.