For anyone who is interested I solved this using the following CSS:
//background colour
body {background: white;
transition: background 0.5s ease;}
body:has(#block-yui_3_17_2_1_1647613312964_40288:hover)
{background: #99ccff}
I had to change the block id and background colour individually which took a while, and I'm sure there is probably a simpler way but this worked for me, hope it helps someone!
