Please help me resize the gallery slidehow reel on mobile view

Hi, 

my site is harshanilucas.com and the issue is with section - section[data-section-id="6504766f14e2400d9c7e31ae"]. I need this slide show reel to go smaller on mobile view. I tried using codes on the forum. but they make the section smaller not the image so the images get cut off. 
Im really new to coding so if you could please help me out 

Add to Website > Website Tools > Custom CSS > then save & reload the site

/* Mobile reel */
@media screen and (max-width:767px) {
section[data-section-id="6504766f14e2400d9c7e31ae"] .gallery-reel {
    height: 20vh !important;
}
}