Adding some code in style.css but shows nothing

Hi, I have put this code in style.css:

/* Reduces the title font size and displays more than two title lines */
.yarpp-thumbnail {height: 200px !important;}
.yarpp-thumbnail-title {font-size:0.8em !important; max-height: 4em !important}

/* Centers the thumbnail section */
.yarpp-related-widget {text-align:center !important;}

But there is not any effect to My YARPP ??

https://www.ads-software.com/plugins/yet-another-related-posts-plugin/