Hiding Categories on Summary Thumbnail Page and Individual Posts

Do you know how I’d hide the categories on the summary page and how I’d do it on individual posts? I looked for old forum posts and tried to following in custom CSS in Appearance -> Editor and in my custom CSS plugin, but it has not had any effect.

.home .post .post-category {
display: none;}
.single .page-title {
display: none;}

Please let me know if there is something wrong with the code above. I’d prefer a CSS fix over a PHP fix if possible since I completely blew up my site the last time I tried to mess with the PHP, but whatever works I’ll try. Thank you!