Post Carousel

I have set the image size to be square, so now the image size is uniform. However because posts titles are different lengths, I still can’t get uniform sizes for the post carousel. I want them to be aligned and the same size. I tried adding this css under my WordPress > Customize >
.rpc-post-title {
height: 56px;
}
Then I added, .rpc-post-title under Additional in my post carousel.
I also tried adding the full css in Additional in my post carousel.
Neither methods worked. Please let me know if I am implementing it incorrectly or if there is another css code I should be inputting.