Problems changing font-size

Nice plugin!

I’m having trouble changing the font size in the CSS file. I’m wanting to change the header and paragraph text. When I do, it does not seem to register. http://judyasman.com/blog-content-marketing-how-tos/

Can you please let me know if I’m doing it correctly? Here’s what I’m changing:

ul#post-tiles li a h3{
	margin: 0 0 10px;
	text-transform: uppercase;
	font-size: 14px;
	color: #ffffff;
	line-height: 17px;
	letter-spacing: 0;
}
ul#post-tiles li a p {
	margin: 0;
	color: #ffffff;
	font-size: 11px;
	line-height: 15px;
}

It looks like when I changed the font size for the category key, it worked fine.
Thanks for your help!

https://ww.wp.xz.cn/plugins/post-tiles/