Enlarging font & centering shortcode

Hi,

On the following page, I can’t seem to find how to make this category font larger. I thought it was a header but now I am not sure.
http://chopperskisses.com/product-category/hair-ties/

and also on the main page, the instagram shortcode wont center and when I try, it aligns every photo on top of each other.

Any suggestions?

Thank you so much!!

https://wordpress.org/plugins/woocommerce/