Hi there,
It's a css issue. You can take a look at
the documentation
to get more information but here is what you roughly have to do:
First, find the class or id of the element you want to customize, for example hikashop_category_name for the product name.
Then go to System>Configuration>Display and edit your front end css file.
Add the things you want in this way (it's a class):
.hikashop_category_name{
font-size:16px;
font-family:"Times New Roman", Times, serif;
color:red;
}
This is an (ugly) example but it should give you an idea of how css works.