[Sanjip Shah]

@Dominik You can use the following custom css.

/* Content */
body, 
input, 
textarea,
.slogan-wrap .slogan span { 
	font-family: "Arial";
}

/* Navigation */
#access a,
#access select { 
	font-family: "Open Sans";
}

/* All Headings/Titles */
h1, h2, h3, h4, h5, h6,
#site-title,
#site-description,
.featured-text .featured-title,
.slogan-wrap,
.entry-title, 
.custom-gallery-title {
	font-family: "Chiller";
}

You can use the font of your choice instead. The first part, second and third part is for content, menu and titles respectively. You can also separate the selectors as per your need. Hope this helps.