Reply To: Site title and description font size

Add this to Additional CSS, changing the font-size to suit.

.site-title{
    font-size: 28px;
}

#site-description{
    font-size: 12px;
}

If you also want to change the font size of the site title in the sticky header when scrolling down the page, this will do it:

#masthead.scrolled .site-title{
    font-size: 24px;
}