To change the embedded font, please take a look at the head part of the website and find this tag:
<link href='http://fonts.googleapis.com/css?family=Fira+Sans:300,400,500,700,300italic,400italic,500italic,700italic|Lobster&subset=latin,cyrillic' rel='stylesheet' type='text/css'>
To change the font, first go to Google Fonts, choose a font and replace the code above with the generated code.
Next find _base.less file in css/less directory.
On line 4 replace current font family name('Fira Sans') with your new one.
@font-family: 'Fira Sans', sans-serif;