Override Default Font in #fp-nav ul li .fp-tooltip

### Description
Inside the fullpage.css at line 192 under #fp-nav ul li .fp-tooltip selector
a font-family is defined: font-family: arial, helvetica, sans-serif;

When my website uses another font for example defined at body, I have to override fullpage.css by creating a targeted selector again #fp-nav ul li .fp-tooltip

It would be better for fullpage.js not to use a self defined font, and be able to use the default defined at the website we are using the library on.