Why are extra pixels added to text height?

Question

css

There is a regular ul - div.container>ul.nav>li.nav-link-container*4>a[#]{some link $}
And there is a style -

html{font-size: 16px;}
* {margin: 0;padding: 0; border: 0;}
a {text-decoration: none; color: #232;}
ul {list-style: none;}

In the browser I measure the text size and it is 19px. Why and how to fix?
Here is an example on codepen. In FF it shows 19px.. codepen.io/anon/pen/zvLBEL?editors=110

Answer 1

line-height: 16px;

Answer 2

line-height ?