your issue is because all your text is raw in a list item and then your last paragraph is h4.
Using dev tools on chrome i clicked the li element and got the font settings from the css.
font-family:"Helvetica Neue", Helvetica, Arial, sans-serif;
your solution would be to -
a. Apply the above rules to your last paragraph. This is a hack.
b. Wrap your li text in paragraph element : like so…
<li><p>....</p></li> and also ditch the h4 for your last paragraph and wrap that in
<p> tags too. This is probably the correct way with quite long list items like yours.
c. style your li in css to look the same as paragraph text in your last paragraph.
As a side note, the h elements are not intended to size paragraph text. they are headings and subheadings with h1 being the main headline.
Hope that helps