CSS for Text Widget problem

On my website, https://habitswap.com/, I want to change the paragraph spacing of the text in the text widget on the right.

In the text widget, I have the following code:

<h5>
<a href="https://habitswap.com">habit swap</a> is about learning to pay attention to the most detrimental behaviors that rule our lives and swaping them with new habits that are far more useful. Recognize how worthless some of the habits you have formed are and search for motivation to replace them with much more positive, long lasting patterns of behavior.</h5>

I am using a plugin to add CSS. This is the CSS I have added:

h5 { color: #grey; font-size:11.5px; font-family: arial, Helvetica, sans-serif; font-weight: 100;}

Please let me know what I can add to the line above to make the paragraph spacing larger.

Thanks.