In your stylesheet.css file for your template find the following block of code:

Code:
h1 {
	font-size: 1.5em;
	}

h2 {
	font-size: 1.4em;
	}

h3 {
	font-size: 1.3em;
	}

h4, h5, h6, LABEL, LEGEND, ADDRESS, .larger{
	font-size: 1.1em;
	}

.biggerText {
	font-size: 1.2em;
	}

h1, h2, h3, h4, h5, h6 {
    margin: 0.3em 3px;
}
The margins that are set for h1, h2, h3, h4, h5, h6 do not work too well for h1 and h2.

You can change all of this but a quick fix might be to add a line-height:1em; to the h1 and h2 rules:
Code:
h1 {
	font-size: 1.5em;
        line-height:1em;
	}

h2 {
	font-size: 1.4em;
        line-height:1em;
	}