How to reduce nav menu height

Hello- twenty twelve theme child here

I’ve increased the font size in my navigational menu to 14px which increased the height of the menu. I’d like to reduce to a height of 30px? How do I do that?

Here is my current style code:

.main-navigation {
    margin-top: 0;
height:30px;
padding: 0 0 20px 0;
float:left;
text-align:center;
width: 100%;
letter-spacing:4px
}

main-navigation li a,
	.main-navigation li {
	margin: 0px 35px 0 35px;
font-size: 14px;
font-family:BentonSansCond Regular, Helvetica, Arial, sans-serif;
	}

Thanks