Change menu font sizes

Hi there: I really like this theme, but am finding modifying for my needs to be more difficult than it should be. I’ve tried both a child theme and the custom CSS box to get the menu items in the secondary navigation menu to render in a larger font size, and no good. Please let me know if there is somewhere else I should be looking to change this. The box height changes with the line-height mods, but the text stays the same tiny little capital letters.

Here’s my CSS:

div.secondary-navigation {
font-size: 18pt;
line-height: 2em;
}

ul.secondary-nav {
font-size: 18pt;
line-height: 2em;
}

Thank you!