Customizing the styles in HTML exports

Is it possible to customize the styles in HTML exports? The font size in tables is very large, due to the browser's default style. I usually edit resulting HTML files, adding font-size: 9pt in the style for tables, but it would be nice if I could have this set by default.

Here's what the table style ends up looking like after adding font-size to it:

    table {
        border-collapse: collapse;
        border: 2px solid #3887B5;
        margin: 0.3em 0.2em;
        font-size: 9pt;
    }