In the Mozilla, Firefox, or Netscape browsers, the fonts should be set to allow the Java Web Console fonts to be available. Set the options as specified below for each browser.
Edit menu > Preferences > Appearance > Fonts > Allow documents to use other fonts (checkbox)
Tools menu > Options > Content > Fonts & Colors, Advanced (button) > Allow pages to choose their own fonts, instead of my selections above (checkbox)
Edit menu > Preferences > Appearance > Fonts > Use document-specified fonts, including Dynamic Fonts (radio button)