If you want to set a default font and font size in your WYSIWYG HTML editor, just execute following commands in your editor:
editor.execCommand("FontSize", false, "2");
editor.execCommand("FontName", false, "Arial");
For 'Font Name' you can use values like: Arial, Tahoma, Verdana, etc.
The important note is that font size values are not in pixels!
Font size:
1 = 8pt
2 = 10pt
3 = 12pt
4 = 14pt
5 = 18pt
6 = 24pt
7 = 36pt
Font size:
1 = 8pt
2 = 10pt
3 = 12pt
4 = 14pt
5 = 18pt
6 = 24pt
7 = 36pt