the base font size of our theme here is about 13.6px… its a bit different because we use em units as the base font size instead of px…  and then its inherited from the wp theme…  and then use 95% of that (1em)…

so in your theme, find the #spMainContainer and set the font size there…  will be the base…

MrPapa, I  didn´t find the exact file or line where to put the font size… can you give me a little help?

thanks

in default.php around line 78

#spMainContainer {
    color: <?php echo($mainBackGroundColor); ?>;
    background: <?php echo($mainBackGround); ?>;
    border: <?php echo($mainBackGroundBorder); ?>;
    font-family: <?php echo($mainFontFamily); ?>;
    font-size: <?php echo($mainFontSize); ?>;
    line-height: <?php echo($mainLineHeight); ?>;
    <?php echo($smallRadius); ?>
    padding: 1px;
}

sent the font size to what you want… or you can edit the overlay you are dong and change $mainFontSize instead…

thanks..!  

you are welcome.