Please try this:
$('#b1').linkbutton({
text: '<span style="font-size:18px">Text</span>'
})
Ah! ok!
thanks!
because of I need it often, i've tried to improve it:
$.extend($.fn.linkbutton.methods, {
setFontSize: function (jq,size) {
return jq.each(function () {
$(this).find('.l-btn-text').css('font-size',size);
})
}
});