Increase Page Source

Good afternoon,

I have a table and inside it I call an iframe in which I call another site. I have a function in javascript to increase and decrease font of the components of the page, but everything inside the iframe does not change.

JS Code:

$('.BTAumentarFonte').click(function () {
        //span
    $('.TBMainTableMP2 span, .TBMainTableMP2 p, .TBMainTableMP2 a, .TBMainTableMP2 div, .form-control, .TBMainTableMP2 iframe').each(function(){
        var tamFonteAux = $(this).css('font-size');
        var tamAux = tamFonteAux.length;

        var tamFonte = parseInt(tamFonteAux.substr(0, tamAux - 2));
        //if((tamFonte > 21) || (tamFonte < 10)){tamFonte = 10;}

        if (tamFonte < 22) {
            $(this).css('font-size', tamFonte + 1 + 'px');
        }
    });        

});

$('.BTDiminuirFonte').click(function () {
    //span
    $('.TBMainTableMP2 span, .TBMainTableMP2 p, .TBMainTableMP2 a,.TBMainTableMP2 div, .form-control, .TBMainTableMP2 iframe').each(function(){
        var tamFonteAux = $(this).css('font-size');
        var tamAux = tamFonteAux.length;        
        var tamFonte = parseInt(tamFonteAux.substr(0, tamAux - 2));     
        //if((tamFonte > 21) || (tamFonte < 10)){tamFonte = 11;}

        if (tamFonte > 10) {
            $(this).css('font-size', tamFonte - 1 + 'px');
        }
    });
});

This TBMainTableMP2 is my table class and inside it I want to get the iframe tag and increase the fonts it has inside. Does anyone know what I need to change to work?

Thank you in advance.