I believe you want .offset().top
instead of .position().top
.
$(window).on('keydown', function (e) {
if (e.which != 40) return true;
e.preventDefault();
var posicao = $('.homeBaixoRodapeTexto1').offset().top;
$('html, body').stop().animate({
scrollTop: posicao
}, 1500);
});
You have to be real careful with this. You're essentially breaking navigation with the keyboard.
Here's a small demo: http://jsbin.com/xecapoyu/3/edit?js,output