Add top-margin based on height of other element with jQuery
$(document).ready(function(){
    if ($('.post_discussion_header').height(79) + 'px'){
        $('.no_0').css('margin-top','110px');
        }
    });
});

if ($('.post_discussion_header').height() == 79){

if (parseInt($('.post_discussion_header')[0].offsetHeight,10) == 79){

$(document).ready(function(){
    if ($('.post_discussion_header').height() == 79) {
        $('.no_0').css('margin-top','110px');
    }
});

if('[object Object]px') {
    ...
}