Sticky Footers for Thesis Theme on WordPress

custom.css

html, .custom {
 height: 100%;
}

.custom .wrapper {
 min-height: 100%;
 height: auto !important;
 height: 100%;
 margin: 0 auto -100px; /* the bottom margin is the negative value of the footer's height */
}

.custom #footer_area, .custom .push {
 height: 100px; /* .push must be the same height as .footer */
}

custom_functions.php

// sticky footer
function div_push() {
?>
<div class="push"></div>
<?php
}

function div_wrapper_start() {
?>
<div class="wrapper">
<?php
}

function div_wrapper_close() {
?>
</div><!--end wrapper-->
<?php
}

add_action('thesis_hook_after_content_area', 'div_push');
add_action('thesis_hook_before_html', 'div_wrapper_start');
add_action('thesis_hook_after_content_area', 'div_wrapper_close');