GraphicToronto on "[Plugin: SideOffer] Hide Plugin on Mobile"

you need to place the css into the sideoffer.php file thats located in /wp-content/plugins/sideoffer on your wordpress installation. you'll then scroll down to where it says SideOffer CSS paste the code you have above just before the line "</styles>", see below...

/*** SideOffer CSS ***/
// Enqueue CSS
add_action('wp_head','hd_sideoffer_css',100);
function hd_sideoffer_css() {
?>
<!-- SideOffer [HD] CSS -->
<style type="text/css">
#sideoffer {
background: url('<?php echo get_option('hd_sideoffer_bg'); ?>') top left no-repeat;
width:<?php echo get_option('hd_sideoffer_width'); ?>px;
height:<?php echo get_option('hd_sideoffer_height'); ?>px;
position:fixed;
top:<?php echo get_option('hd_sideoffer_top'); ?>px;
<?php echo "right"; //get_option('hd_sideoffer_side'); ?>: <?php echo get_option('hd_sideoffer_in'); ?>px;
text-transform: none;
z-index:99999;
}
#sideoffer .box { position: absolute; right:0; width: 78%; padding: 15px 10px; color: <?php echo get_option('hd_sideoffer_color_text'); ?>; }
#sideoffer p { margin-bottom: 5px !important; }

<!-- THIS IS WHAT YOU NEED TO ADD -->
@media screen and (max-width: 480px) {
#sideoffer {display: none;}
}