I found you can edit width and height here, with a little digging...
In the mappity folder in your plugins folder, open "wpgmappity-posts.php"
at line 58, you can edit your parameters by editing line 59 as i did here (in red), to go full width, I'm sure you can enter the same for height.
}
function wpgmappity_shortcode_container_div($map) {
$content = '<div style="width:100%';
$content .= wpgmappity_shortcode_float($map);
$content .= '<div class="wpgmappity_container" id="wpgmappity-map-'.$map['id'].'"';
$content .= ' style="width:'.$map['map_length'].'px;';
$content .= 'height:'.$map['map_height'].'px;';
$content .= wpgmappity_shortcode_float($map);
$content .= '</div>';
if ($map['promote'] == true) {
$content .= '<p style="text-align: center; font-size: 70%; margin: 0pt;" id="wpgmappity_promote_text">Google Maps for WordPress by WPGmappity</p>';
}
$content .= '</div>';
return $content;