WordPress: Customize the CSS for specific pages or posts
WordPress is a very intelligently built content management system (CMS). So intelligent, in fact, that the developers knew WordPress users might have a need to modify specific pages independent of their other pages or posts. To facilitate this, WordPress provides an intuitive CSS class and ID structure which we can make use of.
<body> HTML section of each page will contain a unique class which will allow you to target the specific page or post. Continue reading below for more detailed information.