The fact that 

    <style type="text/css" media="screen">
    	html { margin-top: 32px !important; }
    	* html body { margin-top: 32px !important; }
    	@media screen and ( max-width: 782px ) {
    		html { margin-top: 46px !important; }
    		* html body { margin-top: 46px !important; }
    	}
    </style>

is added for Admin bar by wp-core at the top of the site.

The trick below will remove those CSS out from yout HTML output Just add this code to your `functions.php`

    add_action('get_header', 'my_filter_head');
    
    function my_filter_head() {
       remove_action('wp_head', '_admin_bar_bump_cb');
    } 


**UPDATE**

Answering question-starter request.

**1)** Admin Bar is showing by default if you're logged in. It wrapper has `id="wpadminbar"` in your HTML responce.

It also enqueue `/wp-includes/js/admin-bar.min.js` script and add "Support Script" at the bottom of page.


**2)** Admin Bar can be disabled when you're viewing site for specified users at 
Users -> User_Record -> "Show Toolbar when viewing site" checkbox. 

Additionally it can be disabled in your `functions.php` (using [`show_admin_bar`][1] filter as described here [How do I remove the admin bar (styling) from frontend only?][2])

**3)** In WP source code `_admin_bar_bump_cb()` looks like this. It can be found at [`wp-includes/admin-bar.php`][3] 

    function _admin_bar_bump_cb() { ?>
     <style type="text/css" media="screen">
         html { margin-top: 32px !important; }
         * html body { margin-top: 32px !important; }
         @media screen and ( max-width: 782px ) {
             html { margin-top: 46px !important; }
             * html body { margin-top: 46px !important; }
         }
     </style>
     <?php
    }

This function is used to be added as action to `wp_head` inside [`wp-includes/class-wp-admin-bar.php`][4] in this way:

    if ( empty($header_callback) )
       $header_callback = '_admin_bar_bump_cb';
    
       add_action('wp_head', $header_callback);


By removing `_admin_bar_bump_cb` from action queue you cancel those styles printing


  [1]: https://codex.wordpress.org/Function_Reference/show_admin_bar
  [2]: https://wordpress.stackexchange.com/questions/30309/how-do-i-remove-the-admin-bar-styling-from-frontend-only
  [3]: https://developer.wordpress.org/reference/files/wp-includes/admin-bar.php/
  [4]: https://developer.wordpress.org/reference/files/wp-includes/class-wp-admin-bar.php/