How to fix Wordpress admin bar destroying 100% height

I'm creating a web site that fits to the screen with Wordpress.

When the site owner logs in, the admin bar will appear but it adds the following style:

html{ margin-top: 28px !important; }

This causes a vertical scroll bar to appear. Is there any way to fix this using just CSS?

Someone had a similar issue but he got no answer.

My relevant html structure:

<html>
   <body>
       <div id="page">
       <div class="site-main" id="main"> 
               <div class="content-area" id="primary">

                   <div role="main" class="site-content" id="content">

                   </div><!-- #content .site-content -->

               </div><!-- #primary .content-area -->         
           </div><!-- #main .site-main -->
       </div><!-- #page -->

       <div id="wpadminbar">

       </div>

   </body>
</html>

And relevant CSS:

html, body, #page {
    width: 100%;
    height: 100%;
    min-width: 350px;
    margin: 0;
    padding: 0;
}
#main {
    height: 100%;
}
#primary {
    float: right;
    width: 100%;
    margin-left: -200px;
    height: 100%;
}
#content {
    margin-left: 250px;
    height: 100%;
}

For the admin bar:

#wpadminbar {
  height: 28px;
  left: 0;
  min-width: 600px;
  position: fixed;
  top: 0;
  width: 100%;
  z-index: 99999;
}

I've tried using (negative) margins and paddings, also setting the admin bar's position to absolute instead of fixed but no luck.

Solution

Look into wordpress/wp-includes/class-wp-admin-bar.php at the beginning, and you will find this. Watch closely the comments for the actual answer:

if ( current_theme_supports( 'admin-bar' ) ) {
  /**
   * To remove the default padding styles
   * from WordPress for the Toolbar,
   * use the following code:
   * add_theme_support( 'admin-bar', array( 'callback' => '__return_false' ) );
   */
  $admin_bar_args = get_theme_support( 'admin-bar' );
  $header_callback = $admin_bar_args[0]['callback'];
}

if ( empty($header_callback) )
  $header_callback = '_admin_bar_bump_cb';

add_action('wp_head', $header_callback);

wordpress/wp-includes/admin-bar.php contains the default implementation of _admin_bar_bump_cb:

/**
 * Default admin bar callback.
 *
 * @since 3.1.0
 */
function _admin_bar_bump_cb() { ?>
<style type="text/css" media="screen">
  html { margin-top: 28px !important; }
  * html body { margin-top: 28px !important; }
</style>
<?php
}