title: Genesis Framework - How to change custom header css code?
body: <p>I am using the genesis framework and I want to support a header image within my child theme. I want to change the position of the image that i uploaded to be the header image.</p>
  
  <p>I added this line of code within my functions.php:</p>
  
  <pre><code>add_theme_support( 'genesis-custom-header', array( 'width' =&gt; 213, 'height' =&gt; 300) );
  </code></pre>
  
  <p>Genesis now generates css code for the .site-header within the front page:</p>
  
  <pre><code>.site-header { background: url(http://localhost:8888/studio/wp-content/uploads/2014/09/my_logo.png) no-repeat !important; }
  </code></pre>
  
  <p>I want to change this code, as i want to apply some other CSS stuff to my <code>&lt;header&gt;</code> like <code>background-position</code>, <code>background-size</code> etc. I saw in the official documentation that I can use <code>'header-callback'</code> within add_theme_support, but how does it work exactly? How do i have to write my callback function that WP automatically changes the code which is generated for <code>.site-header</code> as above?</p>
  
  <p>If i change <code>.site-header</code> within my <code>style.css</code> file it changes nothing. It has to be generated as above, but how?</p>
  
  <p>Thanks! </p>