Inline image logo in Altitude Pro

A user wrote to me:

Would love to know how to use a Retina logo with the Altitude Pro theme. I found a good tutorial that works well with most Genesis themes, but not Altitude Pro. The logo doesn't shrink, as it should, once the Retina CSS is added. Anyway, take a look and let me know. I'm sure a lot of folks would be interested in this. I hope you're well. Thank you!

We can easily set up a responsive retina-ready logo in Altitude Pro using this method.

Step 1

Edit functions.php.

a) Comment out or delete

//* Add support for custom header
add_theme_support( 'custom-header', array(
	'flex-height'     => true,
	'width'           => 360,
	'height'          => 76,
	'header-selector' => '.site-title a',
	'header-text'     => false,
) );

b) Add