Second Logo in header

I am trying to add a tagline logo item that right aligns in the header:

http://powerwashingplus4states.com/

I have used code found in support:

Placed this in the functions.php:

function after_head_image_func(){
	echo "<div class='custom_content'><img src='http://powerwashingplus4states.com/wp-content/uploads/2014/09/slogan.png'></div>";
	
}
add_action('ava_main_header', 'after_head_image_func');

And this is custom CSS:

.custom_content{
position: absolute;
top: 0;
right: 0;
}

What can I add to right align it to the edge of the site content and not the entire monitor? And, How can it scale like the logo does for mobile viewing?