title: Rails image_tag width attribute to use a percentage / auto value?
body: <p><code>image_tag('batman.png' size:'100%xauto')</code></p>
  
  <p>The size 100% x Auto is ignored as it does not follow the convention outlined in the Rails API.</p>
  
  <p>Is there a way to do this in rails without the need of a global / specific css class?</p>