title: How can I set an rgba background-color from Redux Framework color_rgba-type?
body: <p>I'm trying to add an options in my theme settings to set the background-color of my mobile-menu using Redux Framework.
  I used the color_rgba type so I can pick a color with opacity.</p>
  
  <p>I see my background-color set on my menu with class 'mobile-menu', but only a HEX value.</p>
  
  <pre><code>Redux::setSection( $opt_name, array(
      'title'      =&gt; __( 'Mobile menu', 'redux-framework-demo' ),
      'id'         =&gt; 'header-mobile-menu',
      'subsection' =&gt; true,
      'fields'     =&gt; array(
              'id'       =&gt; 'header-mobile-menu-background',
              'type'     =&gt; 'color_rgba',
              'title'    =&gt; __('Mobile menu background Color', 'redux-framework-demo'), 
              'subtitle' =&gt; __('Background color for mobile menu overlay', 'redux-framework-demo'),
              'default'  =&gt; array(
                  'color'     =&gt; '#E2E2E2',
                  'alpha'     =&gt; 1
              ),
              'transparent' =&gt; false,
              'output'   =&gt; array(
                  'background-color' =&gt; '.mobile-menu',
              ),
          ),
  
  ) );
  </code></pre>
  
  <p>How can I make sure I get the rgba color instead of the HEX color?</p>