title: anchor tag custom link button background color change conditionally using css class
body: <p>I am looking for help, I and written some code for css custom button. and using html anchor tag i am invoking css class (:after , :before).but now I JUST want to change background color of this button using another subclass (:disable)
  with condition (if string1 == string2 else default). I think ng-disable does not work along with anchor.</p>
  
  <p>html :</p>
  
  <p><code>&lt;a class=" crumbs" href="url"&gt;Start&lt;/a&gt;</code></p>
  
  <p>looking something like :
  <code>&lt;a class="crumbs "  a-disabled="{$strng == $strng2 }" href="url"&gt;Start&lt;/a&gt;</code></p>
  
  <p>and upon success of a-disabled condition it should add a.disabled css class to change background color.</p>