Workaround sticky buttons in webviews

[tlvince]

According to twbs/bootstrap#13049 (via twbs/bootstrap#12832) :hover styles aren't removed correctly in some mobile browsers.

In Nutsurv, we workaround this by resetting :hover (and :focus) and applying its style on :active:

  /* Workaround "sticky hover" bug */                                                                                                                           
  .btn-default:hover, .btn-default:focus  {                                                                                                                               
    background-color: white;                                                                                                                                              
  }                                                                                                                                                                       
  .btn-default:active {                                                                                                                                                   
    background-color: #e0e0e0;                                                                                                                                            
  } 

Perhaps this is another candidate for a mobile-specific theme?