title: Date-picker styles not working after production build in Angular 4
body: <p>recently I created a build of my Angular5 app in which I used ngx-bootstrap to show datepicker and modals. It was working very well before production, but after production, build seems like it lost its styling. </p>
  
  <p>please check attached image...</p>
  
  <p><a href="https://i.stack.imgur.com/OZ4vz.png" rel="noreferrer"><img src="https://i.stack.imgur.com/OZ4vz.png" alt="enter image description here"></a></p>
  
  <p>I followed all the implementation steps again, but nothing worked. </p>
  
  <p>Please help to resolve this issue. Thank you so much. </p>