Photobrowser does not show close button

As per above image photobrowser not showing close button in production build.
but bellow image is development build. there close button is showing.

Please help for soultion.

same thing happenes with selected menu.
development build shows selected menu with rectangle background color
while production build only shows text color but no rectangle background color for selected menu

Problem has been solved.
After production build CSS preprocessor plugin gives problem. After changing in webpack.config.js problem has been solved.