title: How to change the DropdownToggle background color when click DropdownItem list in Bootstrap 4
body: <p>I am trying to change the background colour of DropdownToggle when clicking DropdownItem. Also, change the top and bottom blue border(not sure)? when click the DropdownToggle</p>
  
  <p><a href="https://i.stack.imgur.com/3NY1Q.jpg" rel="nofollow noreferrer">Picture 1: This is the picture that before I click the item such as "AK","CA","DE"</a></p>
  
  <p>When I click the dropdown item "FL" in this case, the background colour change to black, and there are top and bottom blue border around the "FL"</p>
  
  <p><a href="https://i.stack.imgur.com/dVG6D.jpg" rel="nofollow noreferrer">Picture 2: after select(click) "FL"</a></p>
  
  <p>How to change the DropdownToggle background colour when I click the item, i don't want black like the picture, and also try to remove the blue border.</p>