Correct form checkbox styling

Try to style the checkboxes from below:
https://static.livechatinc.com/8801096/P42JW0D1HQ/d43c0ecd1f76f592f6d8ab0efc410151/chat-485_(1).PNG
To look like this:
https://static.livechatinc.com/8801096/P42I7ZNI3W/0b4751fae65858c6c279e81075882a36/checkboxes.jpg