Set orange border on an element in Bootstrap to indicate danger

To set orange border to an element, use the border-warning class ?

  Danger (Orange border)

Set the style for the element ?

Let us see an example to implement the border-warning class in Bootstrap ?

Example

  
    
    
    
    
    
    
    
  

  

    
The following are two Rectangles:
    
Danger (Orange border)