gtk/filechooser: Adjust the new folder button styling

src/gtk/sass/_common-3.20.scss

@@ -3476,7 +3476,7 @@ filechooser {

                                
                                
                                
                            
                                
                                    
                                        
                                            3476  
                                            
                                        
                                        
                                            
                                            
                                            
                                            
                                        
                                    
                                
                                
                                
                            
                                
                                    
                                        
                                            3477  
                                                // The new folder button
                                        
                                        
                                            
                                            
                                            
                                            
                                        
                                    
                                
                                
                                
                            
                                
                                    
                                        
                                            3478  
                                                > stack > box > button {
                                        
                                        
                                            
                                            
                                            
                                            
                                        
                                    
                                
                                
                                
                            
                                
                                    
                                        3479 -
                                              @extend %button-flat;
                                        
                                        
                                        
                                    
                                
                                
                                
                            
                                
                                    
                                        3479 +
                                              @extend %button-flat-activatable;
                                        
                                        
                                        
                                    
                                
                                
                                
                            
                                
                                    
                                        
                                            3480  
                                            
                                        
                                        
                                            
                                            
                                            
                                            
                                        
                                    
                                
                                
                                
                            
                                
                                    
                                        
                                            3481  
                                                  border-radius: $circular-radius;
                                        
                                        
                                            
                                            
                                            
                                            
                                        
                                    
                                
                                
                                
                            
                                
                                    
                                        
                                            3482  
                                                }