Layout
              
              Flex row or
              grid component
              allow for a lot of flexibility when building form layouts. Use
              dB and other micro-layout helpers to stack form
              elements.
            
Custom field combinations
Validation states
              To notify the user of validation errors, add
              .is-invalid class to each form control that has not
              passed validation and show an error message below. If a form is in
              an error state, you can also show large
              notification block.
            
              In rare cases you may want to visually highlight sucessfull/valid
              input by adding .is-valid class to the form control.
              Likewise, you can communicate a warning by adding
              .has-warning class.