We recommend using client-side validation, but in case you require server-side validation, you can indicate invalid and valid form fields with .is-invalid and .is-valid. free Free Web Design Code & Scripts - CodeHim is one of the BEST developer websites that provide web designers and developers with a simple way to preview and download a variety of free code & scripts. Try changing the Awesome Checkbox class to something else. Find centralized, trusted content and collaborate around the technologies you use most. same line: Radio buttons are used if you want to limit the user to just one selection We use the sibling selector (~) for all our states, like :checked or :disabled. You can easily make select2 select multiple checkboxes in bootstrap 4. Hire our experts to build a dedicated project. Be sure to explore our custom forms to further style via opacity and instead style the