Communicate errors with is-danger on the input and a matching help is-danger message. Success states use is-success the same way. Add has-icons-right on control when you show a status icon.
Server vs client validation
Bulma styles states you apply in markup; it does not run validators. In production, set classes from your framework after server-side validation, or toggle them from accessible client-side logic—never depend on color alone.
Loading buttons
Add is-loading to a button during async submits so users see progress without custom spinners.
Important interview questions and answers
- Q: Where do danger styles go?
A: On the control (input is-danger) and the help text (help is-danger) so both border and message reinforce the error. - Q: Does Bulma replace HTML5 validation?
A: No—it styles outcomes; you still use native constraints and accessible error text.
Self-check
- Which class shows a spinner on a submit button?
- How do you pair an error message with a red border?