Floating labels
Create beautifully simple form labels that float over your input fields.
Example
Wrap a pair of <input class="form-control"> and <label> elements in .form-floating to enable floating labels with Bootstrap’s textual form fields. A placeholder is required on each <input> as our method of CSS-only floating labels uses the :placeholder-shown pseudo-element. Also note that the <input> must come first so we can utilize a sibling selector (e.g.,~).
HTML
When there’s a value already defined, <label>s will automatically adjust to their floated position.
HTML
Form validation styles also work as expected.
HTML
Textareas
By default, <textarea>s with .form-control will be the same height as <input>s.