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 non-empty placeholder attribute is required on each <input> as our CSS-only floating label implementation relies on the :placeholder-shown pseudo-element to detect when the input is empty. The placeholder text itself is not visible; only the <label> is shown to users.
Also note that the <input> must come first so we can utilize a sibling selector (i.e., ~).
When there’s a value already defined, <label>s will automatically adjust to their floated position.
Form validation styles also work as expected.
Textareas
By default, <textarea>s with .form-control will be the same height as <input>s.
To set a custom height on your <textarea>, do not use the rows attribute. Instead, set an explicit height (either inline or via custom CSS).
Selects
Other than .form-control, floating labels are only available on .form-selects. They work in the same way, but unlike <input>s, they’ll always show the <label> in its floated state. Selects with size and multiple are not supported.
Disabled
Add the disabled boolean attribute on an input, a textarea or a select to give it a grayed out appearance, remove pointer events, and prevent focusing.
Readonly plaintext
Floating labels also support .form-control-plaintext, which can be helpful for toggling from an editable <input> to a plaintext value without affecting the page layout.
Input groups
Floating labels also support .input-group.
When using .input-group and .form-floating along with form validation, the -feedback should be placed outside of the .form-floating, but inside of the .input-group. This means that the feedback will need to be shown using javascript.
Layout
When working with the Bootstrap grid system, be sure to place form elements within column classes.