5.1.4 forms.base.input-checkbox Checkboxes
If an <input> element has the type='checkbox' attribute set, the form
field is displayed as a checkbox.
It is recommended that you do not style checkbox and radio inputs as Firefox's implementation does not respect box-sizing, padding, or width.
Example
Markup: base/forms/forms-input-checkbox.twig
<div>
<label><input type="checkbox" class="{{modifier_class}}"> Check me out</label>
</div>
<div>
<label><input type="checkbox" class="{{modifier_class}}" value="" disabled> Option two is disabled</label>
</div>
Source:
base/forms/_forms.scss, line 149