##<paper-checkbox>
paper-checkbox is a material design checkbox.
User can tap the checkbox to check or uncheck it. Usually you use checkboxes
to allow user to select multiple options from a set. If you have a single
ON/OFF option, avoid using a single checkbox and use paper-toggle-button
instead.
Example:
<paper-checkbox checked>Checked</paper-checkbox>
<paper-checkbox class="styled">
Checkbox
<span class="subtitle">
With a longer label
</span>
</paper-checkbox>
<paper-checkbox disabled>Disabled</paper-checkbox>