Widget’s container?

by

It’s the default behavior of a dynamic sidebar to output li tags around widgets. You can override that though in the sidebar declaration.

You would do that by passing the sidebar registration the following additional arguments:

register_sidebar(
  array(
    'before_widget' => '<div id="%1$s" class="widget %2$s">',
    'after_widget' => "</div>"
  )
);