Replace label with placeholder

Hi
I would like to replace the labels in your plugin with placeholders to save space, resp. making a horizontal login like e.g. used on ww.wp.xz.cn.

Is there any chance to overwrite the plugin? Modifying the core files is not my goal.

Thanks for your feedback and greetings!
Adriano

https://ww.wp.xz.cn/plugins/login-sidebar-widget/