One of the popular MI Explorer file explorers is available by default on the Xiaomi MIUI device. There are many MIUI device themes available. This theme is only for Mi Explorer. There are white and dark themes available, you can choose which one you want. Just download the theme from the link below. Follow the post to Download OS Theme Material for MI Explorer (Black and White Themes Available).
About MI Explorer:
MI Explorer is one of the popular file explorer available. It's available on the Play Store to be used for other devices than Xiaomi. Most rooted or custom ROM users prefer MI explorer because of its features and speed. Although sometimes advertising may be a problem but it is still a great feature that offers a file explorer application. So, if you have file explorer, you can try the theme there. A black and white layout theme is available. See the screenshot below for further visual reference.
Download Material OS Theme For MI Explorer:
To apply the theme just download the above themes.
Open the MI Explorer, tap on downloaded themes and click on import.