The Lithium Pro upgrade offers several distinctive features that set it apart from standard reading applications. The most notable is its comprehensive synchronization capability, which uses Google Drive to maintain consistent reading data across all user devices, ensuring your place and preferences are always up-to-date.

Another significant feature is the advanced theme customization system. Users can create and modify their own display themes, adjusting background colors, text shades, and hyperlink hues to their exact preferences. This level of personalization extends to additional highlight colors, providing more options for note-taking and reference marking.

The combination of these features creates a powerful tool for readers who demand both functionality and personal expression in their reading applications. While current limitations exist regarding book file backups, the existing feature set provides substantial value for users seeking enhanced control over their reading experience.

When it comes to e-books, the size of the library and the authenticity of copyrights are crucial factors for any avid reader. Lithium Pro ensures that users have access to a vast collection of e-books, all verified for copyright authenticity.

The app leverages Google Drive to keep your data backed up and in sync across multiple devices, ensuring you never lose your place in your digital library. Although book files themselves aren't currently backed up or synced, this feature provides peace of mind for your reading progress and settings.

By integrating with Lithium, the free version of the app, Lithium Pro activates advanced features that enhance your reading experience while maintaining legal integrity and respect for authors' rights.

Format compatibility is essential for readers who switch between devices or prefer different file types. Lithium Pro supports a wide range of e-book formats, making it versatile and user-friendly.

After upgrading, users can customize their reading experience by adjusting display settings. This includes changing page background color, text color, and link colors through custom themes, which demonstrates the app's commitment to format adaptability.

With additional features like more highlight colors and future updates planned, Lithium Pro ensures that no matter what device you're on, you'll enjoy a seamless and personalized reading experience.