Finalize UI with Customization Options

[slammingprogramming]

Add themes, custom layouts, and filter options for data views.
Optimize UI for both desktop and mobile screen sizes.

[slammingprogramming]

To clarify: the mobile screen size option is NOT for Android or iOS but rather is for small screen sizes for systems still running Windows, Linux, or macOS so that both larger and smaller screen sizes can be supported.