Improve UI/UX in large screens

[enrique-lozano]

Pull request (PR) checklist

Please check if your pull request fulfills the following requirements:

• I've read and understand the Code Contributions Guide.
• I confirm that I've run the code locally and everything works as expected.

Screen recording of your changes (if applicable):

Video.mp4

What's changed?

Design improvements for all the larger screen devices (Windows devices, tablets...). The improvements are:

• Removed the rounded border in the left side navigation bar on desktop screens
• Applied a custom color in the left side navigation bar (the same color as the cards) and remove the gray border divider
• In the stats page, removed the calendar selector from the bottom and placed in the top-right. In that way, larger devices will have more space to see the charts
• Pages with top tabs (stats page, budgets page and budget details page) now align the tabs to the left in larger screens

Does this PR close any GitHub issues? (do not delete)

No