Enhancement: Add Dark Mode Support Across App

[Pratham23003]

Implemented Global Dark Mode with Persistent Theme Toggle

Changes:

• Added .theme-dark support with CSS overrides for:
  • Navigation bar
  • Sections
  • Tables
  • Forms
  • Footer
• Inserted a theme toggle button in navbars on all pages.
• Persisted user preference via localStorage and applied on load.

Files Updated:

• Personal-Finance-Tracker/style.css
• Personal-Finance-Tracker/index.html
• Personal-Finance-Tracker/login.html
• Personal-Finance-Tracker/sign-up.html
• Personal-Finance-Tracker/support.html
• Personal-Finance-Tracker/login.css
• Personal-Finance-Tracker/sign-up.css
• Personal-Finance-Tracker/support.css
• Personal-Finance-Tracker/script.js

Acceptance Criteria:

• Theme toggle button switches between light/dark instantly.
• Choice persists across reloads and pages.
• Footer correctly changes color scheme in dark mode.

Labels: enhancement, hacktoberfest

[neeraj542]

Assigning you @Pratham23003

[neeraj542]

Share updates while you working on the respective issue

[Pratham23003]

Dark mode implementation is complete

-> Added .theme-dark class with CSS overrides (nav, sections, tables, forms, footer, etc.).
-> Integrated theme toggle button in navbars across all pages.
-> Preference persists via localStorage across reloads and navigation.
-> Verified footer color changes and toggle behavior on all pages — all working as expected.

I've opened a PR for this.
Kindly mark it with the hacktoberfest label.

[Athting]

@Pratham23003 plz assign this to me