feat: added dark and light mode

src/app/app.ts

@@ -1,4 +1,4 @@
-import { Component } from '@angular/core';
+import { Component, OnInit } from '@angular/core';
 import { RouterOutlet } from '@angular/router';
 
 @Component({
@@ -7,5 +7,15 @@ import { RouterOutlet } from '@angular/router';
   templateUrl: './app.html',
   styleUrl: './app.css'
 })
-export class App {
+export class App implements OnInit {
+  ngOnInit(): void {
+    this.initTheme();
+  }
+
+  private initTheme(): void {
+    const savedTheme = localStorage.getItem('theme');
+    if (savedTheme === 'dark') {
+      document.documentElement.setAttribute('data-theme', 'dark');
+    }
+  }
 }