Revise scroll position calculation in header component

Updated the formula for calculating `inverseYPos` to use a 20% reduction approach instead of dividing by 4 and inverting. This ensures a smoother and more proportional adjustment during scrolling.

frontend/src/app/header/header.component.ts

@@ -29,7 +29,7 @@ export class HeaderComponent {
     const scrollPosition = window.scrollY;
     if (scrollPosition > 0) {
       this.active = 'active';
-      this.inverseYPos = (scrollPosition / 4) * -1;
+      this.inverseYPos = scrollPosition - (scrollPosition * 0.2);
     } else {
       this.active = '';
     }