Feature : Position of main-header should be fixed to access it while scrolling

[Abhinav1148]

Is your feature request related to a problem? Please describe.

When we scroll down the main-header go up and to search anything or to change color theme we need to scroll up.

Describe the solution you'd like

So, If we make the position of main-header fixed we can access it everytime even when we scroll down.

Describe alternatives you've considered

A clear and concise description of any alternative solutions or features you've considered.

Additional context

Add any other context or screenshots about the feature request here.