Standard Sizes

Hi Astral Support team,

Thanks for providing such a beautiful theme and great support.

Can you please tell me about standard sizes for the following?
1. In Site Identity – Logo
2. Inner Banner
3. Blog post image
4. Post feature image
5. Background image

I have difficult time trying different size and can’t figure out the best size which look equally across different devices.

The page I need help with: [log in to see the link]