Custom background colors different windows

[EverThems]

Hi, So i want custom background color different windows. I load the inline the my another pages (objects..), and the defaq background the black (50%). But i want the id="page1" background color is transparent, and id="page2" background red.

So, can possible customize the background? I try it is, but its not working:

I found the .lity css selector is grandted the black background color, but i dont know, how possible customize different div ID(s) the color.