Question

Are the same methods used to write CSS only for iPhone in landscape mode?

Answer 1

You could do this

<meta name="viewport" content="width=device-width, 
    minimum-scale=1.0, maximum-scale=1.0">

That forces the iPhone to render viewport the same as the device width.

Then use this css to target the landscape mode, which is +320px wide

@media screen and (min-width: 321px){
    //styles
}