[whatwg] RWD Heaven: if browsers reported device capabilities in a request header

[Matthew Wilcox]

> On 2/6/12 1:55 PM, Irakli Nadareishvili wrote:
>> Many thanks to everybody who has responded and for a lively and a
productive discussion!
>>
>> Quick clarification: the proposal is to include *device* capabilities in
the HTTP headers, so when we say "screen width and height" we mean device
screen width and height which is constant
>
> Again, it's not constant in the terms that the page sees, which are CSS
pixels, not device pixels.

Media queries and explicit widths make this statement false, in a practical
way. We adjust for physical pixels quite happily by specifying a width on
the image. This is done routinely in all responsive designs simply by virtu
of the images having a width of 100%. They're then down sampled into
physical pixels even though CSS is using CSS pixels.