I would like to know if I use 3 different css files, will the mobile browser of the iPhone / iPad download all 3 sets of css files, or just the one that is relevant by screen size? by using this.
<link media="only screen and (max-width: 320px)" href="iphone-portrait.css" type= "text/css" rel="stylesheet">
<link media="only screen and (min-width: 321px) and (max-width: 480px)" href="iphone-landscape.css" type= "text/css" rel="stylesheet">
<link media="only screen and (min-device-width: 481px)" href="desktop.css" type="text/css" rel="stylesheet">
I've found the answer to use from http://www.w3schools.com/html5/html5_app_cache.asp
even if you have 3 different css files for the mobile, having css stored to the iphone, will minimize bandwidth to only 1 download of each css and this will speed up the website while using less bandwidth.
create a .htaccess file and place this in.
AddType text/cache-manifest manifest
then create another file called what ever u like demo.manifest and place in
CACHE MANIFEST
# v0.0.1
icon.png
desktop.css
iphone-landscape.css
iphone-portrait.css
then on the html page you have to declare it by doing this.
<html manifest="demo.manifest">
once you update the css and files, you will just need to update the demo.manifest and the browser with download the new version of demo.manifest and all of its contents once more.