Html css layouts- Web Mobile suppoort - html

Question

I have a page set out similar to this:
My question is about mobile support and how should I go about doing the following:
When the user resizes the window to about the size of a smartphone screen, I want to remove the main content, which is everything below the header area/login, and keep only the header, the login form and the footer. So I have been using css media queries to do this. My problem is that my login form markup resides within the header area.
<div id = "header">
<div id= "logo"><img src =""/> </div>
+-------form markup here------+
|<div id= "login-form">..... </div>|
+ ----------------------------+
</div>
<div id= "main-content">
This is where I want to put the login form
</div>
So my question is, How should I do this?
should I just create another css file and link/apply that when the screen width-height is detected to be smartphone size ?
Should I create the markup block inside main-content, and set its css style display to none UNTIL the screen is resized to smartphone size, where a media query is set to change display attribute ?
What is the best way to accomplish this? I greatly appreciate any help and at least, some little explanation to justify that answer. Also links and other references are very welcome !
Cheers..

Answer 1

Use Media Queries to hide and show content based on device or device width/height.
Here's a good Media Queries Cheat-sheet:
http://stephen.io/mediaqueries/
I wouldn't position the form as 'absolute' and put it outside the header as another poster suggested. This is super sloppy and bad practice. What's the 'absolute' form going to be positioned too? The body? Aghh. You'd need a wrapper - and that's just more code. You can do it all via CSS. Just use Media Queries to change the CSS styles for the header, show/hide elements, and reposition.
OR
JQUERY (Not the best route, but for what you want you're a limited without a redesign). I kept it simple for easy explanation. Note, I haven't tested this:
$(window).resize(function(){
var maxwidth = $(window).width(); // get device window width
var form = $('#login-form'); // form
if(maxwidth <= 320) { // 320 px or whatever you want
form.clone().appendTo('#main-content'); // clone form and append to main content
form.eq(0).hide(); // hide first form, the one in the header
}
else {
form.eq(0).show(); // show initial form
form.eq(1).remove(); // remove cloned form, if set
}
});

Answer 2

I can see two ways you could go about accomplishing your goal:
Take your login-form out of the header div, put it in the main-content div and absolutely position it to make it appear inside the header when on a desktop screen, then use a media query to move it to below the header for viewing on mobile devices.
Use your idea of having two login-forms: one in the header, and one in the main-content area. Use media queries to change the display attribute so that the correct login-form is showing at the right time depending on the screen size. I'm not sure if duplicating the login-form is good practice, so I would try option 1 to start.
Let me know if this works out!