Looks like there are two distinct questions here:

1) How to make web-embedded CDF content zoom (change magnification) with the rest of the surrounding web page

This is a feature now supported with the release of Mathematica 10, and coming soon with the new CDF Player. You can see this in action (using the Mathematica 10 plugin) at this Tumblr page:

http://arksphere.tumblr.com/

Use your standard web browser view menu zoom settings to see the top example change size with the rest of the page, whereas the older example below it will remain a static size. A CDF must be saved with version 10 to to enable this behavior, and we're in the process of making these updates to all CDFs in our product sites.

2) How to match a CDF based on Manipulate to the size specified your HTML

Interactive diagrams created with Mathematica's Manipulate function are scalable (to the degree allowed by white space within the Manipulate box) and will adjust their size to the dimensions set by the embed code. For fixed dimensions, configure your content with ImageSize or ContentSize set to an explicit value or size specification. ImageSize->Medium will preserve Mathematica's default dimensions.

You'll find this and other details at the "Formatting Your Content for Embedding" section of the CDF website's deployment page:

http://www.wolfram.com/cdf/resources/deployment-details.html

</br>Hope this information helps, and I will make a point to check in later to see if there are more questions/concerns.

This is a good question and I am surprised no-one has come up with an answer so far. I would also like to increase the size of the output cell on my Manipulate exercises.

@Gary, here's my CDF example in its original background:

http://members.wolfram.com/andre/cdf/webscaling

I will take a look at your particular example a bit later today to see if I can be of further assistance, thanks.

Works fine with background color applied to the notebook and exported to CDF with version 10, as shown here:

http://members.wolfram.com/andre/cdf/webscaling/LogFunction.v10.html

I also included a version with the web embed size set smaller than exported size, so you can see the scaling effect from not setting explicit ImageSize for the content (plots). It's the same behavior in a notebook -- if you change the notebook window size you will see the Manipulate shrink rather than be cropped. I'm not a big fan of this behavior on the web, since most developers want the size they see in the exported result and may not find this automatic shrinkage useful.

Anyway, hope this helps!

@Gary, without access to your source notebook, I can only guess that the export process is calculating the embed size based on some additional content that is not displayed. You can surely eliminate the white panel by reducing the object size (note the position of the CDF icon in the lower right corner is based on the object size settings).

I do however recommend you copy and paste the embed code provided by the export wizard, rather than just using the "embed" tag.

@Gary, was hoping to look at the notebook you used to generate the CDF. But I can try stripping this CDF back to its normal notebook state and export it myself to see how it sizes. I'm using Mac btw, and will try Windows as well in case there's something going on there.

As for displaying the CDF in web pages using our JS embed code, your example (from your server) works for me viewing in Safari on Mac and IE on Windows, but not in FireFox or Chrome on either platform. It's possible there is some sort of security aspect to this that needs user interaction, or you need MIME types to be set up (see the CDF again for details on that).

@Andre, I don't understand why you are not seeing the source notebook. It was attached to two of the previous messages. But here it is.

P. S. This code has been edited so it can now be cut and pasted into a notebook, where it should produce a plot.

Gary

Clear["Global`*"]

Manipulate[

GraphicsRow[

{Graphics[{zLine[lnVs[lnPts[mTheta]]],ray[maxr],labelZ},Axes->True,Background->White,PlotRange->{{-2pltRatio ,2pltRatio},{-3pltRatio,3pltRatio}}],

If[mTheta>Pi,
Graphics[{logCrv2[(#-Pi I)&/@logPts[mTheta-Pi ]],logRayCrv[maxr],labelW1,labelW2,piUp,piDwn},Axes->True,Background->White,PlotRange->{{-2pltRatio -5,2pltRatio},{-3pltRatio,3pltRatio}}],

Graphics[{logCrv1[logPts[mTheta]],logRayCrv[maxr],labelW1,labelW2,piUp,piDwn},Axes->True,Background->White,PlotRange->{{-2pltRatio -5,2pltRatio},{-3pltRatio,3pltRatio}}]]},

Background->White,Frame->All,Spacings->0,ImageSize->Medium],

{{mTheta,0,Style["Theta",Bold,16]},0,2Pi},{{maxr,2,Style["r",Bold,16]},0,r},
FrameLabel->Style["The Logarithm Function",16,Bold],

Initialization :> (

logf[z_]:=Log[Abs[z]]+I Arg[z];

v[z_]:={Re[z],Im[z]};

z[theta_,r_]:=r Exp[I theta];

r = 2;

pltRatio = 1.5;

zPts[theta_,r_]:=Table[r Exp[I x],{x,0,theta,.05}];

lnPts[theta_]:= zPts[theta,r];

lnVs[pts_] := v[#]&/@pts;

zLine[vectors_] :={Red,Line[vectors]};

rayPts[maxr_]:=  Table[z[Pi/4,r],{r,maxr,.001,-.05}];

ray[r_] := {Blue, Line[v[#]&/@rayPts[r]]};

logPts[theta_]:=logf[#]&/@zPts[theta,r];

logCrv1[pts_] := {Red,Line[v[#]&/@pts]};

logCrv2[pts_]:={Red,Line[v[#]&/@pts]};

logRayPts[maxr_] := logf[#]&/@rayPts[maxr];

logRayCrv[maxr_] :=  {Blue,Line[v[#]&/@logRayPts[maxr]]};

labelZ = Inset[Style["z",Bold,12],{-2,-3}];

labelW1 =  Inset[Style["w=Log(z)",Bold,12],{-5,-3}];

labelW2 =  Inset[Style["Log(z) = ln|z| + i Arg(z)",Bold,8],{-5,-4}];

piUp = Inset[Style["Pi",Bold,12],{.5,Pi}];

piDwn =Inset[Style["-Pi",Bold,12],{.5,-Pi}];
)

]

@Sam and @Andre, I'm sorry the code didn't work. I see now that I mistakenly attached a .cdf file rather than a notebook, but I did previously attach a notebook in my second message on this thread. I just now opened it from this page and it produced a plot. Nevertheless, a copy is attached with this message. Thank you for the link to the tutorial. When I clicked on the link with the intention of editing the code in the message above, it appeared to respond, but then it returned me to this page, so I was unable to read it.

Attachments:

@Andre, I have been unable to reply for some 5 hours now because the reply button is not functioning. I'm not having trouble with any other sites, so I assume that the server is very busy or down for some reason. I pushed the Publish button and got an editing screen.

You were quite right that I had the notebook magnification set at 150 and that was the problem. I changed it to 100 and the cdf files are all working well now except for an occasional thin white line at the bottom, but I can live with that. Many thanks for sticking with this to the solution. I will just put this together now so that the next person with this question can find it quickly:

My CDF manipulate programs were not displaying properly on the web. White panels were showing between the CDF frame and the web page background.

One should set the size somewhere in the script by including ImageSize --> N (a number) for a fixed size image or ImageSize --> Medium for an image that will resize as the web page is resized. Other possibilities are illustrated in the documentation for ImageSize. Places where one might set the image size include the options of Graphics[], Plot[], or Manipulate[]. I found that setting the size in Manipulate worked, but ImageSize printed Red, suggesting that it doesn't belong in the Manipulate options.

If one wants a colored background for the CDF that matches the background of the web page, that background has to be set in Format --> Background Color. Select the output cell first.

Before exporting, magnification for the web page should be set at 100 percent using Window --> Magnification. If this is not set, the actual size will not match that specified by the CDF Export wizard. I commonly use 150 or even 200 percent for editing, so I have to watch this.

In the source code for the web page where the CDF will be displayed, the bounding box should reflect the height and width given by the Export --> Web Embeddable wizard.