9 Jul 2009 12 pm eastern

Firefox test page

Firefox gurus, a page demonstrating the Firefox long content bug has been created for your browser fixing pleasure. Kindly visit the test page using Firefox 3.0 and Firefox 3.5 for Windows (and possibly also for Linux). The following defects should be evident:

  • At least half the comments should be cut off by the browser.
  • The footer should be cut off by the browser.
  • The form enabling you to add comments may also be cut off by the browser (or it may be incomplete, or the labels for such things as your name and email address may appear in the wrong location).

View the same page in Safari 3+, Opera 9+, or IE7/8, and compare. In the other browsers, all comments are displayed, the footer is displayed, and the content form is viewable and displays correctly. How often does Firefox compare unfavorably with some of these browsers? Hardly ever. Which is precisely why you want to fix it. (That, and you’d like your users to be able to view all the content on a page, not just some of the content.)

The test page is identical to this 2 July post, with comments frozen as of 9 July 2009, and with the site’s original CSS, which revealed the long content bug in Firefox.

A subsequent 8 July post documents the steps I and two other developers took in order to isolate this bug in Firefox, and the CSS workarounds (suggested by two of the site’s readers) which have since been put in place to cover up for this defect in Firefox. The thread also explains what we changed in the CSS to enable Firefox users to read long content on the site.

The CSS cover-up enables Firefox users to read all the content on long pages, but at a cost: there is a flash of red background during slow load times. And, obviously, it’s better to fix Firefox than to create somewhat flawed CSS workarounds that slightly diminish the experience for all users of the site.

Thanks for your help! Let me and this site’s readers know how we can assist you. And remember, please use the test page (not this page or any other page of the site) to isolate the bug in Firefox.

Read more

  • HTML 5: Nav Ambiguity Resolved. An e-mail from Chairman Hickson resolves an ambiguity in the nav element of HTML 5. What does that mean in English? Glad you asked! — 13 July 2009
  • Web Standards Secret Sauce: Even though Firefox and Opera offered powerfully compelling visions of what could be accomplished with web standards back when IE6 offered a poor experience, Firefox and Opera, not unlike Linux and Mac OS, were platforms for the converted. Thanks largely to the success of the iPhone, Webkit, in the form of Safari, has been a surprising force for good on the web, raising people’s expectations about what a web browser can and should do, and what a web page should look like. — 12 July 2009
  • In Defense of Web Developers: Pushing back against the “XHTML is bullshit, man!” crowd’s using the cessation of XHTML 2.0 activity to condescend to—or even childishly glory in the “folly” of—web developers who build with XHTML 1.0, a stable W3C recommendation for nearly ten years, and one that will continue to work indefinitely. — 7 July 2009
  • XHTML DOA WTF: The web’s future isn’t what the web’s past cracked it up to be. — 2 July 2009

[tags]firefox, browser, bug, firefox3, firefox3.5, windows, linux, bugs, buggery, debugging, demo, testpage, mozilla[/tags]

Filed under: Browsers, bugs, CSS, Design, firefox, Mozilla, Web Design, Web Standards, work, zeldman.com

79 Responses to “Firefox test page”

  1. Bryant Cutler said on

    Firefox 3.5 on linux (RHEL5, 32-bit) does not cut off the page, footer, or comments form… instead, a small section far down the page in the comments has all its pixels compressed into a narrow band, with the rest blank (the background color). Very strange behavior. Perhaps this is related to the page being so long?

  2. Firefox forces orange background flash – Jeffrey Zeldman Presents The Daily Report said on

    [...] As I am not entirely satisfied with this CSS workaround (despite my gratitude to its authors) and as I do not want Mozilla’s engineering wizards to be unable to fix Firefox because of changes to my CSS, I have posted a Firefox test page using the site’s original (perfectly fine, background-flash-less) CSS, and a page explaining the Firefox test page.—JZ [...]

  3. Jeffrey Zeldman said on

    Firefox 3.5 on linux (RHEL5, 32-bit) does not cut off the page, footer, or comments form

    Are you viewing the test page?

    There should not be a problem with this page in any browser.

    The problem occurs in FF 3.x/Win with long pages filled with content. The test page is a demo of that. This page is merely a link to (and explanation of) the demo page.

  4. Ben Carlson said on

    Looks fine to me in FF 3.5 for Mac… Not seeing anything cut off.

  5. Jeffrey Zeldman said on

    There is no problem in FF 3.x/Mac. Only FF3.x/Win (and possibly Linux).

    The test page, using this site’s original CSS, is a duplicate of a live page that revealed defects in FF 3.x/Win.

  6. Siddharth Agarwal said on

    The test page works for me with Firefox 3.5 on Windows 7 RC x64.

  7. Jeffrey Zeldman said on

    The test page works for me with Firefox 3.5 on Windows 7 RC x64.

    Extremely bizarre.

    The original page was cut in half for all Firefox 3.x/Win users.

    The test page is a duplicate of the original page that was cut in half for all Firefox 3.x/Win users.

    Yet so far no one who visits the test page using Firefox 3.x/Win has a problem with it.

    I’m at a loss to understand this. Let’s see how other Firefox 3.x/Win users fare with the test page.

  8. Martin said on

    I’m using Firefox 3.5 on Windows XP (Mozilla/5.0 (Windows; U; Windows NT 5.1; en-US; rv:1.9.1) Gecko/20090624 Firefox/3.5) and the test page is cut off.

    Interestingly, after you’ve put in your fix I don’t see the orange background flash. I am using the greenish color background though.


  9. Michael Hessling said on

    All the content is there (view source), but it cuts off right around comment #44052 (yours). Here’s a screenshot of the footer, complete with title tooltip and Firebug output.

    Disabling various CSS rules (mostly the background colors) doesn’t make the content appear. FF3.0.11 on Win XP.

  10. Ben Carlson said on

    Ah, sorry Jeff, I skimmed the article and didn’t see that it should be viewed in Windows. Just booted up ye ole Win XP machine with FF 3.5, and sure enough, the content container is cut off on a comment you made, right under “Is it wrong to assume that everyone has read A Preview”. That is very strange indeed.

  11. Thobias B said on

    The test page works fine for me.
    I’m using FF 3.0.11 on Windows 7 RC 32-bit

  12. Stefan said on

    The test page is also cut off with FF 3.5 on Windows XP x64.

  13. Dan Wilkinson said on

    Since the bug has to do with the floated #maincontent div being cut off, why not un-float it and just use:

    div#maincontent {
    margin: 0;
    padding: 0 30px;
    width: 490px;

    You then would have to absolutely position the sidebar:


    div#sidebar {
    margin: 0;
    width: 180px;
    padding: 0 20px 36px 20px;
    font-family: “Helvetica Neue”, Arial, Helvetica, sans-serif;

    I haven’t tested this extensively, but it seems to work…

  14. Michel said on

    Firefox 3.0.11/WinXP Pro SP3 (32 bit). Test page is cut off on my side (as I expected).

    As a few users with FF3+/Win7 (32 & 64 bit) report that they don’t see the bug, maybe it’s not present on all versions of Windows?…

  15. JF said on

    The test page is fine using Firefox 3.5 in Windows 7 RC 1 32-bit.

  16. Charles Roper said on

    Just tried it side-by-side on both Windows 7 and Windows Vista with:

    Mozilla/5.0 (Windows; U; Windows NT 6.0; en-GB; rv:1.9.1) Gecko/20090624 Firefox/3.5

    On Vista it definitely cuts off in the same place each time. On Windows 7, not so much. It sometimes chops off the bottom, or goes completely black, or glitchy, but it’s very intermittent. Mostly (about 85% of the time, as a wildly approximate guess) it renders fine, seemingly.

    The Vista machine has an nVidia graphics card, while the machine running Win7 does not. Is anyone seeing this who does not have nVidia graphics?

  17. Michel said on


    I have an ATI card (pretty basic, btw, as it is on a ThinkPad), WinXP SP3, FF 3.0.11. I definitely see the bug on 100% of the test page loads. Hm…

  18. Adam Backstrom said on

    Fails for me in Firefox 3.0.10 on Windows Vista SP1 (32-bit). I get redraw errors below the point of failure when menus overlap the content (ie. the Firefox contextual menu): http://files.getdropbox.com/u/146967/foxy.jpg

    Firefox redraws the orange background if I drag the window off the screen and drag it back.

    Did not notice this error in Firefox 3 on Linux (Ubuntu 9.04).

  19. William King said on

    I am using Windows Vista and Firefox 3.0. The bug is evident. I had this issue a few times before on the web site. I hope they get this bug fixed soon…

  20. Jonathan Porter said on

    Windows 7/64-bit RC1 Firefox 3.5 Nvidia cards .. works fine

  21. Jeffrey Zeldman said on

    Excellent. The bug is evident on most Windows systems running FF 3.0 and 3.5. Great! That means the engineers at Mozilla will be able to work on the bug.

    Since the bug has to do with the floated #maincontent div being cut off, why not un-float it and just use


    The point of this page isn’t to figure out a CSS workaround for a defect in Firefox. I already have a CSS workaround in place on the main site.

    The point of this page is to help the dedicated and talented engineers at Mozilla isolate and fix a bug in Firefox.

    Once they do that, I can go back to my original CSS (which is better for more people than the workaround). I’m using the workaround only because Firefox is broken with respect to long content. I’m not looking for a different workaround, I’m looking for a Firefox fix.

    But thanks for your creativity!

  22. Joshua Melvin said on

    It’s working fine for me using FF 3.0.11 in Windows 7 as well.

    Mozilla/5.0 (Windows; U; Windows NT 6.1; en-US; rv: Gecko/2009060215 Firefox/3.0.11 (.NET CLR 3.5.30729)

  23. Carl Räfting said on

    When visiting the testpage on a Win Xp / FF 3.5, the bug is indeed present. With Firebug i was able to solve the issue, simply by removing overflow: auto; on #wrapper.

  24. Zachary Forrest y Salazar said on

    Maybe you’ve tried this, but I simply removed the “overflow:auto” line from your div#wrapper css class and everything magically reappeared on the test page.

    I know it’s a CSS fix and not what you’re looking for. ..just FYI. Thanks for indulging me.

  25. Michel said on

    @Carl, @Zachary:


    — Zeldman already changed ‘overflow: auto’ to ‘overflow: visible’ (this is the same as you propose, I guess…) and this, indeed, fixed the problem in FF! :-)

    Now it’s time for the Mozilla engineers to guess, though, why ‘overflow: auto’ doesn’t work for Firefox on most Windows systems (and why it works on Mac/Win7)… :)

  26. dreadnaut said on

    Firefox 3.5 on Windows 7 seems to show the entire page for me as well, although starting from comment #44052 the Grab and Drag extension refuses to drag the page, throwing a javascript exception. In particular the .ownerDocument field of the div becomes null below than point. The extension behaves correctly clicking on the background (the body of the page).

    The same can be achieved using the DOM Inspector, using the “Find a node by clicking on it” button. Clicking on the main content div below comment #44052 will give an exception.

  27. dreadnaut said on

    Looking at it again, comment #44052 is located at position x:113 and y:32701, so it probably crosses the 32767 boundary. Programmers will know what this means.

  28. Michel said on

    What is the the 32767 boundary? Never heard of it… (I’m not a programmer, though, but designer/CSS coder.) And why it would appear on WinXP but not on Win7?…

  29. dreadnaut said on

    Signed 16-bit numbers wrap after 2^15, that is after 32767.

    It works fine for me on Windows 7 too, but the Grab and Drag extension refuses to drag the page after that comment, throwing an exception. The same happens if one uses the DOM Inspector and tries to “Find a node by clicking on it” below comment #44052. Apparently the .ownerDocument property for the div node returns null. Clicking on the background of the page (the body tag) works fine.

  30. dreadnaut said on

    Signed 16-bit value wrap after 2^15-1, that is 32767, and go back to -32768.

    The DOM Inspector gives a javascript exception if you try to find-by-click anything below that comment, complaining that the .ownerDocument property for the div is null.

  31. Andrew Rodgers said on

    Not really helping the issue, however, I thought you should know it does the flashing organ background and cut-off on FF v2.0.0.20 on windows as well.

  32. Amy said on

    Interestingly, I decided to test the page in Camino 1.6.8 on my OSX 10.4 Machine and found the same problem. Comment #44052 gets cut off and the footer is gone.

  33. Michel said on


    Camino is Gecko-based, right? Strange that you’re on MacOS X and you see the bug in Camino. Firefox/WinXP has the problem, but Firefox/Mac — no…

  34. Amy said on


    Yes, Camino is indeed Gecko-based. It makes the behavior even more strange…

  35. chandichonk said on

    Firefox 3.5 on os x. Yes viewing the /foxy/ test page. I don’t see anything either.

    Can’t see what the form issues are because on the test page it says I’m:
    Logged in as Jeffrey Zeldman. Log out »

  36. dreadnaut said on

    @Michel: signed 16-bit integers wrap around after 32767, or 2^15-1.
    I see the entire page on Windows 7, but there are still problems: the DOM Inspector gives a javascript exception if one tries to find-by-click any element after comment #44052, complaining about the .ownerDocument property of the div being null.

  37. Porter Glendinning said on

    I think dreadnaut is onto something there. The page cuts off for me, too, in FF/3.5 WinXP, but interestingly, I notice that when you click and drag down in that last visible comment the selection jumps back up to the top of the page, as if the browser’s wrapped the cursor position.

  38. Tony Ayres said on

    No issues with the test page on FF3 on 64 bit Ubuntu:
    Mozilla/5.0 (X11; U; Linux x86_64; en-US; rv: Gecko/2009060309 Ubuntu/9.04 (jaunty) Firefox/3.0.11

    The bug does manifest in FF 3.5 Windows XP SP2 32 bit:
    Mozilla/5.0 (Windows; U; Windows NT 5.1; en-GB; rv:1.9.1) Gecko/20090624 Firefox/3.5 (.NET CLR 3.5.30729)

  39. Dan Wilkinson said on

    I just confirmed what dreadnaut said: it has to do with the size of the #maincontent div. Once it gets larger than 32767px it gets cut off. If #maincontent is 32766px or less it’s fine, but if it’s 32767px or larger it gets cut off. Tested on FF 3.0.11 on Vista.

  40. Michel said on


    Maybe Jeffrey can somehow get in touch with Mozilla engineers… I think that once we know the reason for the bug, it’s like half-fixed, and it looks like we’re approaching this! :)

  41. Dan Wilkinson said on

    I came up with this simplified test page. If you can see a 1px blue border at the bottom it’s not getting cut off. View source for the CSS.

  42. Dan Wilkinson said on

    Err…this is the page: http://wilkinsonweb.com/test/foxy.html.

  43. dreadnaut said on

    A bug for this problem was filed years ago, but cannot be fixed at the moment.

    Native widgets use 16-bit coordinates, and the fix would require some serious work on Gecko, which might be completed for the next version of Firefox.

    See comments after #132 in the bug report for more information.

  44. Bill Woodland said on

    WinXP, FF 3.5, it cuts off at comment #44050 for me. Oddly enough, when I began selecting text from “John said on 5 July 2009 at 2:14 am: e” and dragged the mouse downwards, the browser popped back up to the top of the page, and all was hilighted as if I had been selecting text in the upwards direction. I scrolled back down, and what was hilighted was everything above where I had started.

  45. Matt Lincoln Russell said on

    FYI, in Windows 7 / Firefox 3.5, I can see all the comments, but all links and form elements do not work after your “Is it wrong to assume” comment. By not working, I mean it’s basically frozen. Hovering over links does not change their color or produce their URL in the status bar.

  46. Bill Woodland said on

    Zooming the text size also changes how much is visible. If you come across another site that displays this problem, at least you might be able to shrink the text a bit to read the entire thing, maybe even get to their comment box to point them to Jeffrey’s css workaround until FF gets fixed.

  47. Tim Buchheim said on

    Interesting. The bug shows up in Camino 1.6.x but the page displays perfectly in the Camino 2.0b3 ( 2009060219)

  48. Phillip Chee said on

    The page works fine in FF 3.5 in Windows 7 RC x64:

    Mozilla/5.0 (Windows; U; Windows NT 6.1; en-US; rv:1.9.1) Gecko/20090624 Firefox/3.5 (.NET CLR 3.5.30729)

    But, it is definitely truncated in FF 3.5 in both Windows XP SP3 32-bit and FF 3.5 in Windows Vista Ultimate 64-bit Edition.

    It seems Windows 7 is the only Windows version immune from it. I can also confirm Matt Lincoln Russell’s observation about the links not working at that particular comment and afterward. I did notice that the links near the bottom of the comments section were not working when I first read the page on July 2, but I just assumed FF was behaving badly. Mind you it was only on that original page and no other pages I was reading.

  49. Niek Kouwenberg said on

    I’m getting the cut off page on Firefox as well. Running on Windows Vista Business, and alongside other versions of Firefox (but I doubt if that makes a difference).

  50. dusoft said on

    no cut off whatsoever here on Firefox 3.0.11 on Linux.

  51. Rick said on

    I actually noticed the problem when I was reading the original post, but didn’t really look into it, though I tried reloading the page 2 or 3 times. Visiting the test page, I that was the exact weirdness that I noticed. I’m running on FF3.5/Vista Home 32 bit. And, I was also hoping that if you could separate comments and trackbacks?

  52. Heine said on

    Works fine in Firefox 3.5 on my mac.

  53. Gonzo said on

    Just got curious about the 32767 limit and fired Firebug on the test page. Firebug reports all dimensions and coordinates without any problem, it seams that the JavaScript engine is using more than 32 bits for numbers, while the rendering engine and DOM Inspector use 32 bit integers (as other people reported that DOM Inspector gives exceptions when trying to inspect elements after the break). I am using Firefox 3.5 with Firebug 1.4b on WindowsXP.

  54. Michael said on

    What I’m seeing is a combination of what some other posters have. Win 7 (RC, 64-bit), Firefox 3.5.

    I’m able to see the whole page, and also see the complete form. However, the links are not hovering correctly. Hovering on links actually bring up the title tag from a completely different website. The links don’t work when clicked.

  55. Richard Fink said on

    With so much brainpower at work, I’m sure this will get fixed.
    You said you had some surgery – nothing too major, I hope. Wishing you a speedy recovery.
    Richard Fink

  56. Adam said on

    The testpage, /foxy/, WORKSFORME with Firefox 3.0.11 on Debian GNU/Linux.

    Is there any reason why you haven’t simply filed a bug in Mozillas system for such, or voted for the already existing bug in their bug-tracking system?

    Just curious about all the fuss.

  57. Jeffrey Zeldman said on


    Is there any reason why you haven’t simply filed a bug in Mozillas system for such, or voted for the already existing bug in their bug-tracking system?

    Three reasons:

    1. I haven’t seen the bug myself, I’m only reporting what readers have told me. It will be better if the bug is filed by someone who has actually experienced it on their system. Please feel free to volunteer!

    2. I’m home, recovering from 5.5 hours of surgery which I underwent on Tuesday. I’m forbidden to do anything strenuous. Blogging is something I can practically do in my sleep, having been at it since 1995. But filling out a Mozilla bug form has never worked for me.

    3. Most importantly, a lead Mozilla engineer will be looking directly at this problem, and the test page will enable that engineer to do his job.

    or voted for the already existing bug in their bug-tracking system?

    I’m not sure it’s the same bug.

    If it is the same bug, “voting” for it doesn’t seem like it’s going to fix anything soon.

    By contrast, creating a test page and asking a friend to ask a friend (who happens to be a lead Mozilla developer) to check it out just might get it fixed.

    The current CSS, with its orange background flash drawback, distresses me. The original CSS created a better experience for all users. I long to restore the original CSS, but can’t do so until Firefox is capable of showing long content.

  58. Paul Decowski said on

    I am on Firefox 3 on Ubuntu 8.04 and I’ve experienced even weirder behaviour. I can’t even describe it so here’s a screen capture:

  59. Jeffrey Zeldman said on

    @Paul Decowski:

    Good heavens! I wouldn’t have believed it if I hadn’t seen it. Thanks for capturing and sharing that.

  60. Paul Decowski said on

    No problem, Jeffrey.

    I have now tested it on my home machine with exactly the same setup (FF3 + Ubuntu 8.04) and can confirm the same behaviour.

  61. Mike McMurray said on

    Foxy test looks to work (ie. pass) in FF3.5 and Chrome under Windows 7 build 7100.

    I have also seen the bug Paul Decowski has in long content in Google Reader under FF 3.0.11 both Win XP and Ubuntu 9.04

  62. Adam said on

    @Jeffrey Zeldman: I think it is great that you’re using your web-rep. to get the bugs that annoy you fixed. And I wish you a speedy recovery. Thanks for the thorough answer.

  63. Micheil said on

    Hmm.. I’m using Firefox 3.0.11 on Ubuntu Linux 8.10, and I don’t see this truncation bug, so it may only affect windows users.

  64. Jeffrey Zeldman said on

    Thanks, @Micheil!

    I’m using Firefox 3.0.11 on Ubuntu Linux 8.10, and I don’t see this truncation bug, so it may only affect windows users.

  65. Michael Kozakewich said on

    People have mentioned in a couple comments that it’s cut off after a certain number of pixels, and I’m sure you’re sizing some things in pixels. If you set the dimensions in ems, will it turn into 32767 em instead of 32767 px?

    Maybe you (by which I mean anyone reading this page) could do tests with various elements exceeding 32767 pixels, and set to the offending overflow value.

    Hey, I know a great fix! 7pt pixel font, with lines of text that stretch across the entire screen! Set the leading to a small number, and there you go: You can fit as much text as you can imagine, without ever reaching the pixel limit!

  66. Tom said on

    Looks great in Ubuntu 9.04/FF3

  67. effika said on

    It’s broken in SeaMonkey 2.0a3 (build ID: 20090223135443) and 1.1.17 on Windows XP sp3, too. Not that anybody USES SeaMonkey (there’s like 20 of us), but maybe this will help point out that it’s endemic to the engine and not just Firefox.

  68. jymmyr said on

    The test page breaks near comment 44050 with Fx 3.5 (Shiretoko) running on Ubuntu 9.04 x86_64. When I scroll down from the top of the page I see something like this. However, scrolling up from below the offending area shows no visible anomalies. In my case the footer looks fine, but even though links there and in the comments can be clicked, the text below the offending area cannot be highlighted with the mouse. I’m very scared.

  69. William King said on

    This isn’t specifically about the bug in question, but I have a problem with Firefox 3.5 that I have discovered. I am hoping someone knows what the deal is. For whatever reason, regardless of what fonts families, font sizes, etc. I choose in the CSS, Firefox 3.5 refuses to display it. It has messed up the typography of so many web sites. Instead it displays Times New Roman consistently. Obviously I could go into the options and change this to my desired font, but that will not help the user when viewing the page. Any ideas?

  70. Travis said on

    Cut off during 44050.

    Firefox 3.5 on Vista 64-bit.

  71. Nick Poulos said on

    For me, the test page displays all comments, including the comment form.

    I’m using Firefox 3.5 on Windows 7 RC x64.

  72. 일모리와 웹표준 said on

    [...] Firefox test page » Jeffrey Zeldman 5 days ago [...]

  73. Norman Wingrove said on

    Bottom of page did not show in Firefox 3.5. All OK in 3.5.1

  74. Michel said on


    WinXP? WinVista? Win7? :-)

    May we assume that 3.5 had the bug but it was already fixed in 3.5.1?

  75. Lyndon said on

    excited to used and convert into html5… i have to used this starting now..

  76. Bug 1650 – Display problem for long entry in Drifting said on

    [...] Google search for "firefox windows long page cutoff" turns up http://www.zeldman.com/2009/07/09/firefox-test-page/ which provides evidence that this is a bug in Firefox for Windows. There may be information [...]

  77. John Lascurettes said on

    Has this been filed over at https://bugzilla.mozilla.org/ ? I couldn’t find one.

  78. John Lascurettes said on
  79. John Lascurettes said on

    So, in the end, if you read through all the comments on the original bug (the one that the above bug links to), they’ve fixed it, but only in Gecko trunk 1.92 and that won’t land until Firefox 3.6.x. So current FF 3.0 and 3.5 users will never see a fix for this.

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