Conflicting Absolute Positions

by Rob Swan

77 Reader Comments

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  1. Though web design is a craft, many of us learn alone, and by trial and error. And along the way we pick up assumptions (approximations that allow us to get the job on hand done). At the time we might realise that our understanding of the topic is a bit fuzzy but we probably tell ourselves something like, “Ok, as soon as I meet this deadline, I’m going to take the time to really get to grips with this!”  Then there are more urgent projects, more deadlines, and at some point we forget that our understanding of a particular area is actually based on shaky foundations and we end up making assumptions that are completely erroneous. It takes some perspective to step back from things and question those assumptions and it is a good reflex to have I think.
    By the way, Eric Meyer’s Cascading Style Sheets The Definitive Guide (Eric Meyer, O’Reilly Press) explains very nicely and thoroughly how positioning works.

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  2. @*Anatoly*
    I wasn’t aware of that problem with expressions, thank you. I suppose I line has to be drawn somewhere…

    @*Jake*
    A fine point! Ta.

    @*Drew*
    Your example is really interesting – good work! Great minds hey? ;) I looked at using borders when I was first developing this, but couldn’t get them to play nicely with the background image I was using…

    @*Roger*
    Yes, a print style sheet is definitely a must for this. On the sites that I developed this for the print template printed the main div (the documentation contents) and hid the side div (the tree navigation for the documentation).

    @*Danny*
    Certainly. To give one example; I needed this layout for an online documentation page. The side div contains a very long tree structure referencing all of the methods and functions of the software, the main div contains the documentation pages itself. Based on the results of our initial usability testing the users wanted to be able to cross reference the table of contents with the documentation pages, this is only really attainable by using two scroll bars. This is a fairly standard convention for documentation (see, for example, the Firefox ‘Help contents’).

    @*Everyone else*
    Thanks for the comments

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  3. “Roger Roelofs”:http://www.alistapart.com/comments/conflictingabsolutepositions?page=3#28 :

    Absolutely positioned elements don’t print well. All content that should overflow onto page 2 and following will be cropped. At very least you will need a print style sheet that uses a different technique to achieve the same layout.
    Well, yeah. I would have taken it as read that anyone clued-up enough to be reading ALA would be using a print stylesheet for anything apart from the most trivial of pages as a matter of course…

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  4. Sorry, it’s lost the end of the quote, let’s try again:

    Absolutely positioned elements don’t print well. All content that should overflow onto page 2 and following will be cropped. At very least you will need a print style sheet that uses a different technique to achieve the same layout.

    Well, yeah. I would have taken it as read that anyone clued-up enough to be reading ALA would be using a print stylesheet for anything apart from the most trivial of pages as a matter of course… but not necessarily to achieve the same layout … instead, to adapt the layout to one suitable for printing.

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  5. Very good article. One small error in the html you give the main panel an id=“right” but the css is calling #main.

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  6. Danny Foo: In-window scrollbars can be appropriate for certain types of web-based applications. Maybe true for certain “web pages”, but I’m mainly thinking about web apps. Imagine working in a word processor in which the entire menu and all navigation controls scrolled off the screen as you paged through your document…

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  7. I agree with you, j theis.  I am building an security management webapp and need to follow traditional app conventions – think outlook or an IDE or iTunes.  I resorted to a bunch of javascript to get around the IE limitations that don’t offer the same flexibility and simplicity.  Very excited to see someone else was smart enough to figure this out and generous enough to share it.  Thank you, Robert!

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  8. While, this works nicely for a very simple layout with no styling inside the left and main containers, it will not work for more complicated layouts. 

    1) You cannot use 100% widths inside the containers.  It will create horizontal scroll bars in IE.

    2) If you work around this problem by setting overflow-y to auto and overflow-x to hidden, then IE will just slap the scroll bar on top of the content if the content length dynamically changes or the browser is resized.

    3) It breaks similarly if there is “float:right” inside the divs. 

    The solution I use is to set the overflows with
    overflow:auto;—for safari
    overflow-y:auto;
    overflow-x:hidden;

    Then add another div inside the container.
    conditionally style this div for IE 6 & 7 with
    padding-right:20px;  (make room for the scroll bar)

    That will prevent the scroll bar from placing itself on top of the content.  With these changes, it should work much better with dynamic content.

    If this is for a web app you might as well just use javascript , because web apps already require javascript.

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  9. I’ve been working on a website for almost a year now that has all sorts of pane-stretching, and so far we’ve been doing it all with all sorts of ugly JS. I can’t even begin to tell you how refreshing it is that there is a much more simple technique. Seriously, this just made my day/week. Much thanks and respect.

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  10. I have a similar goal on my page but different design requirements.  My extra requirement is that the side bar move vertically along with the main box.  This is because I have an ad in the side box, and it needs to come into view as people scroll down (thus menu also needs to be fixed not absolute) and because the menu blends into the main page and having a potential scrollbar there will be hideous.  Does anyone know a tutorial or website that does this? 

    The best technique I could come up with uses javascript to resize the menu bar to be the exact pixel width.  I don’t really mind using javascript, but my annoyance is that it is done after the page load and I think it has to be that way, so my page first draws with a % guesstimate based on a few key resolutions and then redraws with pixel perfect accuracy thanks to javascript.  I couldn’t figure out a way to make the javascript that does this before the first draw because the javascript uses DOM to update the width and margins of a bunch of divs.

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  11. Why is it that even on a site devoted to web design, none of the web developers know very much about the languages and APIs they’re using?

    Perhaps because many of us are too busy making websites to study the specs comprehensively? Web design is one of those fields where you learn something when you need it, so overlooking what may seem like an obvious thing is quite easy. Besides, many people generally thought this wasn’t possible (probably through word and mouth) and felt no need to confirm it for themselves (why would they?).

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  12. Robert, a good referencing example indeed.

    But I’ll only use this for a client on a very low budget or if the client requires a very quick reference guide.

    Else for a ‘help’ feature, I’d rather advice them to implement a ‘smarter’ system to help produce a solution for a problem. :)

    Still I really appreciate this tutorial. A good reference for me to keep for future. Regards.

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  13. Check out this method:
    http://web.hc.lv/kods/css/raksti/2-kolonnu-majaslapas-izkartojums-ar-css/
    Main content goes first in source, which is better for SEO, usability and accessibility.

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  14. this goes a bit pair shaped in safari for me—safari 1.3.2 (v312.6)

    it’s the strangest bug—i’ve never seen it before, maybe it’s just a bug on my system not one everyone is likely to see? no idea:

    clicking on the “finished layout” link gives the page, but the background, outside of the three main panels, remains what was on the preceding page. and changing the size of the window results in all sorts of pixel distortion and noise in the areas outside of the three main panels. quite a strange, changing as you change the size of the window, mess.

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  15. I have a recurring dream where I write an HTML page, apply CSS rules, and the page renders correctly no matter what the browser. Then I get chased down a corridor by a giant blue lowercase e and I wake up screaming.

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  16. Just wanted to post a thank you, this simplified a dynamic resize I had in a project, and also opened my eyes to a sweet new way of fill-up-page block structuring.

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  17. I particularly like the clarity of your thinking – taking things back to first principles. It is an object lesson in keeping things simple.

    Your solution is just what I’ll need to implement some redesigns of old frame-based websites that I’ve been putting off.

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  18. Thanks.  This was an interesting and helpful little article, Rob.  Nice job!

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  19. Firstly, I have to say this is a fantastic solution; it never would have occurred to me to set more than two positions on an element. Very well-written, too, thankyou very much.

    My first point is; No Need for Dynamic Properties
    This is related to Anatoly Litsov’s point above (dynamic expressions can get very expensive since they constantly update). My solution is simply to use a few lines of javascript to do the same thing – get element by ID, do the math with document.body.clientHeight/Width, and have the whole thing wrapped up in a window.onresize event handler, and all of that within the existing conditional comment.

    You mentioned several problems with javascript solutions, inluding problems with cross-browser event handlers; not a problem here. Your method (as you noted)is essentially serving javascript disguised as CSS, using a conditional comment, so why not serve up regular javascript? Critically, this wouldn’t have as much of a performance hit as dynamic expresions; and in my eyes, commits no more ‘crimes’ than the current method.

    Secondly, An attempt to fix the Opera bug

    That bug annoys me a lot, and I would really rather avoid it if possible (aiming for maximum possible backwards compatibility). So, I dreamt up a possible solution with just one HTML change; a container div around the sidebar, with the following CSS (note, my sidebar is on the right, with HTML source order adjusted accordingly)

    #sideContainer {
    position:absolute;
    top:0px;
    right:0px;
    height:100%;
    width:220px;
    }

    #side {
    padding: 0;
    margin: 0;
    position: absolute;
    top: 100px;
    right: 20px;
    bottom: 20px;
    left:0px;
    overflow: auto;
    }

    The idea being that the container div handles the 200+padding width, and the 100% height of the body (html needs 100% height too), and the sidebar is ‘pinned’ with conflicting absolutes within this box. This works in Firefox 2, Safari 3 winbeta, IE6…but in Opera 8, the behaviour is the same as before! Applying a background color to the container shows that it is, as one would expect, stretching all the way to the bottom of the window, including when the window resizes; but the sidebar within it refuses to pin to it’s bottom.

    I’m stumped. I’m posting in the hope someone will spot a flaw, or be inspired to figure out some other way around this tedious bug.

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  20. There are 2 issues that the article does not address that will have people scratching their heads trying to figure out why things are not working. Both are covered in my article “Frames wihtout frames”

      http://www.fu2k.org/alex/css/frames

    1. When Microsoft released XP2, it upgraded IE6 so that javascript expressions within CSS are not executed if, and only if, the zone which a page resides within’s security is set to ‘High’. Even if javascript is enabled. By default that is usually set to ‘medium’, but in many corporate/institutional settings that’s not the case.

    2. The expression that Rob uses will only work if IE6 is in quirks mode (the example document has an xml prolog which does the necessary quirkifying). See the “Standards Mode compatibility for IE 6” section in my article,  for an extended expression that will work either way.

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  21. @John Campell, others—

    I thought I had a way to fix the 100% & float problems inside the absolutely positioned elements in IE—add position: relative; to the .container divs.

    However, that didn’t do it.  But I was unable to find a problem with floats in IE, anyway, just with width: 100%.

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  22. Why stress about Opera 8? “I love Opera”:http://www.alanhogan.com/conversations/i-love-opera-the-browser , but don’t most users (and there are not many) use the latest version (9), in which there is no bug?  And as noted in the article, it only shows on resize. That’s a user-initiated problem that is fixable by reloading, something an Opera user would likely be intelligent enough to try.

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  23. <div id=“right”> in the example shoud be <div id=“MAIN”>

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  24. I didn’t realise that so many people were vague on positioning so its good that your article brings this to attention.

    As a matter of interest you might like to know that the original example can easily be done without using expressions (and in standards mode)and I have converted one of my very (very old) demos to look like the authors.

    http://www.pmob.co.uk/temp/2scroll2.htm

    or an even older similar example.
    http://www.pmob.co.uk/temp/3scrolling2.html

    Instead of using expressions to subtract pixel heights from 100% you simply apply top and bottom padding to the html element and then IE interprets 100% height of the body from inside the padding thus giving you your gaps at the top and bottom of the page.

    Of course it only works in 100% height scenarios and so is of limited use. I often find that these types of layouts (along with forced fixed positioning examples) only work well in certain situations but not for everything as there are quite often scrollbar issues.

    I also notice this quote early in the article which is a little misleading:


    “Technically you can use both a right and a left property and leave the width as auto. But unfortunately IE does not support this”¦”?—css-discuss

    That isn’t quite true and IE does support the properties left and right at the same time and you would soon see this if you tried it out.

    #main {
    position: absolute;
    top: 100px;
    left: 240px;
    right: 120px;
    background:red
    }

    The misconception arises because the background appears to only enclose the content but if there is enough content then it stretches correctly to the positions defined. In fact this can be cured by giving the inner content “haslayout” and then it works as it should.

    Its only top and bottom positions that IE doesn’t understand when used together.

     

     

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  25. #44: the bug you describe does surely exist. I can confirm both the background from the preceding page and pixel distortion on window resize.

    I am really interested in a solution to this problem. I would like to adopt this approach, but my company officially supports Safari 1.3.2 :=(

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  26. Sorry for the huge text in 55, it looked fine in the preview..

    Scrolling does not work in Safari 1.3.2 – while the scroll bar is moving, the content is fixed, which means that you can never see any content below.

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  27. Excellently post and easy to understand.

    This post has saved a lot of time. Thanks for your time to explain everything.

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  28. The fix is to add height:100% to html tag.

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  29. Has anyone tried using this technique to create a 2- or 3-column layout that goes beyond the bottom of the window and where both or all of the columns stretch to the same height as a “height-defining” column?  I believe I’ve figured out how to do this in all browsers (no, I didn’t use faux columns or funky paddings or margins).  I was wondering, Rob, if you’ve seen this before and if not, if you’d be interested in hearing my method.  I read an article that said this would be the “holy grail” of CSS web design.

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  30. I just found Matthew Levine’s article.

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  31. I use this technique or variants very heavily, thanks to the frames without frames article published (and cited) a while back.

    Be forewarned: VERY rarely, and usually inconsistently, Expressions can cause the IE browser to hang in an infinite loop. What appears to happen is the dimension gets calculated which causes the expression to trigger again, ad infinitum. There are some discussions of this, but I don’t have the links.

    For me, it was the width being adjusted. In the end I had to pull it from the CSS,and put it in a javascript embedded in the footer of the page. I didn’t like doing so, because CSS is where it should be, but I had to. So people should be aware of this. While I was at it, I fixed the opera issues in JS too (window.opera is a good way to object sniff for opera)

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  32. Hi, i was looking for the same layout for some time ago, found the same solution with the absolute positioning of each corner, and ran in to the same problems in IE6 og earlier versions.. After a bid of work i actualy manged to find af solution that works alle the way down to IE5 in pure CSS without the need for Javascript. – Will put it online and post a link if anyone should be interessetet :-)

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  33. Hi.. Haven’t had time to write an explanation, but the code should be pretty strait forward :) (There is a small problem with the positioning og the right side scrollbar in IE6 that i haven’t been able to solve yet, but other than that i works as a charm as far as i can se :)

    http://www.einventions.dk/kongknabe/frameset_layout.html

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  34. Rasmus – see my post 54 :)

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  35. Sorrey.. Missed your post :-)

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  36. Does anyone know of a way that I could achieve a similar effect using the “em” size unit?
    I would like my header to be able to fully encapsulate its text, regardless of the text size the user has chosen.

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  37. I noticed that plenty have reported the problem with absolutely positions containers that incorrectly size containing DIVs with 100% widths.

    I found that it no scrollbar appears in IE7/Win, FF2/Win, O9/Win, NN9/Win, S3/Win.

    The problem I’m experiencing is that I cannot set the height of DIVs to 100% in IE7/Win. It works in all the above mentioned browsers.

    Have anyone got a solutions for this problem?

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  38. Thanks for taking the time to write this great, clear article.

    I’ve done this layout using pure CSS, but using individual BORDERS (as an earlier commenter noted) as if they were margins or padding. The neat trick he didn’t mention: you can set BORDER-COLOR to TRANSPARENT so no need to match background colors or designs. 100% fills the remaining calculated width. You might have to keep an eye on your z-index layering when constructing to prevent mouse events from being captured in the wrong DIV.

     

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  39. Whilst your CSS is clean and effective I thought I should point out a few difficulties that it exposes.
    Firefox has a well known and long established print bug exposed by the use of absolute positioning – content is curtailed, usually to a single page.
    Firefox mousewheel navigation (the autoscroll feature) is also broken.
    Neither of these may be considered show stoppers for some but developers might like to be aware of these issues.

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  40. It looks like #main style is supposed to be the style for <div id=“right”>??

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  41. Whilst the solution is neat and taught me things I didn’t know, I do have a worry about those users who can’t use a mouse for some reason.

    As exampled it seems impossible to get the DIVs to scroll down using keystrokes. It seems to me that a sighted user who cannot use a mouse would be unable to access the text at the bottom of both the DIVs.

    In a similar layout with frames tabbing would give focus to each frame in turn, and then the up and down arrow keys would scroll the individual frames.

    Does anyone have any suggestions?

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  42. I really enjoyed the article.

    One issue I’m having in IE7 is getting a nested DIV to respect the calculated height of the parent div. In Firefox, setting the height property to 100% yields the desired result; that is, a div that consumes the entire height of the underlying element. In IE7, the height is ignored, presumably because the element’s height is calculated rather than specified in CSS.

    If someone has a workaround, I’d be grateful for tips.

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  43. Great article rob. Very clear and concise, eays to follow. Good job.

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  44. Thank you very much for this article. It solved me a month of headache.

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  45. Love this technique. Had no idea this was possible. TY!!!

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  46. The layout I’m stuck with has three fixed width columns. For over two years I have tried different ways to get IE6 (may it someday RIP) to extend the background of the right and left columns all the way to the bottom of the center column (where the varying height main content is). I don’t even have (or need or want) scroll bars.

    Maybe there’s an expression-free method to accomplish this somewhere out there, but I haven’t been able to find it. I’m just glad this approach works perfectly for my purpose.

    Thanks for taking the time to track down and explain a classic head-scratcher to this non-expert.

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  47. Thanks, even if we’re seeing IE6 fade away, it is still very much a reality with Asian users.
    I have been looking for a cross-browser option of pinning a div to the viewport’s height, preferably without the use of jquery or equivalent.
    This is brilliant.

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