Develop Reference

Header with position:sticky is flickering in chrome when shrinking

I have a navigation element, below some other content, that I should be fixed, as soon as the scroll height is reached. This is achieved with position:sticky and works fine in all browsers. But I also want to shrink that element as soon as it is fixed.
https://codepen.io/arichter83/pen/xMLyOJ
If scrolled slowly at Chrome (71.0.3578.98 64-bit Mac) this header flickers, because if the element is shrinking, the window.scrollY of the page is reduced, which makes the element become larger again... back and forth. (use "start" to see the behavior)
Any workaround for this?
Wrapping in fixed height: this would stop the content below to move upwards, which I want.

Adding a position property to your header.minified ID seems to have stopped the flickering.
#header.minified {
font-size: 24px;
line-height: 48px;
height: 48px;
background: #efc47D;
text-align: left;
padding-left: 20px;
position: fixed;
}

sticky element behaves differently on the poressence of a scroll bar

I am trying to imitate SO page behaviour of having a menu on the left and a bar on the top, both being sticky. The design is a sinle page dynamic application so when I say "switch pages" I am actually changing the html of a single page.
I create a menu as a list and a bar set them to be sticky as follows:
#topNav {
margin: 0px;
width: 100%;
height: 40px;;
overflow: hidden;
list-style-type: none;
color: white;
background-color: rgb(22, 16, 99);
position: sticky;
position: -webkit-sticky;
top: 0; /* required */
z-index: 1;
}
.menu {
margin: 0;
padding: 0;
padding-top: 20px;
position: sticky;
position: -webkit-sticky;
top: 40px; /* required */
border-right: 2px solid black;
}
However what is happening right now is, if there is a scroll bar, the menu is marginally (3 pixels maybe) more to the left than when there is no scroll bar. This creates a really ugly effect since switching between pages with little text to large pages moves everything just enough for it to be human noticeable. How can I prevent the scroll bar from re-formatting the text?

you can set overflow-y:scroll to that container. This makes the scroll always show irrespective of the content. So your content doesn't move around when switching pages.
Update: If you don't want the scroll to always show, you have to detect if the container has a scrollbar through javascript and append a class to your menu that would shift it to it's original position.
Here is a sample fiddle: http://jsfiddle.net/85a0sc4r/

Webpage displays incorrectly on different resolutions due to incorrect css

I'm having some issues with a webpage of mine, mainly on mobile devices but it also affects desktop devices too, I would be willing to award a bounty (as and when stackoverflow allows me) to whomever can help with these problems
HTML: http://pastebin.com/raw.php?i=bbFsMcwT
CSS: http://pastebin.com/raw.php?i=SGMwt3cs
JSFiddle: http://jsfiddle.net/D8SJD/
Issue 1 - Left/Right Scroll Image Buttons
Currently my left and right scroll image buttons are done in html using onmouseover and onmouseout I want to be able to convert them into css based "buttons"
Issue 2 - Dynamic Resolution(s)
The header and footers aren't dynamic with different resolutions for example, I created the page designed on a 1680x1050 monitor which looks like: Desktop 1680x1050 however making the window smaller it looks like: Desktop Small Window
On a Nexus 4 mobile phone on default zoom it looks like: Mobile Original Zoom
On a Nexus 4 mobile phone zoomed out to as far as it can go it looks like: Mobile Max Distance
On a Nexus 4 zoomed out and scrolled to the bottom (so that the browsers URL bar disappears) it looks like: Zoomed out without URL bar (the footer of the actual webpage vanishes)
On a Nexus 4 zoomed out and scrolled just off from the bottom (so that the browsers URL bar is visible) it looks like: Zoomed out with URL bar (the footer returns)
.
The placeholder image and arrows are supposed to be in the center of the footer and headers and should shrink in accordance to the screen resolution.
Mobile device default zoom (if possible) needs to be decreased so they can see more and on getting smaller (if possible) if it gets close to Mobile Original Zoom then the Up to Top, Down to Key, placeholder logos should vanish...
Please see images at bottom of this post
For the mobile devices I tried things like below just for testing but none of them worked...
#media (max-width: 640px) {
#header > a img {
display: none;
}
}
EDIT 14/11/2013 # 01:58GMT
On a 1920x1080 screen it looks kind of okay although there is a big gap between the text and the placeholder image as seen below:
On a 1680x1050 screen it looks roughly how it should take note of where "Semi" is located and compare to the 1920x1080 image from above.
On a 600x600 screen it appears as follows, which as you can see there is a big gap between the placeholder and the left arrow but on the right arrow there is no gap and infact it overflows, as for the text it too is too far to the right.

Type
#media screen and (max-width:640px) {
/* Your specific styles go here */
}
and dont forget to add
<meta name="viewport" content="width=device-width,initial-scale=1.0">
Hope that helps :-)

I see a border around your links, remove from your links:
a{
border:none ;
}
for first issue you can do it with CSS, just remove <img> tag inside <a> tag like this:
<div class="footleft">
<a class="def" href="javascript: void(0);">
</a>
</div>
create image buttons like this:
then set background to <a> tag like this:
#footer .footleft a {
width: 100px;
height: 47px;
display: block;
background: url(path/to/leftarrow.png);
background-position: 0 0;
}
#footer .footright a{
width: 100px;
height: 47px;
display: block;
background: url(path/to/rightarrow.png);
background-position: 0 0;
}
#footer .footleft a:hover , #footer .footright a:hover{
background-position: 0 100%;
}
second issue, I think if you remove position:absolute; from #header .headimage and #footer .footimage it will be okay.
and if your want to centerize headmid and footmid and footmidtwo you have two choices,
First: set fixed width to them and use CSS like this:
#footer .footmid {
top: 50%;
left: 50%;
position: absolute;
font-size: 15px;
width: 292px;
margin-left: -146px;
}
#footer .footmidtwo {
top: 70%;
left: 50%;
position: absolute;
font-size: 15px;
width: 126px;
margin-left: -63px;
}
#header .headmid {
top: 60%;
left: 50%;
position: absolute;
font-size: 15px;
width: 302px;
margin-left: -151px;
}
Second: if you need to have dynamic width you can use this CSS and JQuery:
CSS:
#header .headmid {
top: 60%;
left: 50%;
position: absolute;
font-size: 15px;
}
#footer .footmid {
top: 50%;
left: 50%;
position: absolute;
font-size: 15px;
}
#footer .footmidtwo {
top: 70%;
left: 50%;
position: absolute;
font-size: 15px;
}
JQuery:
var $widthhead = $(".headmid").width();
var $widthfoot = $(".footmid").width();
var $widthfoot2 = $(".footmidtwo").width();
$(".headmid").css("margin-left",$widthhead/2*(-1));
$(".footmid").css("margin-left",$widthfoot/2*(-1));
$(".footmidtwo").css("margin-left",$widthfoot2/2*(-1));
jsFiddle is here

Okay I've tried to filter out all of the irrelevant code for this solution.
See the solution here.
Most of the time, it is best to use relative positioning to fit elements absolutely inside of another element. In your case, with three different strings to fit in a 300x80 window, it's a bit crowded. I tried to place things in a logical position to demonstrate.
By placing a container in the footimage div with relative position, you can then place every element inside the footimage div absolutely relavtive to the footimage div, rather than to the entire page.
For example, what you had:
#footer .footmid
{
position: absolute;
top: 50%;
left: 50%;
}
Will place the div of class footmid at a position 50% of the page height from the top of the page and 50% of the page width from the left of the page:
This will work if every user that visits your page has the exact same resolution, however it causes problems when the don't. Obviously, this isn't a perfect world, so different resolutions will visit your page.
What you can do is use relative positioning!
Basically I tell CSS that instead of moving 50% from the top and left of the window, move 50% from the top and left of the nearest parent element with relative positioning:
You can modify the bottom, left, and right attributes of my fiddle to move the footmid elements within the relative element .footimageContainer that is the same size and in the same position as the .footimage.
As far as your arrows, I wasn't quite sure what you were trying to accomplish; your question was pretty vague, so I simply made them fade out slightly when you mouseover them. Any mouseover/out events can be handled using CSS psuedo-elements.
.element //Native and mouseout
{}
.element:hover //onmouseover
{}
Remember that if you use pseudo-elements, you have to specify the attribute that will be changing in both the native and :hover rules.
.element
{color:red;}
.element
{color:black;}
If you have any additional questions on the arrows, let me know and I'll revise my answer.

http://jsfiddle.net/D8SJD/4/
Instead of using absolute positioning, you can just take advantage of the text-align center and images and text will center automatically.
If you want offset from center, try position:relative, and top, left, right etc and it will move relative to it's central position.
Elements that are display:inline; or display:inline-block; will align according to parents text-align property, in this case text-align:center.
#footer .footimage {
display:inline;
position:relative;
top:-10px;
}
#footer .footmid {
top: 50%;
width:100%;
position: absolute;
font-size: 15px;
}
#footer .footmidtwo {
top: 70%;
width:100%;
position: absolute;
font-size: 15px;
}

As per issue 2, i could be wrong but when targeting the image through the structure of the site
i.e.
headImg a img{...}
The style wouldn't work. But if you add classes to the images the style will work; the case could be that there are some unclosed divs or elements messing with the architecture.
<div class="headimage">
<img class="placeholder" src="http://placehold.it/300x80"/>
</div>
#media screen and (max-width: 640px) {
.placeholder {
display: none;
}
}
JsFiddle here - http://jsfiddle.net/Q5bEb/

Moving label looks good in Firefox - not so good in other browsers How to change?

I wrote a small script to let a label move out of the way everytime the corresponding input field is needed.
Please check it out here: http://jsfiddle.net/5nZWJ/68/
The problem is: it works just as expected in Firefox, but all other browsers I tried (Chromium, Internet Explorer and others) don't keep the bottom-border justified (hard to explain but you will see it if you try it out).
What do I have to change to make this thing in all browsers look like in Firefox?
Thank you in advance!

I have solved your problem. It is now smooth in all browsers: http://jsfiddle.net/5nZWJ/70/
The key is having #formWrapper positioned absolutely from the bottom. This means when the height is increased it expands from the bottom up and doesn't need to recalculate the position from the top.
CSS:
#wrapper {
background-color: lightblue;
height: 110px;
width: 500px;
position:relative; /* Allows absolute figures to be predictable */
}
#formWrapper {
background-color: yellow;
border-bottom: 4px solid red;
bottom: 29px; /* Changed from top and new measurement added */
left: 120px;
height: 57px;
position: absolute;
z-index: 1;
width: 108px;
}
JavaScript:
I removed all lines of code referring to the position, as it no longer needs to be changed or recalculated.

I think this might be related how different browsers count border pixels
http://ejohn.org/blog/sub-pixel-problems-in-css/
(not actually the same problem, but you get some idea)
Instead of using border, I recommend you add a div wrapper around the element, with the background color set to border color and padding set to the border width.

How do I keep a div in the center of the page?

I'm using jQuery to create a "dialog" that should pop up on top of the page and in the center of the page (vertically and horizontally). How should I go about making it stay in the center of the page (even when the user resizes or scrolls?)

I would use
position: fixed;
top: 50%;
left: 50%;
margin-left: -(dialogwidth/2);
margin-top: -(dialogheight/2);
but with this solution and a browsers viewport-size of less than your dialog is, parts of the dialog will be unreachable on top and left sides because they are outside the viewport.
So you have to decide if it's suitable for your dialogs size.
(CSS doesn't know how to calculate, yet. So the little math over there has to be done by you, right now. Therefore your dialog has to be a fixed size which you have to know.)
Edit:
Oh yes, if you want to serve your dialog for the IE6 too, you should do something like this:
#dialog { position: absolute; }
#dialog[id] { position: fixed; }
Since IE6 is not capable of fixed positions and also not capable of attribute-selectors, the IE6 will be the only one who has the position set to absolute. (This will only affect with scrolling behaviour. absolute stays on its place in page and fixed stays on its place in the browser. The rest is similar.)

Check out Infinity Web Design's piece on this.
#mydiv {
background-color:#F3F3F3;
border:1px solid #CCCCCC;
height:18em;
left:50%;
margin-left:-15em;
margin-top:-9em;
position:absolute;
top:50%;
width:30em;
}
This is the CSS they use, and I've tested it out in multiple browsers.
You'll note that the left margin is negative half the width and the top margin is negative half the height. This takes care of the centering, more or less, with absolutely positioning it at 50% top and left.

To put a div horizontally in the middle I always put margin: 0 auto. But it cannot be a floating element and in IE I always needed to put a div around and then give it the property text-align: center, so that the inside div is centered horizontally.

If you know the element's offset dimensions (width/height + padding), you can use this CSS:
elementContainerSelector {
position: fixed; /* You'll of course need to handle browsers that don't support fixed positioning */
top: 0;
left: 0;
width: 100%;
height: 100%;
}
elementSelector {
position: absolute;
top: 50%;
left: 50%;
margin: -[half of offset height]px 0 0 -[half of offset width]px;
}
Hurix's answer works too, and bear in mind the caveats in that answer as well.

Keep margin-left:auto and margin-right:auto