Develop Reference

when a div is not displayed, forget this css rule

I have a situation where I have 3 divs :
- Menu - Header (#rt-top-surround)
- Showcase (#rt-showcase)
- Main Body content (#rt-mainbody-surround)
The Menu is 'sticky' with position: fixed. Therefor I have to move the div that is rendered below it with padding (padding-top: 120px; margin-bottom: -120px;).
The problem that I run into is that on some pages the second DIV is #rt-mainbody-surround. (Than this div is rendered properly.)
But on other pages I have #rt-showcase (that displays some promotional images) as second DIV followed by the main body DIV.
So what I would need to implement is a rule that not adds the padding & margin on the rt-mainbody-surround div when the rt-showcase is displayed. And I'm not wether to do this with Javascript or with PHP and how to accomplish this.
I've made an illustration to show what I exactly mean.
Hope anyone can help me out here! Thanks!
Illustration

If I understand the question correctly you want a margin below a specific div only if another div isn't actively visible. The best way to handle this is to add a bottom margin to the top div and negative margin to the div below it (that can be shown and hidden). The css for that is:
.top {
margin-bottom: 20px;
}
.middle {
margin-top: -20px;
}
Sometimes a picture is worth more than some code though so I created a fiddle here. Enjoy!

scroll and position: fixed inside overflow: scroll div

I have a position: fixed div besides a div with long text inside a div with overflow: scroll. I want the text to scroll even if my cursor is hovering over the fixed div (which is the normal behavior when the window would be the scrolling element).
I made a fiddle: http://jsfiddle.net/jM2Eh/1/
I basically want the text to scroll while scrolling hovering over the red box.
UPDATE: I am using Twitter bootstrap in this particular case and updated the fiddle accordingly.
If JavaScript is needed for that, that would also be ok.
UPDATE2: I also tried this solution, but that causes weird flickering effects:
http://jsfiddle.net/jM2Eh/16/

Have you tried using padding-left on your text node instead of using two columns?
http://jsfiddle.net/j5BLm/15/
.text {
padding-left: 50%;
}
Another possible solution is to use pointer-events: none if you don't care about IE:
http://jsfiddle.net/codedigger/jM2Eh/18

Rotation of CSS arrow and javascript toggling

I have two div banners that have corresponding CSS arrows. When the banners are clicked, the javascript toggles between revealing and hiding the text underneath. Likewise, the respective arrows rotate down when the text is revealed and back up when the text is hidden.
Now, I want my first div banner to be revealed automatically when the page first loads. However, when I drew my CSS arrows, due to the padding of the div, I can't get the arrow in the first div to be the same as the arrow in the subsequent div(s) and line up properly.
http://jsfiddle.net/nVuQ2/1/
I've tried messing with the placement of the arrow:
.tri0 {
margin-left: 20px;
margin-top: 5px;
}
but the best I can do is push the tri0 arrow up to the padding of the h3 tag and it won't go any farther.
Is there a way that I can set a toggle flag in the toggleClass to make it say that the first div banner is already toggled and subsequent clicks make it un-toggle?

Your issue happens because of the border of your tris elements. You are displaying different borders in each one of your elements, this will make them appear in different ways.
So basically I set them with the same borders values, the same rotation, and when your page first load it toggles your div and show your first message.
Note that is not necessary to have two different classes to toggle your element state, once that they are equal.
Check in the Fiddle.
Not sure if this is the solution that you wanted. But I hope that helps you.
Thanks.

Try using absolute positioning instead of floating, this way you can ensure the arrows are always aligned in the middle. You'd set parent div to position:relative, and arrows to position:absolute;
The code will look like this -
.slide0, .slide1 {
position:relative;
}
.tri0, .tri1 {
position:absolute;
top:0;
bottom:0;
margin:auto 0;
}
.tri0 {
right:5px;
}
.tri1 {
right:10px;
}
EDIT: Whoops, I realised I didn't compensate for the rotated arrow. Because the 10px border makes it effectively 10px wide, position .tri1 with right:10px instead. Updated code above, and update fiddle here.
Updated Fiddle

CSS/JS content scroll UP instead of down

I'm building a site with the navigation bar stretching across the entire site and it's fixed.
Under the navigation bar there is an image, a background image, which is set as a cover. And under the image is the main content.
When you scroll down, the navigation bar covers the image from top to bottom and the main content is now visible, effectively scrolling in a downwards fashion. I would like to "reverse" it. So the navigation is still fixed with the cover image under it but this time, when you scroll down the main content comes up and covers the image from bottom to top. So when you scroll down, the main content scrolls up.
Let's say my image has a 1 at the top and a 2 at the bottom. So, normally when you scroll down the navigation bar covers the image from top to bottom the 1 will disappear and the 2 will be visible until that is also covered. The effect I'm looking for would make the 2 disappear and the 1 would remain in the same place until it is covered by the main content.
I looked into parallax but I'm not sure if that's the right thing to go with. And I have no idea how to do achieve this effect.
Hopefully you'll understand what I'm trying to do here. If you need any more info then just let me know.
Thanks in advance.
EDIT
The effect can be seen on the abduzeedo frontpage

You need the image to be "attached" to the background ?
If so, cannot you just fix it to the background ?
body {
background-attachment:fixed;
}
Source: http://www.w3schools.com/cssref/pr_background-attachment.asp
https://developer.mozilla.org/en-US/docs/Web/CSS/background-attachment
Note: Be careful using W3Schools, their information is often incorrect, see here.

Here's an example with an img element.
Demo
code view
The basic HTML layout:
<nav></nav>
<img src="/image.ext" class="scrollup" />
<div class="main"></div>
Your nav will be positioned fixed, as you said. The image also needs fixed positioning. We set its z-index to -1 to make sure it's covered up.
img {
position: fixed;
width: 100%;
z-index: -1;
top: 20px; left: 0;
}
The main element is positioned relatively. Because our nav and image both have fixed positioning, the top value is relative to the top of the viewport. 100% means that .main starts as soon as we start scrolling.
.main {
background: white;
position: relative;
top: 100%;
}

Get rid of useless scroll bars on fancybox iframe

I have some content I want to show in iframe with fancybox. When I use it, it pops up with horizontal and vertical scroll bars even though all the content is inside of it. Inspecting it in Firefox shows that when I click on html everything is inside but there is a little left over that is outside of the highlighted box. The next level up is iframe.fancybox-iframe which includes the scroll bars. I looked at the css and that has padding and margins set to zero so I don't know why the scroll bars are there. Right now as far as options I just have autoSize:false. All I have inside the body of the page I want to show is a form.

If anyone wonders which class name to use
.fancybox-inner {
overflow: hidden !important;
}
And if you found a small white background you can reset it using
.fancybox-skin {
background: inherit;
}

Try adding this to the css:
.style{
overflow: hidden;
}
If it didn't help, please post your HTML and CSS.