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css sibling operator (folding divs)

I have been fiddling with CSS a lot in my current client project. I am no ninja yet but I am getting hold of the elementary stuff at least. Today I made one radio button show a div and another one hide it. To be able to do this you need to know about the sibling operator ~ that is used to find an element matching the selector that is after the main rule. Consider this markup snippet:

<input checked="checked" class="fold_open" type="radio" value="open" />
<input class="fold_closed" type="radio" value="closed" />
<div class="foldee">
  <!-- some awesome markup here -->
</div>

Two radio buttons with classes fold_open and fold_closed respectively. One div with the class foldee. To make the div fold when fold_closed selected and unfold when fold_open is selected - add this css:

.fold_open:checked ~ .foldee {
  display: block;
}

.fold_closed:checked ~ .foldee {
  display: none;
}

This means that when the class fold_open is checked (works for radio buttons and check boxes) its sibling foldee will be shown and when fold_closed is checked it will disappear. A tricky thing with the sibling selector is that it only finds elements after its left hand operator. So if you want to hide something above you will have to rearrange your markup and use inspired styling to make it show up in the right place.

This will probably not work in some browsers mayhaps causing a problem depending on your use case and your user base. For a version that is guaranteed to work you will have to write some scripts instead. The amount of code with something like jquery is about the same. But I found it a bit more elegant to do it with css.

The car in the photo is an Alfa Romeo 1900 CSS and it is just here for looks. Find a good photo about css….. It was shot by flickr user Henry Figueroa.

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