A simple image gallery using only CSS and the :target selector

Back in the old days of web development and when CSS2 got support I always cringed at “CSS only” demos as a lot of them were hacky to say the least. With CSS growing up and having real interaction features it seems to me though that it is time to reconsider as – when you think about it – visual effects and interactivity should be maintained in the CSS rather than in JavaScript and CSS.

With the support we have in new browsers it would be a waste not to use what has been put in. If you have to give all the visual candy to IE6, OK, then you’d have to use a library like jQuery for your effects. But you can have your cake and eat it if you don’t give the shiny to the old browsers out there, but give them a simpler interface and make sure they don’t get what they don’t understand.

So today let’s take a look at an image gallery using the target selector. This has been done before (lightbox example, thumbnail preview example) but I thought it’d be good to explain the details of what is going on.

So here is a screencast of our “CSS only image gallery” in action and you can see it for yourself.

Starting with HTML

We start with HTML that works across all browsers (except for IE < 9, where you need a polyfill to style HTML5 elements):

<section class="gallery">
  <nav>
    <ul>
      <li><a href="#one">One</a></li>
      <li><a href="#two">Two</a></li>
      <li><a href="#three">Three</a></li>
      <li><a href="#four">Four</a></li>
    </ul>
  </nav>
  <article id="one" class="target">
    <figure>
      <img src="http://placekitten.com/g/300/200" alt="Kitten 1">
    </figure>
  </article>
  <article id="two" class="target">
    <figure>
      <img src="http://placekitten.com/g/300/201" alt="Kitten 2">
    </figure>
  </article>
  <article id="three" class="target">
    <figure>
      <img src="http://placekitten.com/g/301/200" alt="Kitten 3">
    </figure>
  </article>
  <article id="four" class="target">
    <figure>
      <img src="http://placekitten.com/g/301/201" alt="Kitten 4">
    </figure>
  </article>
</section>

Without any CSS this would just show all the kitten images in a vertical row and the links would point to them. This works, and should be more than enough for the IE6 users out there.

For browsers that support newer CSS, however, we can turn this into our gallery in a few easy steps:

Step 1: Position the articles

To make sure we don’t give IE older than 9 any CSS it chokes on, we can wrap all the selectors in a simple media query (in this case checking that the window is at least 400 pixels wide):

@media screen and (min-width: 400px) {
  ... all the good stuff ...
}

We then can give the gallery dimensions and an overflow of hidden to make sure that elements positioned outside of it will not be shown. We also position it relative so that every positioned child element will be positioned relatively to it:

.gallery {
  position: relative;
  height: 280px;
  width: 340px;
  overflow: hidden;
}

Then we position all the target elements absolutely in the gallery with 320 pixels to the left. This hides them off screen as we hide the overflow:

.target {
  position: absolute;
  top: 60px;
  left: -320px;
  height: 220px;
  width: 300px;
}

Now in order to show the image when the link to it was clicked we use the :target selector. This one assigns the CSS to the element when it was targeted – either by activating a link to it in the document or from the URL when the page loaded. With this pseudo selector, we override the left setting and move it to 20 pixels, thus showing the image.

.target:target {
  left: 20px;
}

You can try this out for yourself:

To make this smoother, all we need to do is to add a CSS transition to the target styles. Now all the changes to the styles will happen smoothly during a second rather than immediately.

.target {
  position: absolute;
  top: 60px;
  left: -320px;
  height: 220px;
  width: 300px;
  -webkit-transition: 1s;
     -moz-transition: 1s;
      -ms-transition: 1s;
       -o-transition: 1s;
          transition: 1s;
}

Again, see it in action and play with it.

That is all there is to it – the rest of the effects are just different variations of the same trick – animating opacity from 0 to 1 or CSS transitions.

Target selectors can be a very powerful trick. The main issue they have though is that the page scrolls to the target, so if there is a big distance between the link and the target you’ll get unsightly jumps.

View full post on Mozilla Hacks – the Web developer blog

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