How to fade text out vertically, similar to Amazon's product descriptions

Question

I am trying to to fade a block of text from black on the first line to light grey on the last line. I noticed that Amazon does this with their product description. I tried looking at the CSS code and I couldn't see anything there, I suspect it is achieved with javascript.

My question is: How would I go about emulating a similar vertical fading effect on a textblock of my own?

Answer 1

Here is a completely cross-browser solution generated by http://www.colorzilla.com/gradient-editor/:

DEMO: http://dabblet.com/gist/3511782

CSS:

#container {
    width: 400px; /*width of text box*/
    height: 200px; /*height of text box*/
    border: 2px solid black; /*it needs some kind of border to look good*/
    overflow: hidden; /*necessary to cut off text without scrollbars. alternatively you can use overflow: auto; or overflow: scroll; to show a scrollbar, but you'll have to tweak the #fader box*/
    position: relative; /*positioning so that #fader can be relative to this*/
}
#fader {
    height: 100px; /*from where it starts to fade to where it ends*/
    position: absolute; /*so it can overlap the #container*/
    width: 400px; /*has to be the same as #container*/
    margin-top: 25%; /*position it right at the bottom of the #container*/
    /* IE9 SVG, needs conditional override of 'filter' to 'none' */
    background: url(data:image/svg+xml;base64,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);
    background: -moz-linear-gradient(top,  rgba(255,255,255,0) 0%, rgba(255,255,255,1) 100%); /* FF3.6+ */
    background: -webkit-gradient(linear, left top, left bottom, color-stop(0%,rgba(255,255,255,0)), color-stop(100%,rgba(255,255,255,1))); /* Chrome,Safari4+ */
    background: -webkit-linear-gradient(top,  rgba(255,255,255,0) 0%,rgba(255,255,255,1) 100%); /* Chrome10+,Safari5.1+ */
    background: -o-linear-gradient(top,  rgba(255,255,255,0) 0%,rgba(255,255,255,1) 100%); /* Opera 11.10+ */
    background: -ms-linear-gradient(top,  rgba(255,255,255,0) 0%,rgba(255,255,255,1) 100%); /* IE10+ */
    background: linear-gradient(to bottom,  rgba(255,255,255,0) 0%,rgba(255,255,255,1) 100%); /* W3C */
    filter: progid:DXImageTransform.Microsoft.gradient( startColorstr='#00ffffff', endColorstr='#ffffff',GradientType=0 ); /* IE6-8 */
}

HTML:

<div id="container"><div id="fader">&nbsp;</div>
Text goes here
</div>

For IE9 support, you need a conditional comment in the head:

<!--[if gte IE 9]>
  <style type="text/css">
    .gradient {
       filter: none;
    }
  </style>
<![endif]-->

And in case you were wondering, the way amazon does it is very similar: http://pastebin.com/jkq3nbDJ

Answer 2

So what you have is an absolutely positioned div (.fade-out in my example below) the height of the fade effect with an background png of a vertical fade or a css3 gradient.

HTML

<div class="description">
    <p>Text Here</p>
    <div class="fade-out"></div>
</div>

CSS

.description { 
    position: relative;
    width: 100%;
}
.fade-out {
    position: absolute;
    bottom: 0;
    left: 0;
    right: 0;
    z-index: 2;
    height: 30px;
    background: ...
}