What we’re creating is basically a cool transparency overlay effect that closely resembles anaglyph stereoscopic 3D images. To use the effect in our web designs we’ll of course build it with CSS, but the main consideration is to keep everything neat and true in our markup, without any repeated markup. Therefore, we don’t want to use anything like this:
Using a span would be handy to provide us with something to target our CSS to and style up the two words to overlay on top of each other, but when read aloud in the markup, and when viewed without CSS styling it’s simply wrong. With the effect being more presentational or aesthetic than it is part of the content, we need to ensure it’s semantically correct.
The :after class and content property
Here’s where the content property and the :after pseudo element comes into play. The :after pseudo element allows us to insert a snippet of content after the targeted header and adding our extra text in the CSS content property keeps our markup free of any wordage that shouldn’t be there, ensuring that it can’t be seen or read by screenreaders, RSS readers or search bots.
What’s more, we can also use the content property to not only manually write in some text, but also ask it to take the content from a specific attribute such as the title. This provides a dynamic solution that could be implemented in Wordpress, but it’s not 100% ideal as it doesn’t stay true to the natural use of the title attribute. The title attribute should provide more information about the element, rather than regurgitate the same text.
Styling it up
So far we’ve just got two of the same word placed side by side. Let’s add some extra CSS stying to overlay the two and bring in some colour.
First up, the H1 element is converted to inline and positioned relatively to allow the absolute positioning of the generated text to work. Next up, the font styling is specified as 200px Helvetica with some letter-spacing tweaks to tighten up the example. The text is then coloured using RGBa, which allows the aplha transparency to be set so that when overlayed the underlying colour will show through. The generated text from the content property is also given some styling, specifically the text is positioned absolutely to sit slightly offset from the original at 10px and 5px on each axis, and is switched to red to contrast against the blue.
The final anaglyphic effect
<h1>Hello</h1>
h1 {
display: inline;
position: relative;
font: 200px Helvetica, Sans-Serif;
letter-spacing: -5px;
color: rgba(0,0,255,0.5);
}
h1:after {
content: "Hello";
position: absolute; left: 10px; top: 5px;
color: rgba(255,0,0,0.5);
}