Conditional HTML classes
Written byPhuoc Nguyen
Created
06 Sep, 2022
The previous post introduces the technique to load styles for a given IE version.
Let's revisit how the styles are organized:
html
<link href="styles.css" rel="stylesheet" />
<!--[if IE 8]>
<link href="fix-ie8.css" rel="stylesheet" />
<![endif]-->
<!--[if IE 9]>
<link href="fix-ie9.css" rel="stylesheet" />
<![endif]-->As we can see, the approach adds one more HTTP request. For example, IE 8 will load
`styles.css` and `fix-ie8.css` files as separate requests.
We can reduce the number of requests by using the conditional comments for the root `html` element:html
<!--[if lt IE 7]><html class="ie6"><![endif]-->
<!--[if IE 7]><html class="ie7"><![endif]-->
<!--[if IE 8]><html class="ie8"><![endif]-->
<!--[if IE 9]><html class="ie9"><![endif]-->
<!--[if (gt IE 9)|!(IE)]><!--><html><!--<![endif]--></html>The root
`html` element will have an additional CSS class depending on the current version of IE which visitors use. For example, IE 9 browser will add `ie9` CSS class.
The styles are now combined into a single sourcehtml
<link href="all-styles.css" rel="stylesheet" />It contains the fixes for different IE versions:
css
.card {
background: rgba(0, 0, 0, 0.5);
}
/* Background with opacity is only available on IE 9 and later */
.ie6 .card,
.ie7 .card,
.ie8 .card {
background: #ccc;
}The issue of the number of HTTP requests is resolved. However, the styles now contain many duplication codes. We can fix the issue by adding more CSS classes to the
`html` element:html
<!--[if lt IE 7]><html class="lt-ie7 lt-ie8 lt-ie9"><![endif]-->
<!--[if IE 7]><html class="lt-ie8 lt-ie9"><![endif]-->
<!--[if IE 8]><html class="lt-ie9"><![endif]-->
<!--[if gt IE 8]><!--><html><!--<![endif]--></html>Additional styles for
`card` on IE 6, 7, 8 now can be combined into a single class declaration:css
.lt-ie9 .card {
/* Styles for IEs before 9 */
}
Questions? 🙋
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Phước Nguyễn