CSS Best practice

CSSBEST PRACTICE

Best practice

“Best practice” is a very loose and often poorly defined term.

“Best practice” often comes down to personal opinion.

“Best practice” can depend on the team environment you are

working in.

“Best practice” may also depend on the applications you have to

work with.

Your personal “best practices” may change radically over time!

With that in mind, here are some tips that may help you when

setting up CSS files in the future.

Applying CSS

1. Avoid using inline styles as they are hard to maintain and

increase file size.

<body><h2 style=“color: red;”>! Heading here</h2>

Avoid

2. Avoid using header styles as they are also hard to maintain

and increase file size.

<style>p { color: red; }

</style>

Avoid

3. Avoid using @import within the HTML as this will slow down IE

browsers.

<style>@import "a.css";

</style>

Avoid

4. Avoid using multiple CSS files, or combine all CSS files

before final production.

<link rel="stylesheet" href="reset.css"><link rel="stylesheet" href="grids.css"><link rel="stylesheet" href="text.css"><link rel="stylesheet" href="modules.css"><link rel="stylesheet" href="colors.css">

Avoid

Writing CSS rules

5. Use multiple declarations where possible

p{! margin: 0 0 1.5em;! background: green;}

6. Use multiple selectors where possible

h1, h2, h3, h4, h5{! color: #666;! margin: 0 0 .5em;}

7. Use shorthand properties where possible

body{margin-top: 20px;margin-right: 10px;margin-bottom: 20px;margin-left: 10px;

}

body { margin: 20px 10px; }

Avoid

Preferred

8. Avoid !important as it is often unnecessary - especially when you understand the cascade.

p{! margin: 0 !important;}

Avoid

9. Avoid complex selectors (taxing for browsers). Try to be

only as specific as needed.

#navigation ul li a { margin: 0; }

#navigation a { margin: 0; }

Avoid

Preferred

10. Avoid universal selectors.

.nav * { margin: 0; }

Avoid

11. Avoid qualifying selectors as this is often unnecessary.

div.nav { }

.nav { }

Avoid

Preferred

12. Avoid IE-proprietary filtersas they slow page performance.

filter:Alpha(Opacity=40);-ms-filter: "Alpha(Opacity=40)";

Avoid

13. Avoid IDs. Where possible use classes instead.

#header { ... }

.header { ... }

Avoid

Preferred

14. Try not to use too many font-size declarations.

h1 { font-size: 200%; }.nav { font-size: 80%; }.widget { font-size: 70%; }.intro { font-size: 110%; }.sidebar { font-size: 85%; }

Avoid

Optimisation

15. Some people like to use a CSS minifier to reduce your

overall CSS file size:

http://refresh-sf.com/yui/

16. Optimise images as much as possible

17. Where possible, combine images into sprites.

18. If possible, use CSS3 rules instead of images to reduce

server requests and page size.

p { background: url(round-corners.png); }

p { border-radius: 10px; }

Avoid

Preferred

Russ WeakleyMax Design

Site: maxdesign.com.auTwitter: twitter.com/russmaxdesignSlideshare: slideshare.net/maxdesignLinkedin: linkedin.com/in/russweakley

Education

CSS Best practice