CSS Best practice
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This document provides tips for best practices when writing CSS code. It recommends avoiding inline styles, header styles, multiple CSS files, and !important. It also recommends using shorthand properties, avoiding universal selectors and IDs when possible, optimizing images, and using CSS3 properties instead of images. In summary, the document outlines techniques for writing efficient, well-structured CSS code to improve performance and maintainability.
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CSS Best practice
- 3. “Best practice” is a very loose and often poorly defined term.
- 4. “Best practice” often comes down to personal opinion.
- 5. “Best practice” can depend on the team environment you are working in.
- 6. “Best practice” may also depend on the applications you have to work with.
- 7. Your personal “best practices” may change radically over time!
- 8. With that in mind, here are some tips that may help you when setting up CSS files in the future.
- 9. Applying CSS
- 10. 1. Avoid using inline styles as they are hard to maintain and increase file size. Avoid <body> <h2 style=“color: red;”> ! Heading here </h2>
- 11. 2. Avoid using header styles as they are also hard to maintain and increase file size. Avoid <style> p { color: red; } </style>
- 12. 3. Avoid using @import within the HTML as this will slow down IE browsers. Avoid <style> @import "a.css"; </style>
- 13. 4. Avoid using multiple CSS files, or combine all CSS files before final production. Avoid <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">
- 15. 5. Use multiple declarations where possible p { ! margin: 0 0 1.5em; ! background: green; }
- 16. 6. Use multiple selectors where possible h1, h2, h3, h4, h5 { ! color: #666; ! margin: 0 0 .5em; }
- 17. 7. Use shorthand properties where possible body { Avoid margin-top: 20px; margin-right: 10px; margin-bottom: 20px; margin-left: 10px; } Preferred body { margin: 20px 10px; }
- 18. 8. Avoid !important as it is often unnecessary - especially when you understand the cascade. p Avoid { ! margin: 0 !important; }
- 19. 9. Avoid complex selectors (taxing for browsers). Try to be only as specific as needed. Avoid #navigation ul li a { margin: 0; } #navigation a { margin: 0; } Preferred
- 20. 10. Avoid universal selectors. Avoid .nav * { margin: 0; }
- 21. 11. Avoid qualifying selectors as this is often unnecessary. Avoid div.nav { } .nav { } Preferred
- 22. 12. Avoid IE-proprietary filters as they slow page performance. Avoid filter:Alpha(Opacity=40); -ms-filter: "Alpha(Opacity=40)";
- 23. 13. Avoid IDs. Where possible use classes instead. Avoid #header { ... } .header { ... } Preferred
- 24. 14. Try not to use too many font-size declarations. h1 { font-size: 200%; } Avoid .nav { font-size: 80%; } .widget { font-size: 70%; } .intro { font-size: 110%; } .sidebar { font-size: 85%; }
- 25. Optimisation
- 26. 15. Some people like to use a CSS minifier to reduce your overall CSS file size: http://refresh-sf.com/yui/
- 27. 16. Optimise images as much as possible
- 28. 17. Where possible, combine images into sprites.
- 29. 18. If possible, use CSS3 rules instead of images to reduce server requests and page size. Avoid p { background: url(round-corners.png); } p { border-radius: 10px; } Preferred
- 30. Russ Weakley Max Design Site: maxdesign.com.au Twitter: twitter.com/russmaxdesign Slideshare: slideshare.net/maxdesign Linkedin: linkedin.com/in/russweakley