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Advanced CSS Troubleshooting
The document is a guide on advanced CSS troubleshooting techniques presented by Denise R. Jacobs at the CSS Summit 2010. It outlines four key steps for effective troubleshooting: laying a solid foundation, targeting styles efficiently, resolving browser-specific bugs, and handling float issues. The guide also emphasizes best practices in CSS such as annotation, optimization, and leveraging specificity for better performance.
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Advanced CSS Troubleshooting
- 1. Advanced CSS Troubleshooting or How to become a Super CSS Detective in 4 Easy Steps Denise R. Jacobs CSS Summit 2010
- 2. Who, Me? CSSDetectiveGuide.com InterActWithWebStandards.com 2
- 3. CSS De-what? • Preventive/defensive coding – Focused & efficient • Can quickly and easily solve problems when they come up 3
- 4. I can haztrubbleshootin? Strong troubleshooting skills are one of your best allies in solving CSS “mysteries”…and they also make you feel like a badass. 4
- 5. The 4 EasySteps 1) Lay the foundation 2) Target your styles 3) Squash browser bugs 4) Clear float issues 5
- 6. 1) Lay the Foundation 6 http://www.flickr.com/photos/pgoyette/2280685630/
- 7. Why? A solid CSS foundation creates an environment where preventing and detecting problems is easier. 7
- 8. How to layit down 1) Annotate & Optimize • Markup • CSS 2) (Re)Set the Mood • CSS reset review • DIY 8
- 9. Annotate Your Markup begin with <!-- #id or .class name --> end with <!-- /end #id or .class name --> or, alternatively <!-- / #id or .class name --> 9
- 10. Annotate Your Markup Example: <div id="content"> <div class="promo"> ... </div><!-- /end .promo --> </div><!-- /end #content --> 10
- 11. Why Annotate YourMarkup? Helps you keep track of the element beginning and end, and helps you identify the pieces faster. 11
- 12. Annotate Your CSS:Macro-Optimize /* Comments are good, mmkay? */ Notation is your friend. For: • Overriding styles • Creating stylesheet sections • Listing the color scheme • Resources and contact info. 12
- 13. Annotate Your CSS:Macro-Optimize /* made by you on some date */ /* section of the stylesheet */ p { border-color: #cf0; border-color-bottom: #ccc; /*this property overrides the previous one */ } 13
- 14. Why Macro-Optimize? Solo: Helps you remember your intentions with extra properties when you come back to your code. With Folks: Helps your colleagues understand your intentions when working with your code. Ergo: Saves time! 14
- 15. Micro-Optimize Your CSS:Length Less is more: • Use shortest properties and values • Avoid duplicate properties • Use shorthand properties • Condense values and units • Avoid multiple lines and indenting 15
- 16. Micro-optimize Your CSS:Speed Up the efficiency: • ID selectors are speedier than element or universal • Drop element qualifiers • Ditch descendent selectors when and where you can 16
- 17. Why Micro-Optimize? • Cuts down file size • Speeds up page load time • Encourages best practices 17
- 18. Micro-Optimization in Action Example: #sidebar { background: #fff url(bg.png) repeat-x 0 0; font: normal 1.33em/1.33 Georgia, serif; border: 1px solid red; margin: 10px 20px; padding: .1em; } 18
- 19. Reasons to Reset By deliberately establishing an element’s properties, you can: • Better control the elements on the page • More quickly determine the source of problems when they arise 19
- 20. CSS Reset All-Star:Eric Meyer’s Pro’s –One of the most popular, well thought out –Neutralizes almost every element Con’s –Can be too far-reaching –Extra work to establish the values for the elements you want 20 http://meyerweb.com/eric/tools/css/reset/
- 21. Make Your OwnReset Why DIY? • You can determine exactly which elements you want to reset • May save on reestablishing properties • You know exactly what is changed and why you changed it • Problems will be that much more obvious 21
- 22. Top Properties toReset • Margin and padding • Borders, especially on linked images • Link text underlining • Vertical alignment • Font size and line-height 22
- 23. 2) Target Your Styles 23 http://www.flickr.com/photos/blip/139087426/
- 24. Why? Having a plan for targeting elements helps speed and efficiency – in both creating and fixing styles. 24
- 25. How to Hitthe Mark 1) Technique 2) Specificity 3) Advanced Selectors 25
- 26. One Targeting Technique My favorite: outline: 1px solid red; Why? • outline does not add to dimensions of the element • Color names used only for troubleshooting 26
- 27. Specificity Rules! Using specificity, you can create selectors that will zero right in on your desired element(s), but you’ve got to do it by the rules. A little review: 1. Weight rules 2. Specificity tips and guidelines 27
- 28. Super Simplified Specificity The more specific the selector is, the higher the specificity #id: can only be one on the page = high specificity (100) .class: can be multiple, but not everywhere = medium specificity (10) element: lots on the page = low specificity (1) * : everything on the page = no specificity (0) 28
- 29. Some Specificity Guidelines • Don’t rely too heavily on specificity – leverage as many reusable selectors as possible • Use the cascade and source order so that you don’t have to get too specific • Trust specificity over source order in terms of which style will win and get applied 29
- 30. Targeting with AdvancedSelectors The right selector will help you achieve targeting nirvana, so it’s important to know which selectors you can use now. Let’s peek at: • CSS2 Selectors • CSS3 Selectors • Their browser support 30
- 31. Advanced CSS2 Selectors • Universal (ie7/8 – yes) • Child (ie7/8 – yes) • Sibling/Adjacent (ie7 no, ie8 – yes) • Attribute (ie7/8 – yes) • Pseudo elements (ie7/8 – no) – ::before – ::after • State pseudo-classes, v2.1 – :first-child (ie7/8 – yes) – :hover (ie7/8 – yes) – :active (ie7/8 – yes) – :focus (ie7/8 – no) – :lang (ie7/8 – no) 31
- 32. CSS2 Selector Support 32 http://www.quirksmode.org/compatibility.html
- 33. Advanced CSS3 Selectors • General sibling • Attribute substrings • State pseudo-classes, v3.0 –:enabled –:disabled –:checked –:selection • Target pseudo-classes • Negation pseudo-class 33
- 34. Advanced CSS3 Selectors,contd. • Structural pseudo classes – :root – :nth-child(n) – :nth-last-child(n) – :nth-of-type(n) – :nth-last-of-type(n) – :last-child – :first-of-type – :last-of-type – :only-child – :only-of-type – :empty 34
- 35. CSS3 Selector Support 35 http://www.findmebyip.com/litmus
- 36. Advanced Selectors: SomeUsage Tips • All of the CSS2 selectors are supported by the modern browsers, and almost all of the CSS3 ones are, so use them! • It’s easy to target styles away from the IEs, but target them to the IEs with simpler combinator selectors • There are “hacks” to target styles to specific browsers, other than the IEs 36
- 37. 3) Squash Browser Bugs 37 http://www.flickr.com/photos/slappytheseal/3687999392/
- 38. Dealing with IE6(Still? Yes, still.) Whether it’s by force or by choice, you need to know how you are going to deal with IE6 until it’s completely gone. Approaches: • Kick it to the curb • Display tolerant indifference • Show some love: be graceful in your degradation 38
- 39. IE6: Go home! 39 http://www.flickr.com/photos/robotjohnny/3629069606/
- 40. IE6, get stuffed. 40 http://tumblr.9gag.com/post/285107173
- 41. IE6? I justwon’t support that. 41
- 42. IE6? Meh. 42 http://www.flickr.com/photos/untitled13/83391194/
- 43. Serve Up SomeStripped-Down Style Universal IE6 stylesheet (philosophy) (example) Universal IE6 stylesheet: http://code.google.com/p/universal-ie6-css/ 43 http://browsesad.com
- 44. Limit Your Support 44 http://gowalla.com
- 45. Show an oldIE browser some love 45 http://www.flickr.com/photos/brunkfordbraun/391876102/
- 46. Graceful IE6 Degradation • Serve IE6 targeted properties served by conditional comments – display: inline – zoom: 1 • Use the * html hack 46
- 47. Gettin’ Buggy WithIt Despite your best efforts towards clean, efficient, optimized code, browsers will always have issues that throw a wrench in the works. The Line-up: 1) IE7 & IE8 2) Firefox 3) The Webkits 4) Opera 47
- 48. IE7 is colorbuggin’ color and background-color with rgba The problem: An rgba color is correctly set to override the rgb for the IEs , but the rgb color doesn’t show up at all. 48
- 49. IE7 is colorbuggin’ The solution: • Use the shorthand property background instead of background- color OR • Use a hexidecimal color instead of rgb, and then continue the override with rgba. 49
- 50. IE7 is colorbuggin’ Example: div { background: rgb(200, 54, 54); /* fallback color */ background: rgba(200, 54, 54, 0.5); } OR div { background-color: #fd7e7e; background-color: rgba(255,0,0,0.5); } 50
- 51. IE7 & IE8are both buggin’ @font-face super bullet-proofing The problem: @font-face doesn’t work, even with the proper normal syntax. What gives? 51
- 52. @font-face bullet-proofing, #1 @font-face { font-family: 'Graublau Web'; src: url('GraublauWeb.eot'); src: local('☺'), url('GraublauWeb.woff') format('woff'), url('GraublauWeb.ttf') format('truetype'); } 52
- 53. @font-face bullet-proofing, #2 @font-face { font-family: 'Graublau Web'; src: url('GraublauWeb.eot'); } @font-face { font-family: 'Graublau Web'; src: local('☺'), url('GraublauWeb.woff') format('woff'), url('GraublauWeb.ttf') format('truetype'); } 53
- 54. Get Your WebkitBug On @font-face bold and italics “bug” The problem: Applying font-weight:bold or font- style: italic to @font-face'd text doesn’t work. 54
- 55. Get Your WebkitBug On The solution: Add the value normal to font weight, style, and variant in the @font-face declaration to set a baseline. 55
- 56. Get your @font-face+ faux variations Example: @font-face { font-family: 'Graublau Web'; src: url('GraublauWeb.eot'); src: local('☺'), url('GraublauWeb.woff') format('woff'), url('GraublauWeb.ttf') format('truetype'); font-weight:normal; font-style:normal; font-variant:normal; } 56
- 57. Firefox? Buggin’. The Outline Overflow Bug The problem: Firefox will draw an outline around the content of an element that has overflowed its boundaries rather than around the element’s actual set dimensions. 57
- 58. Firefox? Buggin’. The Outline Overflow Bug A solution: Use border instead and adjust the dimensions of the element. 58
- 59. An Ode toOpera Bugs Hiding elements bug The problem: When hiding elements offscreen for image replacement, etc. em units are not recognized. 59
- 60. An Ode toOpera Bugs The solution: Use px instead of em Example: h2 {margin-left: -4999px ;} 60
- 61. 4) Clear Float Issues 61 http://www.flickr.com/photos/elisfanclub/1132147711/
- 62. Clear Float Issues 1) Problems with overflow: hidden 2) Problems with Clearfix 3) Solutions and Alternatives 62
- 63. Floats: overflow: hiddenIssues Although this is almost everyone’s favorite float-clearing technique, there can be problems with: • Hiding content with no scrollbars when browser window is smaller than container • Interference with margins, borders, outlines, and absolutely-positioned PNGs • Application of CSS3 properties, such as box-shadow, text-shadow & transform 63
- 64. overflow: hidden Issues Example: div.container { border: 1px solid #000000; overflow: hidden; } 64
- 65. overflow: hidden Alternative Example: div.container { border: 1px solid #000000; overflow: auto; /* hidden & scroll also work*/ width: 100%; /* some width or height required */ } 65
- 66. Clearfix Issues Be aware of support: • Neither IE6 nor IE7 support the :after pseudo- class Be mindful of the generated content: • Sometimes the generated period can be a problem Remember where to put it: • Apply .clearfix to the element containing the floats, so that the cleared content is generated after it 66
- 67. The Top Clearfix Example: .clearfix:after { visibility: hidden; display: block; font-size: 0; content: " "; clear: both; height: 0; } .clearfix { display: inline-block; } /* ie for mac hack removed for readability */ 67
- 68. Clearing Floats Alternatives FnE still a viable option: • Contains and clears Potential issue: • Watch for how it affects the rest of the page layout and structure 68
- 69. Future Hope ForPage Layouts CSS3 and HTML5 FTW! • CSS3: flexible box-model, columns and box-sizing • HTML5: <head>,<section>, and <footer> 69
- 70. Recap Taking all ofthese steps: 1. Lay the foundation 2. Target your styles 3. Squash browser bugs 4. Clear float issues Will yield: 1. Code that is easier to read and find problems in 2. Speed of use and in use 3. Finding solutions faster 70
- 71. And you’ll become… …onebaaad CSS detectin’ mutha! 71
- 72. Questions?...Answers? 72 http://www.flickr.com/photos/
- 73. Resources http://delicious.com/denisejacobs/ CSSsummit2010/ 73 http://www.flickr.com/photos/aarronwalter/4629076165/
- 74. Shameless Self-Promotion #1 The CSS Detective Guide CSSDetectiveGuide.com twitter.com/cssdetective Get 35% off at PeachPit.com with the discount code “DETECTIVE” 74
- 75. Shameless Self-Promotion #2 InterAct With Web Standards: A Holistic Approach to Web Design InterActWithWebStandards.com twitter.com/waspinteract Get 35% off at PeachPit.com with the discount code “INTERACT” 75
- 76. Thank You! denisejacobs.com denise@denisejacobs.com twitter.com/denisejacobs slideshare.net/denisejacobs 76 http://www.flickr.com/photos/aarronwalter/4629076165/
- 77. And that’s awrap! 77