CSS for the Next Billion Users. CSSDay.NL 2018

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Letitia Griffin
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1 CSS for the Next Billion Users CSSDay.NL 2018

2 Ire Aderinokun

3 E + Rey

4 !

5 Who are the Next Billion Users?

8 Until now, developing for the web = developing for users like you

9 Until now, developing for the web = developing for users like you

11 In 1995, The average cost of computers was ~ USD 10,000

12 In 1995, Only 0. 4% of the global population had access to the internet

13 In 1995, Access to assistive technologies was essentially non-existent

15 Techno W1 Android 7.0 Nougat NGN 16,000 ~ USD 45 Lenovo Ideapad Windows 10 NGN 90,000 ~ USD 250

16 % of Global Population with Access to Internet 60% 51.7% 45% 30% 15% 0% 0.4%

17 Assistive Technologies

18 Next Billion Users

19 Performance Internationalisation Building for the NBU Accessibility

20 Performance

21 In Nigeria, the average person has to work 28 hours to earn enough to use 500 MB of data. In Germany, it s only 1 hour 2014 report by McKinsey & Company

22 Internationalisation

23 Accessibility

24 CSS for the Next Billion Users

25 4 things Is CSS the right tool? Selecting HTML CSS Declarations CSS Delivery

26 1 Is CSS the right tool?

27 If you only have a hammer, you tend to see every problem as a nail A Wise Carpenter

28 CSS-Only Functionality

29 Use the Right Tool Content Presentation Functionality

30 When to use HTML input[type= password ]:: after { content: Enter your password }

31 When to use HTML <label for= password >Enter your password</ label> <input type= password id= password >

32 When to use JavaScript

33 When to use JavaScript

34 2 Selecting HTML

35 .element { color: #bae; }

36 Use globally-aware naming conventions

39 Naming Conventions.text-left { text-align: left; }

40 Naming Conventions [dir= ltr ].text-start { text-align: left; } [dir= rtl ].text-start { } text-align: right;

41 margin-block-start: 10px ; flex-direction: row rowreverse column column-reverse ; flex-wrap: nowrap wrap wrap-reverse ; justify-content: flex-start flex-end center space-between space-around spaceevenly ; align-items: flex-start flex-end center baseline stretch; align-content: flex-start flexend center space-between space-around stretch ; display: grid inline-grid ; text-align: start ; aligncontent: center start end space-between spacearound space-evenly ; justify-items: center start end stretch ; align-items: center start end stretch ; justify-self: center start end stretch ; align-self: center start end stretch ;

42 Beware of expensive selectors

43 <ul> <li><a href= >One</a></li> <li><a href= >Two</a></li> <li><a id= boc href= >Three</a></li> </ul>

44 a[href= ] a:not[href*= cssday.nl ] ul li:nth-child(3) a ul li:last-child a #boc

45 Selector Efficiency 1. ID, e.g. #foo 2. Class, e.g..foo Fastest 3. Tag, e.g. div 4. Adjacent Sibling, e.g. header + main 5. Child Combinator, e.g. ul > li 6. Descendant, e.g ul li 7. Universal, e.g. * Slowest 8. Attribute, e.g. a[href= ] 9. Pseudo-classes & pseudo-elements, e.g. a:visited

46 #boc Fastest ul li:nth-child(3) a ul li:last-child a a[href= ] Slowest a:not[href*= cssday.nl ]

47 Use Performant Naming Conventions <div class= button icon primary > <div class= button primary > button:not(.icon).primary { }

48 Use Performant Naming Conventions <div class= button button--icon button--primary > <div class= button button--primary >.button { }.button--primary { }

49 3 CSS Declarations

50 .element { color: #bae; }

51 Can I Use [insert-awesome-thing]?

52 Do I need to use [insert-awesome-thing]?

54 Float-Based Layout.row {.column { } margin: 0px (-$small-space); position: relative; width: 100%; min-height: 1px; padding: 0px $small-space;.row:after { display: block; clear: both; content: ""; } }.column, [dir="rtl"].reverse.column { float: left; }

55 Float-Based Layout It just works.row {.column { } margin: 0px (-$small-space); position: relative; width: 100%; min-height: 1px; padding: 0px $small-space;.row:after { display: block; clear: both; content: ""; } }.column, [dir="rtl"].reverse.column { float: left; }

56 Do I need to use [insert-awesome-thing]? Actually, yes.

58 Grid-Based Layout.group.cards { display: grid; grid-template-columns: repeat(1, (min-width: $card-min-width) { grid-template-columns: repeat(auto-fit, minmax($card-min-width, 1fr)); } }

60 Use feature queries!

61 .group.cards { /* Fallback styles here */ (display: grid) {.group.cards { /* grid-based layout */ } }

62 Choosing performant CSS properties

63 The Critical Rendering Path

64 Changes to CSS can re-trigger stages of the critical rendering path

65 Animating the top property

66 Animating the transform property

68 Respect end-user preferences

69 Reduced-motion.animated { animation-name: 3s infinite alternate slidein; (prefers-reduced-motion: reduce) { }.animated { animation: none; }

70 !important body { font-size: 8px!important; }

71 Our!important declarations will override everything except userdefined!important declarations

72 Progressive Enhancement div { background-color: rgb(0,0,0); background-color: rgba(0,0,0,0.5); }

73 4 CSS Delivery

75 CSS is a render-blocking resource

76 Solutions Modularising CSS Preloading CSS

77 1. Loading CSS based on Modularising CSS media types 2. Inlining Critical CSS 3. Styles in the <body>

78 <link rel= stylesheet media= (max-width: 600px) src= mobile.css > 1. Loading CSS based on media types 2. Inlining Critical CSS <link rel= stylesheet 3. Styles in the <body> media= (min-width: 600px) src= desktop.css >

79 <head> <style id= critical > #hero { } </style> <script> loadcss( full.css ); </script> </head> 1. Loading CSS based on media types 2. Inlining Critical CSS 3. Styles in the <body>

80 <body> <style>header { /* */ }</style> <header> </header> <style>main { /* */ }</style> <main> </main> 1. Loading CSS based on media types 2. Inlining Critical CSS <style>footer { /* */ }</style> <footer> </footer> </body> 3. Styles in the <body>

Inlining Critical CSS <style>footer { /* */ }</style> <footer> </footer> </body> 3.

81 <body> <style>header { /* */ }</style> <header> </header> <style>main { /* */ }</style> <main> </main> 1. Loading CSS based on media types 2. Inlining Critical CSS <style>footer { /* */ }</style> <footer> </footer> </body> 3. Styles in the <body> The use of <style> in the <body> of the document may cause restyling, trigger layout and/or cause repainting, and hence, should be used with care. HTML Specification

82 1. Preload Link 2. HTTP/2 Push Preloading CSS

83 1. Preload Link 2. HTTP/2 Push <link rel= preload as style href= stylesheet.css >

84 1. Preload Link 2. HTTP/2 Push <FilesMatch "\.html$"> Header set Link </css/styles.css>; rel=preload; as=style" <FilesMatch>

85 Let s Review Is CSS the right tool? Selecting HTML CSS Declarations CSS Delivery

86 Next Billion Users

87 Your Billion Users

88 ireaderinokun.com Thank you!

CSS Selectors. element selectors. .class selectors. #id selectors

CSS Selectors. element selectors. .class selectors. #id selectors CSS Selectors Patterns used to select elements to style. CSS selectors refer either to a class, an id, an HTML element, or some combination thereof, followed by a list of styling declarations. Selectors