This document discusses CSS best practices and tips. It covers topics such as CSS selectors, properties, units, responsive design, animations, and creating shapes with CSS. Code examples are provided to demonstrate CSS techniques like creating fluid layouts, using media queries, properly formatting CSS rules, and perfectly centering elements.

1. CSS Best Practices, Style
Guide, and Tips
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Chris Love
http://love2dev.com
@ChrisLove

2. Who Am I?
• ASP.NET MVP
• ASP Insider
• MS Edge User Agent
• Author
• Speaker
• Tweaker, Lover of Web, JavaScript, CSS & HTML5
• @ChrisLove
• Love2Dev.com
#ITDEVCON

3. High Performance Single Page Web Applications
• Responsive Design
• Touch
• Mobile First
• SPA
• Extensible, Scalable Architecture
• Web Build and Workflow
• Goes Really Fast!
• ~395 Pages
• 20 Chapters
• $9.99
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4. Slide Decks & Source Code
• Slide Deck – http://slidesha.re/19NZInK
• Source Code – http://GitHub.com/docluv
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5. CSS
• Language Defining Rendering Rules
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6. CSS
.main-content {
overflow: hidden;
left: 6.3166666%;
right: 0;
top: 50px;
bottom: 4.166666%;
position: absolute;
border-radius: 5px 5px 0 0;
background-color: #000000;
-moz-transition: all 700ms ease-out;
-o-transition: all 700ms ease-out;
-webkit-transition: all 700ms ease-out;
transition: all 700ms ease-out;
}
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Selector/Rule
Properties
Vendor Specific

7. CSS
•Rules
• Defined using selector syntax
•Properties
• The specifics
•Media Queries
• Define Rules Based on Browser & Device Characteristics
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8. CSS Property Units
•px – pixels
•% - percent
•em – relative to the element’s font-size
•rem – Relative to the root element’s font-size
•vh/vw – Viewport Height/Viewport Width
•Any 0 does not require a unit
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9. CSS Selector Syntax
• Element
• H1, DIV, P
• Class
• .btn, . spa-child-view
• ID
• #tryToAvoid
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10. Advanced CSS Selector Syntax
• Nested Selectors
• Allows You To Apply Rules to Children of Matched Elements
• .main-content p
• Be careful to avoid complexity
• Dynamic By Attributes
• script[class='spa-view']
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11. By Attribute/type
input[type="email"] {
color:blue;
}
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12. Starts With
[class^="my-class-"] {
color:red;
}
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13. Ends With
[class$=“-my-class"] {
color:red;
}
#ITDEVCON

14. Contains
[class*="class"] {
color:red;
}
#ITDEVCON

15. Customize Social Links
a[href*="twitter.com"] { color:#55acee; }
a[href*="facebook.com"] { color:#3b5998; }
a[href*="google.com"] { color:#db4437; }
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16. Remove webkit Input Border
input[type="text"]:focus { outline: none; }
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17. psuedo-classes
• Define CSS Rules for Element States
• Hover
• Active
• Define Rules for hidden elements
• :before, :after
• Define Rules for nth Element
• :nth-of-type(3n)

18. Content Property
• Defines ‘text’ value for matched element
• Useful with :before and :after pseudo element

19. Responsive Table Trick
• Tables Create a Unique Responsive Design Problem
• Change CSS To Change Rendering Rules
• Turn Table into a fake set of DIVs
• Leverage content property to define value labels
• https://css-tricks.com/responsive-data-tables/

20. #ITDEVCON

21. Responsive Table Trick
<table>
<thead>
<tr>
<th>First Name</th>
<th>Last Name</th>
<th>Job Title</th>
</tr>
</thead>
<tbody>
<tr>
<td>James</td>
<td>Matman</td>
<td>Chief Sandwich Eater</td>
</tr>
<tr>
<td>The</td>
<td>Tick</td>
<td>Crimefighter Sorta</td>
</tr>
</tbody>
</table>

22. Responsive Table Trick
@media only screen and (max-width: 760px),
(min-device-width: 768px) and (max-device-width: 1024px) {
table, thead, tbody, th, td, tr {
display: block;
}
}
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23. Responsive Table Trick
td:nth-of-type(1):before { content: "First Name"; }
td:nth-of-type(2):before { content: "Last Name"; }
td:nth-of-type(3):before { content: "Job Title"; }
td:nth-of-type(4):before { content: "Favorite Color"; }
td:nth-of-type(5):before { content: "Wars of Trek?"; }
td:nth-of-type(6):before { content: "Porn Name"; }
td:nth-of-type(7):before { content: "Date of Birth"; }
td:nth-of-type(8):before { content: "Dream Vacation City"; }
td:nth-of-type(9):before { content: "GPA"; }
td:nth-of-type(10):before { content: "Arbitrary Data"; }

24. CSS Selector Specificity
• Complex Specificity
• .main-content > article #myArticleId p
• Leads to large CSS files
• Makes Code Unmanageable
• Lower the Score the Better
• Browsers Parse Selectors Right to Left
• * Avoid Universal Selector

25. Right-Left Rule
• .main-content > article #myArticleId p
• Translates to:
• #myArticleId p
• Think More Like the Browser When Defining Selectors

26. Calculate CSS Specificity
• Count the Inline Style
• count the number of ID selectors in the selector (= a)
• count the number of class selectors, attributes selectors, and pseudo-
classes in the selector (= b)
• count the number of type selectors and pseudo-elements in the
selector (= c)
• ignore the universal selector

27. Calculate CSS Specificity
http://specificity.keegan.st/

28. BEM Naming Convention
• Block
• Element
• Modifier
• Bootstrap and Primer Good Examples

29. BEM Naming Convention
• .btn {…}
• .btn-primary {…}
• .btn-primary:disabled {…}
• .btn-xs {…}
• Might also see __ between words

30. BEM Naming Convention
• <button type="button" class="btn btn-primary">Primary</button>
• <button type="button" class="btn btn-success">Success</button>
• <button type="button" class="btn btn-info">Info</button>
• <button type="button" class="btn btn-warning">Warning</button>

31. CSS Cascading
• Last, Most Specific Rule Wins
• Be mindful of your CSS Definition Order
• Overwrites Previously Defined Rules
• Simple rule make this easy to maintain and create

32. Responsive Design
“this unspoken agreement to pretend that we had a certain size. And that size
changed over the years. For a while, we all sort of tacitly agreed that 640 by 480
was the right size, and then later than changed to 800:600, and 1024; we seem
to have settled on this 960 pixel as being this like, default. It’s still unknown. We
still don’t know the size of the browser; it’s just like this consensual
hallucination that we’ve all agreed to participate in: “Let’s assume the browser
has a browser width of at least 960 pixels.”
Jeremy Keith
bit.ly/1bhH6rw

33. Responsive Web Design
#ITDEVCON

34. Responsive Web Design
• Introduced by Ethan Marcotte 2010 -
bit.ly/178an9e
• Web Design Approach To Create An Optimal
Viewing Experience Across All Browser ViewPorts
• Fluid Layouts
• Media Queries
• Minimal if any JavaScript Required

35. Fluid Layout
• Stretch as the Browser ViewPort Changes
• Browser’s Viewable Area Inside the Chrome
• Serve as the Foundation for the Web Application
Layout
• Great Way To Create Native Like Experience

36. Fluid Layout
• Leverage Absolute Positioning
• Enables Fixed Positioning Without position:fixed
• Leverage overflow scrolling

37. Media Queries
@media (min-width: 600px) {
/* Selectors & Rules */
}
@media (min-width: 820px) {
/* Selectors & Rules */
}
@media (min-width: 1080px) {
/* Selectors & Rules */
}

38. Avoid Embedded Styles
• Don't separate content from design
• Cause more maintenance headaches
• Make your pages larger
• Do not take advantage of Http Caching
• Lead to Duplicate Rules

39. CSS - Files
• Should
• Use External Files
• Hosted on a CDN
• Bundled & Minified *
• HTTP/2 Changes the Bundling Rule

40. CSS – Debug Files
• Should
• Use Many Files
• They Should Correlate to a Purpose
• View
• Component
• Layout

41. CSS –Files
css/
site.min.css
/dev
/libs
/ui
/views

42. CSS Best Practices
• Link to External Files in the HEAD
• Ensures CSS read before HTML
• Avoid Using @import
• Causes CSS to be Parsed After Document

43. CSS Reset
• Establishes a Common Base
• Each Browser has a default CSS stylesheet
• Many Resets Availble
• Normalize.css probably most popular
• Popular libraries have resets; ex bootstrap uses normalize

44. CSS Libraries
• Many Available
• Bootstrap is the current defacto standard
• Primer based on Boostrap
• Created by bootstrap author
• GitHub’s internal library
• https://github.com/primer/primer

45. CSS Libraries
• Be Careful to not be Completely Dependent on Library
• Understand How CSS Rules, Apply Best Practices
• Build Your Own Custom Version
• Grunt/Gulp

46. Critical CSS
• The CSS Required to Render The Above the Fold Content
• Embed Inline, in HEAD element
• Instant Render if HTML < 14kb
• Works great for a SPA
• criticalCSS Node Module
• https://www.npmjs.com/package/criticalcss

47. Critical CSS Grunt
grunt.initConfig({
criticalcss: {
custom: {
options: {
url: "http://localhost:4000",
width: 1200,
height: 900,
outputfile: "dist/critical.css",
filename: "/path/to/local/all.css", // Using path.resolve( path.join( ... ) ) is a good idea here
buffer: 800*1024,
ignoreConsole: false
}
}
},
});

48. UnCSS Grunt
uncss: {
dist: {
src: ['app/index.html'],
dest: 'app/css/tidy.css',
options: {
report: 'min'
}
}
}
https://www.npmjs.com/package/grunt-uncss

49. CSS Code Style
• Define Section Titles
/*------------------------------------*
$MAIN
*------------------------------------*/

50. CSS Rule Formatting
• Use one discrete selector per line in multi-selector rulesets.
• Include a single space before the opening brace of a
ruleset.
• Include one declaration per line in a declaration block.
• Use one level of indentation for each declaration.
• Include a single space after the colon of a declaration.

51. CSS Rule Formatting
• Use lowercase and shorthand hex values, e.g., `#aaa`.
• Use single or double quotes consistently. Preference is for
double quotes, e.g., `content: ""`.
• Quote attribute values in selectors, e.g.,
`input[type="checkbox"]`.
• _Where allowed_, avoid specifying units for zero-values,
e.g., `margin: 0`.

52. CSS Rule Formatting
• Include a space after each comma in comma-separated
property or function values.
• Include a semi-colon at the end of the last declaration in a
declaration block.
• Place the closing brace of a ruleset in the same column as
the first character of the ruleset.
• Separate each ruleset by a blank line.

53. Rule Formatting Example
.selector-1,
.selector-2,
.selector-3[type="text"] {
-webkit-box-sizing: border-box;
-moz-box-sizing: border-box;
box-sizing: border-box;
display: block;
font-family: helvetica, arial, sans-serif;
color: #333;
background: #fff;
background: linear-gradient(#fff, rgba(0, 0, 0, 0.8));
}

54. Consistently Declare Property Order
• Makes it Easier to Read
• Makes it Easier for Teams to Share Code

55. Consistently Declare Property Order
.selector {
/* Positioning */
position: absolute;
z-index: 10;
top: 0;
right: 0;
bottom: 0;
left: 0;
/* Display & Box Model */
display: inline-block;
overflow: hidden;
box-sizing: border-box;
width: 100px;
height: 100px;
padding: 10px;
border: 10px solid #333;
margin: 10px;
/* Other */
background: #000;
color: #fff;
font-family: sans-serif;
font-size: 16px;
text-align: right;
}

56. Clock-Wise Rule
• Margin & Padding Work Clock-wise around the element
• margin: 5% 10% 15% 20%;
• margin-top : 5%;
• margin-right : 10%;
• margin-bottom : 15%;
• margin-left : 20%;

57. Element Layout Box

58. CSS Animations
• Do Not Use JavaScript Libraries for Animations
• CSS Animations are Native
• Run on the GPU

59. CSS Key-Frame Animations
• Allow You To Define Complex Animations
• Define Rules/Properties Along a Timeline
• Animate.css is a collection of turn-key animations
• http://daneden.me/animate

60. CSS Key-Frame Animations
• Can be Applied by adding and removing CSS classes on
an element
loginDlg.classList.add("fadeInDown");
showLogin.classList.add("fadeOut");
loginDlg.classList.remove("fadeOutUp");

61. CSS Key-Frame Animations
• Can be Applied by adding and removing CSS classes on
an element
loginDlg.classList.add("fadeInDown");
showLogin.classList.add("fadeOut");
loginDlg.classList.remove("fadeOutUp");
• http://bit.ly/1Lt1kTb

62. CSS Shapes
• CSS Can be Used to Create All Sorts of Shapes
• http://www.cssshapes.com/

63. Create a CSS Heart
• My Site’s Logo is a CSS Heart
• Here is how to create it:
• http://bit.ly/1NF3Sjf

64. Perfectly Align to Center
.my-class-parent {
position:relative;
}
.my-class {
position:absolute;
top:50%;
left:50%;
-webkit-transform:translate(-50%, -50%);
transform:translate(-50%, -50%);
}

65. High Performance Single Page Web
Applications
• Responsive Design
• Touch
• Mobile First
• SPA
• Extensible, Scalable Architecture
• Web Build and Workflow
• Goes Really Fast!
• ~395 Pages
• 20 Chapters
• $9.99