Css best practices style guide and tips

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

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

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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Slide Decks & Source Code
• Slide Deck – http://slidesha.re/19NZInK
• Source Code – http://GitHub.com/docluv
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CSS
• Language Defining Rendering Rules
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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

CSS
•Rules
• Defined using selector syntax
•Properties
• The specifics
•Media Queries
• Define Rules Based on Browser & Device Characteristics
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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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CSS Selector Syntax
• Element
• H1, DIV, P
• Class
• .btn, . spa-child-view
• ID
• #tryToAvoid
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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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By Attribute/type
input[type="email"] {
color:blue;
}
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Starts With
[class^="my-class-"] {
color:red;
}
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Ends With
[class$=“-my-class"] {
color:red;
}
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Contains
[class*="class"] {
color:red;
}
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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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Remove webkit Input Border
input[type="text"]:focus { outline: none; }
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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)

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

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/

<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>

@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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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"; }

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

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

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

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

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

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

• <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>

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

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

Responsive Web Design
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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

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

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

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

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

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

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

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

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

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

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

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

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

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
}
}
},
});

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

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

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.

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`.

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.

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));
}

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

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;
}

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%;

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

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

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

• 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

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

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

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%);
}

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

Css best practices style guide and tips

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