CSS Best Practices, Style Guide, and Tips

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Chris Lovehttp://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

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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/typeinput[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 Linksa[href*="twitter.com"] { color:#55acee; } a[href*="facebook.com"] { color:#3b5998; } a[href*="google.com"] { color:#db4437; }

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Remove webkit Input Borderinput[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/

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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>

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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Responsive Table Tricktd: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

BEM Naming Convention• .btn {…}• .btn-primary {…}• .btn-primary:disabled {…}• .btn-xs {…}

•Might also see __ between words

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>

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 Keithbit.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 */}

@media (min-width: 820px) { /* Selectors & Rules */ }

@media (min-width: 1080px) { /* 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 –Filescss/

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 Gruntgrunt.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%;

Element Layout Box

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

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");

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

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