HTML & CSS naming convention – a modern approach

 

Excerpts original from Stackoverflow

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First, if you are not aware of this common (good?) practice: avoid IDs as styling hooks, try to only use Classes

Because:

• only very few blocks (ie. page-header, page-footer) can 100% garantee the fact that they will not be reused elsewhere

• you want to keep specificity low, there will always be times you need to override it (without using an extra ID selector or !important)

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Common requirements/conventions:

• Names should be intuitive/meaningfull
• Do NOT abbreviate names unless its a really well known abbreviation (ie. msg for Message, accnt for account)
• Use known/common names: .site-nav, .aside-nav, .global-head, .btn-primary, .btn-secondary
• Allow structural hierarchy (ie. BEM convention)
• Use - or _ in namings: probably subjective (devs' opinions) & depending on the keyboard languages used. Note that camelCase has been left aside for browser-compatibility issues I believe, although I never found a proof for this.
• Never use elements in selectors unless exceptional case: this allows for more flexibility, ie. you have buttons you created using <input type="button"></input> and you want to switch to using <button></button>, if you used element types in some selectors then you can plan some annoying/time-consuming refactoring/testing/prod-bug-fixing, whereas if you use element-less selectors then the switch will be infinitely easier. SMACCS also has it in its conventions
• For states, try to match known conventions from other languages (php, java, c#): ie, use "is-active", "is-badass", & so on
• Name from left-to-right: from the most generic to the most precise, ie. btn-bluetheme-create-accnt or accordion-modrnlook-userlist
• a class or id name should always be specific enough to be searched across a whole project & return only the relevant results
• Prefer direct descendant if you use descendent selectors - use .module-name > .sub-module-name vs .module-name .sub-module-name - you'll save yourself some headache in the future (simpler CSS but also more performant, although the term "CSS performance might be laughable")

As discussed below you may want to consider using Structural naming convention OR/AND Presentational naming convention (or skins). I'd prefer the structural one overall but then there always are cases where it's needed (ie. using different button styles on 1 website is not unusual & it might be handy/tempting to name them such as btn-dark & btn-light).

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Known conventions:

Structural naming convention: name element's class by describing what it is, rather than where it is or how it looks. See examples below.

.page-container
     .page-wrap-header-n-content
     .page-header
          .branding-logo
          .branding-tagline
          .wrapper-search
          .page-nav-main
     .page-main-content
     .page-secondary-content
          .nav-supplementary
     .page-footer
          .site-info

Presentational naming convention: name element's class by describing its location and/or appearance. See examples below.

.theme-ocean-blue
.skin-red-tango

BEM naming convention: stands for "Block, Element, Modifier". Syntax is such as <module-name>__<sub-module-name>--<modifier-or-state>. Block is a the "main" container, a kind of module/component whatever you call it. Element is just a child component of the main component (the Block). Modifier is some kind of state. Peculiarities: the syntax (usage of dbl underscore & dbl dash), & child elements must contain their closest component's name. See examples below.

.nav-primary
.nav-primary__list
.nav-primary__item
.nav-primary__link
.nav-primary__link--is-active

.grid
.grid__item
.grid__description
.grid__img-wrap
.grid__img

.global-footer
.global-footer__col
.global-footer__header
.global-footer__link

OCSS naming convention: stands for Object Oriented CSS. Uses skins for branding purposes or consistency of design (ie. bg color, border color, ...). Abstracts the structural styles. Example of abstract structural style below.

 .global-width {
      min-width: 780px;    /* minimum width */
      max-width: 1400px;   /* maximum width */
      margin: 0 auto;      /* Centering using margin: auto */
      position: relative;  /* Relative positioning to create a positioning context for child elements */
      padding-left: 20px;
      padding-right: 20px;
      overflow: hidden;    /* Overflow set to "hidden" for clearfixing */
 }

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Some CSS guidelines:

There has been a "trend" to share your CSS styleguide, here are a few you can read to pick & choose whatever seems to fit for your need (naming convention but also much more, this may be out of scope of your question):

• github.com/styleguide/css/
  
• cssguidelin.es
  
• css-tricks.com/sass-style-guide
  
• codepen.io/chriscoyier/blog/codepens-css

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Resources:

• http://csswizardry.com/2013/01/mindbemding-getting-your-head-round-bem-syntax/
  
• http://www.smashingmagazine.com/2011/12/12/an-introduction-to-object-oriented-css-oocss/
  
• http://bem.info/method/definitions/
  
• http://csswizardry.com/2013/01/mindbemding-getting-your-head-round-bem-syntax/
  
• http://www.smashingmagazine.com/2011/12/12/an-introduction-to-object-oriented-css-oocss/
  
• http://www.stuffandnonsense.co.uk/archives/naming_conventions_table.html
  
• http://sixrevisions.com/css/css-tips/css-tip-2-structural-naming-convention-in-css/
  
• CSS class naming convention
  
• Can I use camel-case in CSS class names
  
• https://developer.mozilla.org/en-US/docs/Web/Guide/CSS/Underscores_in_class_and_ID_Names
  
• http://programmers.stackexchange.com/questions/141988/practical-considerations-for-html-css-naming-conventions-syntax
  
• http://smacss.com/book/type-module
  
• github.com/styleguide/css/
  
• cssguidelin.es