├── .scss-lint.yml
└── README.md
/.scss-lint.yml:
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1 | linters:
2 |
3 | BorderZero:
4 | enabled: true
5 | convention: none
6 |
7 | BemDepth:
8 | enabled: true
9 |
10 | DeclarationOrder:
11 | enabled: false
12 |
13 | LeadingZero:
14 | enabled: false
15 |
16 | PropertySortOrder:
17 | enabled: false
18 |
19 | QualifyingElement:
20 | enabled: false
21 |
22 | SelectorFormat:
23 | enabled: true
24 | convention: hyphenated_BEM
25 | class_convention: ^(?!js-).*
26 | class_convention_explanation: should not be written in the form js-*
27 |
28 | SingleLinePerProperty:
29 | enabled: true
30 | allow_single_line_rule_sets: false
31 |
32 | StringQuotes:
33 | enabled: true
34 | style: double_quotes
35 |
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/README.md:
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1 | # Airbnb CSS / Sass Styleguide
2 |
3 | *A mostly reasonable approach to CSS and Sass*
4 |
5 | ## Table of Contents
6 |
7 | 1. [Terminology](#terminology)
8 | - [Rule Declaration](#rule-declaration)
9 | - [Selectors](#selectors)
10 | - [Properties](#properties)
11 | 1. [CSS](#css)
12 | - [Formatting](#formatting)
13 | - [Comments](#comments)
14 | - [OOCSS and BEM](#oocss-and-bem)
15 | - [ID Selectors](#id-selectors)
16 | - [JavaScript hooks](#javascript-hooks)
17 | 1. [Sass](#sass)
18 | - [Syntax](#syntax)
19 | - [Ordering](#ordering-of-property-declarations)
20 | - [Mixins](#mixins)
21 | - [Placeholders](#placeholders)
22 | - [Nested selectors](#nested-selectors)
23 |
24 | ## Terminology
25 |
26 | ### Rule declaration
27 |
28 | A “rule declaration” is the name given to a selector (or a group of selectors) with an accompanying group of properties. Here's an example:
29 |
30 | ```css
31 | .listing {
32 | font-size: 18px;
33 | line-height: 1.2;
34 | }
35 | ```
36 |
37 | ### Selectors
38 |
39 | In a rule declaration, “selectors” are the bits that determine which elements in the DOM tree will be styled by the defined properties. Selectors can match HTML elements, as well as an element's class, ID, or any of its attributes. Here are some examples of selectors:
40 |
41 | ```css
42 | .my-element-class {
43 | /* ... */
44 | }
45 |
46 | [aria-hidden] {
47 | /* ... */
48 | }
49 | ```
50 |
51 | ### Properties
52 |
53 | Finally, properties are what give the selected elements of a rule declaration their style. Properties are key-value pairs, and a rule declaration can contain one or more property declarations. Property declarations look like this:
54 |
55 | ```css
56 | /* some selector */ {
57 | background: #f1f1f1;
58 | color: #333;
59 | }
60 | ```
61 |
62 | ## CSS
63 |
64 | ### Formatting
65 |
66 | * Use soft tabs (2 spaces) for indentation
67 | * Prefer dashes over camelCasing in class names. Underscores are OK if you're using BEM (see [OOCSS and BEM](#oocss-and-bem) below).
68 | * Do not use ID selectors
69 | * When using multiple selectors in a rule declaration, give each selector its own line.
70 | * Put a space before the opening brace `{` in rule declarations
71 | * In properties, put a space after, but not before, the `:` character.
72 | * Put closing braces `}` of rule declarations on a new line
73 | * Put blank lines between rule declarations
74 |
75 | **Bad**
76 |
77 | ```css
78 | .avatar{
79 | border-radius:50%;
80 | border:2px solid white; }
81 | .no, .nope, .not_good {
82 | // ...
83 | }
84 | #lol-no {
85 | // ...
86 | }
87 | ```
88 |
89 | **Good**
90 |
91 | ```css
92 | .avatar {
93 | border-radius: 50%;
94 | border: 2px solid white;
95 | }
96 |
97 | .one,
98 | .selector,
99 | .per-line {
100 | // ...
101 | }
102 | ```
103 |
104 | ### Comments
105 |
106 | * Prefer line comments (`//` in Sass-land) to block comments.
107 | * Prefer comments on their own line. Avoid end-of-line comments.
108 | * Write detailed comments for code that isn't self-documenting:
109 | - Uses of z-index
110 | - Compatibility or browser-specific hacks
111 |
112 | ### OOCSS and BEM
113 |
114 | We encourage some combination of OOCSS and BEM for these reasons:
115 |
116 | * It helps create clear, strict relationships between CSS and HTML
117 | * It helps us create reusable, composable components
118 | * It allows for less nesting and lower specificity
119 | * It helps in building scalable stylesheets
120 |
121 | **OOCSS**, or “Object Oriented CSS”, is an approach for writing CSS that encourages you to think about your stylesheets as a collection of “objects”: reusuable, repeatable snippets that can be used independently throughout a website.
122 |
123 | * Nicole Sullivan's [OOCSS wiki](https://github.com/stubbornella/oocss/wiki)
124 | * Smashing Magazine's [Introduction to OOCSS](http://www.smashingmagazine.com/2011/12/12/an-introduction-to-object-oriented-css-oocss/)
125 |
126 | **BEM**, or “Block-Element-Modifier”, is a _naming convention_ for classes in HTML and CSS. It was originally developed by Yandex with large codebases and scalability in mind, and can serve as a solid set of guidelines for implementing OOCSS.
127 |
128 | * CSS Trick's [BEM 101](https://css-tricks.com/bem-101/)
129 | * Harry Roberts' [introduction to BEM](http://csswizardry.com/2013/01/mindbemding-getting-your-head-round-bem-syntax/)
130 |
131 | **Example**
132 |
133 | ```html
134 |
135 |
136 |
Adorable 2BR in the sunny Mission
137 |
138 |
139 |
Vestibulum id ligula porta felis euismod semper.
140 |
141 |
142 |
143 | ```
144 |
145 | ```css
146 | .listing-card { }
147 | .listing-card--featured { }
148 | .listing-card__title { }
149 | .listing-card__content { }
150 | ```
151 |
152 | * `.listing-card` is the “block” and represents the higher-level component
153 | * `.listing-card__title` is an “element” and represents a descendant of `.listing-card` that helps compose the block as a whole.
154 | * `.listing-card--featured` is a “modifier” and represents a different state or variation on the `.listing-card` block.
155 |
156 | ### ID selectors
157 |
158 | While it is possible to select elements by ID in CSS, it should generally be considered an anti-pattern. ID selectors introduce an unnecessarily high level of [specificity](https://developer.mozilla.org/en-US/docs/Web/CSS/Specificity) to your rule declarations, and they are not reusable.
159 |
160 | For more on this subject, read [CSS Wizardry's article](http://csswizardry.com/2014/07/hacks-for-dealing-with-specificity/) on dealing with specificity.
161 |
162 | ### JavaScript hooks
163 |
164 | Avoid binding to the same class in both your CSS and JavaScript. Conflating the two often leads to, at a minimum, time wasted during refactoring when a developer must cross-reference each class they are changing, and at its worst, developers being afraid to make changes for fear of breaking functionality.
165 |
166 | We recommend creating JavaScript-specific classes to bind to, prefixed with `.js-`:
167 |
168 | ```html
169 |
170 | ```
171 |
172 | ## Sass
173 |
174 | ### Syntax
175 |
176 | * Use the `.scss` syntax, never the original `.sass` syntax
177 | * Order your `@extend`, regular CSS and `@include` declarations logically (see below)
178 |
179 | ### Ordering of property declarations
180 |
181 | 1. `@extend` declarations
182 |
183 | Just as in other OOP languages, it's helpful to know right away that this “class” inherits from another.
184 |
185 | ```scss
186 | .btn-green {
187 | @extend %btn;
188 | // ...
189 | }
190 | ```
191 |
192 | 2. Property declarations
193 |
194 | Now list all standard property declarations, anything that isn't an `@extend`, `@include`, or a nested selector.
195 |
196 | ```scss
197 | .btn-green {
198 | @extend %btn;
199 | background: green;
200 | font-weight: bold;
201 | // ...
202 | }
203 | ```
204 |
205 | 3. `@include` declarations
206 |
207 | Grouping `@include`s at the end makes it easier to read the entire selector, and it also visually separates them from `@extend`s.
208 |
209 | ```scss
210 | .btn-green {
211 | @extend %btn;
212 | background: green;
213 | font-weight: bold;
214 | @include transition(background 0.5s ease);
215 | // ...
216 | }
217 | ```
218 |
219 | 4. Nested selectors
220 |
221 | Nested selectors, _if necessary_, go last, and nothing goes after them. Add whitespace between your rule declarations and nested selectors, as well as between adjacent nested selectors. Apply the same guidelines as above to your nested selectors.
222 |
223 | ```scss
224 | .btn {
225 | @extend %btn;
226 | background: green;
227 | font-weight: bold;
228 | @include transition(background 0.5s ease);
229 |
230 | .icon {
231 | margin-right: 10px;
232 | }
233 | }
234 | ```
235 |
236 | ### Mixins
237 |
238 | Mixins, defined via `@mixin` and called with `@include`, should be used sparingly and only when function arguments are necessary. A mixin without function arguments (i.e. `@mixin hide { display: none; }`) is better accomplished using a placeholder selector (see below) in order to prevent code duplication.
239 |
240 | ### Placeholders
241 |
242 | Placeholders in Sass, defined via `%selector` and used with `@extend`, are a way of defining rule declarations that aren't automatically output in your compiled stylesheet. Instead, other selectors “inherit” from the placeholder, and the relevant selectors are copied to the point in the stylesheet where the placeholder is defined. This is best illustrated with the example below.
243 |
244 | Placeholders are powerful but easy to abuse, especially when combined with nested selectors. **As a rule of thumb, avoid creating placeholders with nested rule declarations, or calling `@extend` inside nested selectors.** Placeholders are great for simple inheritance, but can easily result in the accidental creation of additional selectors without paying close attention to how and where they are used.
245 |
246 | **Sass**
247 |
248 | ```sass
249 | // Unless we call `@extend %icon` these properties won't be compiled!
250 | %icon {
251 | font-family: "Airglyphs";
252 | }
253 |
254 | .icon-error {
255 | @extend %icon;
256 | color: red;
257 | }
258 |
259 | .icon-success {
260 | @extend %icon;
261 | color: green;
262 | }
263 | ```
264 |
265 | **CSS**
266 |
267 | ```css
268 | .icon-error,
269 | .icon-success {
270 | font-family: "Airglyphs";
271 | }
272 |
273 | .icon-error {
274 | color: red;
275 | }
276 |
277 | .icon-success {
278 | color: green;
279 | }
280 | ```
281 |
282 | ### Nested selectors
283 |
284 | **Do not nest selectors more than three levels deep!**
285 |
286 | ```scss
287 | .page-container {
288 | .content {
289 | .profile {
290 | // STOP!
291 | }
292 | }
293 | }
294 | ```
295 |
296 | When selectors become this long, you're likely writing CSS that is:
297 |
298 | * Strongly coupled to the HTML (fragile) *—OR—*
299 | * Overly specific (powerful) *—OR—*
300 | * Not reusable
301 |
302 |
303 | Again: **never nest ID selectors!**
304 |
305 | If you must use an ID selector in the first place (and you should really try not to), they should never be nested. If you find yourself doing this, you need to revisit your markup, or figure out why such strong specificity is needed. If you are writing well formed HTML and CSS, you should **never** need to do this.
306 |
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