CSS Guidelines

Partially Inspired by http://codeguide.co/

Golden rule

Every line of code should appear to be written by a single person, no matter the number of contributors.


Questions on the terms used here? See the syntax section of the Cascading Style Sheets article on Wikipedia.

Declaration Order

Sort your declarations alphabetically to make it easy to read and avoid duplicate entries. Use F9 in Sublime Text to sort selected text alphabetically.

Don't Use @import

Compared to <link>s, @import is slower, adds extra page requests, and can cause other unforeseen problems. Avoid them and instead opt for an alternate approach:

For more information, read this article by Steve Souders.

Media query placement

Place media queries as close to their relevant rule sets whenever possible. Don't bundle them all in a separate stylesheet or at the end of the document. Doing so only makes it easier for folks to miss them in the future.

.element { ... }
.element-avatar { ... }
.element-selected { ... }

@media (min-width: 480px) {
	.element { ...}
	.element-avatar { ... }
	.element-selected { ... }

Single declarations

In instances where a rule set includes only one declaration, consider removing line breaks for readability and faster editing. Any rule set with multiple declarations should be split to separate lines.

The key factor here is error detection-e.g., a CSS validator stating you have a syntax error on Line 183. With a single declaration, there's no missing it. With multiple declarations, separate lines is a must for your sanity.

/* Single declarations on one line */
.span1 { width: 60px; }
.span2 { width: 140px; }
.span3 { width: 220px; }

/* Multiple declarations, one per line */
.sprite {
	display: inline-block;
	width: 16px;
	height: 15px;
	background-image: url(../img/sprite.png);
.icon           { background-position: 0 0; }
.icon-home      { background-position: 0 -20px; }
.icon-account   { background-position: 0 -40px; }

Nesting with LESS

Nesting makes CSS cleaner and easier to read, and lessens the need to write duplicate selectors. It also allows collapsing sections in your code editor to hide what you don't need to see.

Keep in mind nesting will increase your specificity, overriding less specific CSS.

#sidebar {
	background: white;
	width: 220px;
	#section {
		color: red;
		width: 100px;
	table {
		background: orange;
		width: 100%;


Code is written and maintained by people. Ensure your code is descriptive, well commented, and approachable by others. Great code comments convey context or purpose. Do not simply reiterate a component or class name.

Be sure to write in complete sentences for larger comments and succinct phrases for general notes. For elaborate features and components we can document in this coding guide.

You can use double forward slash (//) to write comments in LESS.

Class names

It's also useful to apply many of these same rules when creating Sass and Less variable names.

/* Bad example */
.t { ... }
.red { ... }
.header { ... }

/* Good example */
.tweet { ... }
.important { ... }
.tweet-header { ... }


Additional reading:

/* Bad example */
span { ... }
.page-container #stream .stream-item .tweet .tweet-header .username { ... }
.avatar { ... }

/* Good example */
.avatar { ... }
.tweet-header .username { ... }
.tweet .avatar { ... }
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