Following #1962 this PR changes the behaviour of the CSS Printer so that every selector in a selector list will be printed in its own line. A new option enables the previous behaviour.

This new behaviour is the one followed by

• Bootstrap (see example, but not enforced);
• Foundation for Sites (see example, but not enforced);
• Pure CSS (see example, but not enforced because using CSS Lint ¹)
• Semantic UI (see example, but not enforced because using CSS Lint ²)
• Many other

( ^{1, 2}: CSS Lint doesn’t have formatting linting rules. )

Example

Given this input:

.a,.b,.c {
  color: red;
}

New output:

.a,
.b,
.c {
  color: red;
}

Previous behaviour (can be enabled with option):

.a, .b, .c {
  color: red;
}

New option

To revert back to the previous behaviour we created the cssSelectorListSameLine option, which defaults to false.

From the CLI can be used as --css-selector-list-same-line.

The name of the option comes from the Style lint rule: selector-list-comma-newline-after.