.stylelintrc.js

module.exports = {
  rules: {
    //general
    indentation: 2, //indentation - spaces-2
    "max-empty-lines": 1, // max. consecutive empty lines
    "max-nesting-depth": 2, // max depth of css nesting
    "no-eol-whitespace": true, // no end-of-line whitespace
    "number-leading-zero": "always", // Require a leading zero for fractional numbers less than 1. (eg: 0.4, 0.6 ..)
    "property-case": "lower", // properties must be lowercase (eg: "width", not "WIdth")

    // block
    "block-no-empty": true, //empty blocks not allowed
    "block-opening-brace-space-before": "always", // always requires a single space before opening brace
    "block-closing-brace-newline-after": "always", // always requires a newline after the closing brace

    //color
    "color-no-hex": [true, { severity: "warning" }], // no hex values, with a warning
    "color-hex-case": "lower", // hex colors must be in lowercase
    "color-no-invalid-hex": true, // Disallow invalid hex colors.
    "color-named": "never", // named colors not allowed (eg: black/white/red...)

    //units
    "unit-disallowed-list": ["rem", "px", "em"], // these units are not allowed
    "unit-no-unknown": true, // unknown units disallowed

    //functions
    "function-allowed-list": ["/theme.*/", "url"], // disallow all other css functions except ones in this list (eg: rgb, calc, url ...)

    //declarations
    "declaration-no-important": true, // `!important` not allowed
    "declaration-block-no-duplicate-properties": [
      true,
      {
        ignore: ["consecutive-duplicates-with-different-values"],
      },
    ], // no duplicate properties allowed, except the consecutive ones with different values
  },
  extends: "stylelint-config-idiomatic-order",
  defaultSeverity: "error",
};