My preferred settings for CSSComb.

csscomb.json

{
    "remove-empty-rulesets": true,
    "always-semicolon": true,
    "color-case": "upper",
    "block-indent": "    ",
    "color-shorthand": false,
    "element-case": "lower",
    "eof-newline": false,
    "leading-zero": true,
    "quotes": "double",
    "sort-order-fallback": "abc",
    "space-before-colon": "",
    "space-after-colon": " ",
    "space-before-combinator": " ",
    "space-after-combinator": " ",
    "space-between-declarations": "\n",
    "space-before-opening-brace": " ",
    "space-after-opening-brace": "\n",
    "space-after-selector-delimiter": " ",
    "space-before-selector-delimiter": "",
    "space-before-closing-brace": "\n",
    "strip-spaces": true,
    "tab-size": true,
    "vendor-prefix-align": true
}