--- /dev/null
+# value-list-comma-space-before
+
+Require a single space or disallow whitespace before the commas of value lists.
+
+```css
+a { background-size: 0 ,0; }
+/** ↑
+ * The space before these commas */
+```
+
+## Options
+
+`string`: `"always"|"never"|"always-single-line"|"never-single-line"`
+
+### `"always"`
+
+There *must always* be a single space before the commas.
+
+The following patterns are considered violations:
+
+```css
+a { background-size: 0,0; }
+```
+
+```css
+a { background-size: 0
+ , 0; }
+```
+
+The following patterns are *not* considered violations:
+
+```css
+a { background-size: 0 ,0; }
+```
+
+```css
+a { background-size: 0 ,
+ 0; }
+```
+
+### `"never"`
+
+There *must never* be whitespace before the commas.
+
+The following patterns are considered violations:
+
+```css
+a { background-size: 0 ,0; }
+```
+
+```css
+a { background-size: 0 ,
+ 0; }
+```
+
+The following patterns are *not* considered violations:
+
+```css
+a { background-size: 0,0; }
+```
+
+```css
+a { background-size: 0,
+ 0; }
+```
+
+### `"always-single-line"`
+
+There *must always* be a single space before the commas in single-line value lists.
+
+The following patterns are considered violations:
+
+```css
+a { background-size: 0,0; }
+```
+
+The following patterns are *not* considered violations:
+
+```css
+a { background-size: 0 ,0; }
+```
+
+```css
+a { background-size: 0 ,
+ 0; }
+```
+
+```css
+a { background-size: 0
+ , 0; }
+```
+
+### `"never-single-line"`
+
+There *must never* be whitespace before the commas in single-line value lists.
+
+The following patterns are considered violations:
+
+```css
+a { background-size: 0 ,0; }
+```
+
+The following patterns are *not* considered violations:
+
+```css
+a { background-size: 0,0; }
+```
+
+```css
+a { background-size: 0,
+ 0; }
+```
+
+```css
+a { background-size: 0 ,
+ 0; }
+```