--- /dev/null
+# function-parentheses-space-inside
+
+Require a single space or disallow whitespace on the inside of the parentheses of functions.
+
+```css
+a { transform: translate( 1, 1 ); }
+/** ↑ ↑
+ * The space inside these two parentheses */
+```
+
+## Options
+
+`string`: `"always"|"never"|"always-single-line"|"never-single-line"`
+
+### `"always"`
+
+There *must always* be a single space inside the parentheses.
+
+The following patterns are considered violations:
+
+```css
+a { transform: translate(1, 1); }
+```
+
+```css
+a { transform: translate(1, 1 ); }
+```
+
+The following patterns are *not* considered violations:
+
+```css
+a { transform: translate( 1, 1 ); }
+```
+
+### `"never"`
+
+There *must never* be whitespace on the inside the parentheses.
+
+The following patterns are considered violations:
+
+```css
+a { transform: translate( 1, 1 ); }
+```
+
+```css
+a { transform: translate(1, 1 ); }
+```
+
+The following patterns are *not* considered violations:
+
+```css
+a { transform: translate(1, 1); }
+```
+
+### `"always-single-line"`
+
+There *must always* be a single space inside the parentheses of single-line functions.
+
+The following patterns are considered violations:
+
+```css
+a { transform: translate(1, 1) }
+```
+
+```css
+a { transform: translate(1, 1 ) }
+```
+
+The following patterns are *not* considered violations:
+
+```css
+a { transform: translate( 1, 1 ) }
+```
+
+```css
+a { transform: translate(1,
+ 1) }
+```
+
+```css
+a {
+ transform: translate(
+ 1,
+ 1
+ )
+}
+```
+
+### `"never-single-line"`
+
+There *must never* be whitespace inside the parentheses of single-line functions.
+
+The following patterns are considered violations:
+
+```css
+a { transform: translate( 1, 1 ) }
+```
+
+```css
+a { transform: translate(1, 1 ) }
+```
+
+The following patterns are *not* considered violations:
+
+```css
+a { transform: translate(1, 1) }
+```
+
+```css
+a { transform: translate( 1,
+ 1) }
+```
+
+```css
+a {
+ transform: translate(
+ 1,
+ 1
+ )
+}
+```