--- /dev/null
+# color-no-invalid-hex
+
+Disallow invalid hex colors.
+
+```css
+a { color: #y3 }
+/** ↑
+ * These hex colors */
+```
+
+Longhand hex colors can be either 6 or 8 (with alpha channel) hexadecimal characters. And their shorthand variants are 3 and 4 characters respectively.
+
+## Options
+
+### `true`
+
+The following patterns are considered violations:
+
+```css
+a { color: #00; }
+```
+
+```css
+a { color: #fff1az; }
+```
+
+```css
+a { color: #12345aa; }
+```
+
+The following patterns are *not* considered violations:
+
+```css
+a { color: #000; }
+```
+
+```css
+a { color: #000f; }
+```
+
+```css
+a { color: #fff1a0; }
+```
+
+```css
+a { color: #123450aa; }
+```