📝 Update CSS custom properties link

packages/dropdown/README.md

@@ -27,7 +27,7 @@ The three primary design goals for the existence of this component:
        and the value of that item at the same time (otherwise, the value is
        the text content of the dropdown item element)
     4. To style your dropdowns, use CSS; there are a
-       [collection of CSS variables](https://github.com/acusti/uikit/blob/main/packages/dropdown/src/styles.ts#L17-L27)
+       [collection of CSS custom properties](https://github.com/acusti/uikit/blob/main/packages/dropdown/src/styles.ts#L21-L32)
        used internally to style them if that works best for you, or just
        override the minimal default CSS as appropriate
 3. Lightweight bundle size with the bare minimum of dependencies (see