fix(SelectDropdown): adding optional zIndex prop

packages/gamut/src/Form/SelectDropdown/SelectDropdown.tsx

@@ -122,6 +122,7 @@ export const SelectDropdown: React.FC<SelectDropdownProps> = ({
   shownOptionsLimit = 6,
   size,
   value,
+  zIndex,
   ...rest
 }) => {
   const rawInputId = useId();
@@ -243,8 +244,8 @@ export const SelectDropdown: React.FC<SelectDropdownProps> = ({
 
   const theme = useTheme();
   const memoizedStyles = useMemo((): StylesConfig<any, false> => {
-    return getMemoizedStyles(theme);
-  }, [theme]);
+    return getMemoizedStyles(theme, zIndex);
+  }, [theme, zIndex]);
 
   return (
     <SelectDropdownContext.Provider

packages/gamut/src/Form/SelectDropdown/styles.ts

@@ -61,15 +61,16 @@ const dropdownBorderStates = states({
   error: { borderColorTop: 'feedback-error' },
 });
 
-const dropdownBorderStyles = css({
-  ...formBaseComponentStyles,
-  border: 1,
-  borderColor: 'currentColor',
-  position: 'absolute',
-  marginTop: 0,
-  borderRadius: 'none',
-  zIndex: 2,
-});
+const dropdownBorderStyles = (zIndex = 2) =>
+  css({
+    ...formBaseComponentStyles,
+    border: 1,
+    borderColor: 'currentColor',
+    position: 'absolute',
+    marginTop: 0,
+    borderRadius: 'none',
+    zIndex,
+  });
 
 const getOptionBackground = (isSelected: boolean, isFocused: boolean) =>
   css({
@@ -89,7 +90,8 @@ const placeholderColor = css({
 });
 
 export const getMemoizedStyles = (
-  theme: typeof GamutTheme
+  theme: typeof GamutTheme,
+  zIndex?: number
 ): StylesConfig<any, false> => {
   return {
     clearIndicator: (provided) => ({
@@ -146,7 +148,7 @@ export const getMemoizedStyles = (
 
       return {
         ...provided,
-        ...dropdownBorderStyles({ theme }),
+        ...dropdownBorderStyles(zIndex)({ theme }),
         ...dropdownBorderStates({ error: state.selectProps.error, theme }),
         ...(dropdownWidth
           ? {

packages/gamut/src/Form/SelectDropdown/types/styles.ts

@@ -23,6 +23,8 @@ export interface SharedProps extends InternalInputsProps, SelectDropdownSizes {
    * This is only relevant when the dropdown width is set to be larger or smaller than the input width.
    */
   menuAlignment?: 'left' | 'right';
+  /** Z-index for the dropdown menu */
+  zIndex?: number;
 }
 
 /**

packages/styleguide/src/lib/Atoms/FormInputs/SelectDropdown/SelectDropdown.mdx

@@ -20,7 +20,6 @@ export const parameters = {
 };
 
 <Meta of={SelectDropdownStories} />
-
 <ComponentHeader {...parameters} />
 
 ## Usage
@@ -199,6 +198,14 @@ When using different widths for the input and dropdown, you can control how the
 
 <Canvas of={SelectDropdownStories.MenuAlignmentRight} />
 
+### Selectdropdown options menu z-index
+
+You can control the z-index of the dropdown menu using the `zIndex` prop. This is useful when you have other elements on the page that might overlap with the dropdown.
+
+In the example below, the z-index menu is configured to the default value (`auto`) and `5` respectively. The DataTable below the `SelectDropdown` has a z-index of `2` since it's sticky and intended to float above other content.
+
+<Canvas of={SelectDropdownStories.zIndexOnMenu} />
+
 ## Multiple select
 
 <Canvas of={SelectDropdownStories.MultipleSelect} />

packages/styleguide/src/lib/Atoms/FormInputs/SelectDropdown/SelectDropdown.stories.tsx

@@ -1,4 +1,11 @@
-import { Box, FlexBox, FormGroup, SelectDropdown } from '@codecademy/gamut';
+import {
+  Box,
+  DataList,
+  FlexBox,
+  FormGroup,
+  SelectDropdown,
+  Text,
+} from '@codecademy/gamut';
 import { RadarIcon, ResponsiveIcon, RocketIcon } from '@codecademy/gamut-icons';
 import type { Meta, StoryObj } from '@storybook/react';
 
@@ -995,3 +1002,64 @@ export const LongPlaceholderAgain: Story = {
     </Box>
   ),
 };
+
+export const zIndexOnMenu: Story = {
+  render: (args) => (
+    <FlexBox column height="500px">
+      <Text mb={16}>Notice how the menu renders based on using zIndex</Text>
+      <FlexBox gap={16}>
+        <FormGroup
+          htmlFor="usesDefaultZIndex"
+          isSoloField
+          label="This menu is rendered behind the header"
+        >
+          <SelectDropdown
+            name="usesDefaultZIndex"
+            options={args.options}
+            placeholder="Uses the default zIndex of 2"
+          />
+        </FormGroup>
+        <FormGroup
+          htmlFor="hasSetZIndex"
+          isSoloField
+          label="This menu floats above the table's header"
+        >
+          <SelectDropdown
+            name="hasSetZIndex"
+            options={args.options}
+            placeholder="Has a zIndex of 5"
+            zIndex={5}
+          />
+        </FormGroup>
+      </FlexBox>
+      <DataList
+        columns={[
+          {
+            header: 'Name',
+            key: 'name',
+            size: 'lg',
+            type: 'header',
+            sortable: true,
+          },
+          { header: 'Rank', key: 'role', size: 'lg', sortable: true },
+          { header: 'Ship', key: 'ship', size: 'lg', sortable: true },
+        ]}
+        disableContainerQuery
+        id="crew"
+        idKey="name"
+        rows={[
+          {
+            name: 'Jean Luc Picard',
+            role: 'Captain',
+            ship: 'USS Enterprise',
+          },
+          {
+            name: 'Wesley Crusher',
+            role: 'Deus Ex Machina',
+            ship: 'USS Enterprise',
+          },
+        ]}
+      />
+    </FlexBox>
+  ),
+};