[CardActionArea] Add support for CSS variables (#32554)

docs/pages/experiments/material-ui/card-action-area.tsx

@@ -0,0 +1,86 @@
+import * as React from 'react';
+import {
+  Experimental_CssVarsProvider as CssVarsProvider,
+  useColorScheme,
+} from '@mui/material/styles';
+import CssBaseline from '@mui/material/CssBaseline';
+import Box from '@mui/material/Box';
+import Button from '@mui/material/Button';
+import Card from '@mui/material/Card';
+import CardActionArea from '@mui/material/CardActionArea';
+import CardContent from '@mui/material/CardContent';
+import CardMedia from '@mui/material/CardMedia';
+import Container from '@mui/material/Container';
+import Typography from '@mui/material/Typography';
+import Moon from '@mui/icons-material/DarkMode';
+import Sun from '@mui/icons-material/LightMode';
+
+const ColorSchemePicker = () => {
+  const { mode, setMode } = useColorScheme();
+  const [mounted, setMounted] = React.useState(false);
+  React.useEffect(() => {
+    setMounted(true);
+  }, []);
+  if (!mounted) {
+    return null;
+  }
+
+  return (
+    <Button
+      variant="outlined"
+      onClick={() => {
+        if (mode === 'light') {
+          setMode('dark');
+        } else {
+          setMode('light');
+        }
+      }}
+    >
+      {mode === 'light' ? <Moon /> : <Sun />}
+    </Button>
+  );
+};
+
+export default function CardActionAreaCssVars() {
+  return (
+    <CssVarsProvider>
+      <CssBaseline />
+      <Container sx={{ my: 5 }}>
+        <Box sx={{ pb: 2 }}>
+          <ColorSchemePicker />
+        </Box>
+        <Box
+          sx={{
+            display: 'grid',
+            gridTemplateColumns: 'repeat(auto-fill, minmax(256px, 1fr))',
+            gridAutoRows: 'minmax(160px, auto)',
+            gap: 2,
+            '& > div': {
+              placeSelf: 'center',
+            },
+          }}
+        >
+          <Card>
+            <CardActionArea>
+              <CardMedia
+                component="img"
+                height="140"
+                image="/static/images/cards/contemplative-reptile.jpg"
+                alt="green iguana"
+              />
+              <CardContent>
+                <Typography gutterBottom variant="h5" component="div">
+                  Lizard
+                </Typography>
+                <Typography variant="body2" color="text.secondary">
+                  Lizards are a widespread group of squamate reptiles, with over 6,000 species,
+                  ranging across all continents except Antarctica
+                </Typography>
+              </CardContent>
+            </CardActionArea>
+          </Card>
+        </Box>
+      </Container>
+    </CssVarsProvider>
+  );
+}

packages/mui-material/src/CardActionArea/CardActionArea.js

@@ -27,13 +27,13 @@ const CardActionAreaRoot = styled(ButtonBase, {
   textAlign: 'inherit',
   width: '100%',
   [`&:hover .${cardActionAreaClasses.focusHighlight}`]: {
-    opacity: theme.palette.action.hoverOpacity,
+    opacity: (theme.vars || theme).palette.action.hoverOpacity,
     '@media (hover: none)': {
       opacity: 0,
     },
   },
   [`&.${cardActionAreaClasses.focusVisible} .${cardActionAreaClasses.focusHighlight}`]: {
-    opacity: theme.palette.action.focusOpacity,
+    opacity: (theme.vars || theme).palette.action.focusOpacity,
   },
 }));