[input] Fix high contrast cutoff on first character (@silviuaavram)

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

@@ -124,7 +124,7 @@ const FilledInputRoot = styled(InputBaseRoot, {
               }`,
               left: 0,
               bottom: 0,
-              content: '"\\00a0"',
+              content: '""',
               position: 'absolute',
               right: 0,
               transition: theme.transitions.create('border-bottom-color', {

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

@@ -97,7 +97,7 @@ const InputRoot = styled(InputBaseRoot, {
               borderBottom: `1px solid ${bottomLineColor}`,
               left: 0,
               bottom: 0,
-              content: '"\\00a0"',
+              content: '""',
               position: 'absolute',
               right: 0,
               transition: theme.transitions.create('border-bottom-color', {

test/regressions/fixtures/TextField/StandardTextField.js

@@ -0,0 +1,21 @@
+import * as React from 'react';
+import TextField from '@mui/material/TextField';
+
+export default function StandardTextField() {
+  return (
+    <div>
+      <div>
+        <TextField label="Standard" variant="standard" />
+        <TextField label="Standard disabled" variant="standard" disabled />
+        <TextField label="Standard error" variant="standard" error />
+        <TextField label="Standard required" variant="standard" required />
+      </div>
+      <div>
+        <TextField value="Material" label="Standard" variant="standard" />
+        <TextField value="Material" label="Standard disabled" variant="standard" disabled />
+        <TextField value="Material" label="Standard error" variant="standard" error />
+        <TextField value="Material" label="Standard required" variant="standard" required />
+      </div>
+    </div>
+  );
+}

test/regressions/index.test.js

@@ -160,6 +160,21 @@ async function main() {
       });
     });
 
+    describe('TextField', () => {
+      it('should render standard variant correctly in forced-colors mode', async () => {
+        await page.emulateMedia({ forcedColors: 'active' });
+        try {
+          const testcase = await renderFixture('/regression-TextField/StandardTextField');
+          await takeScreenshot({
+            testcase,
+            route: '/regression-TextField/StandardTextFieldForcedColors',
+          });
+        } finally {
+          await page.emulateMedia({ forcedColors: 'none' });
+        }
+      });
+    });
+
     describe('Textarea', () => {
       it('should keep input caret position at the end when adding a newline', async () => {
         await renderFixture('/regression-Textarea/TextareaAutosize');