Prevent inherited styles on next/image wrapper or sizer (#30064)

As a follow up to #30041 which changed `<div>` to `<span>`, this PR makes sure that unexpected styles are not applied to the image wrapper or sizer spans.

For example: `.content span {}` would apply to all spans and incorrectly style the image wrapper.

This PR adds [`all: initial`](https://developer.mozilla.org/en-US/docs/Web/CSS/all) to effectively reset the span styles.

packages/next/client/image.tsx

@@ -458,10 +458,19 @@ export default function Image({
   })
   const isVisible = !isLazy || isIntersected
 
-  let wrapperStyle: JSX.IntrinsicElements['span']['style'] | undefined
-  let sizerStyle: JSX.IntrinsicElements['span']['style'] | undefined
+  const wrapperStyle: JSX.IntrinsicElements['span']['style'] = {
+    all: 'initial',
+    boxSizing: 'border-box',
+    overflow: 'hidden',
+  }
+  const sizerStyle: JSX.IntrinsicElements['span']['style'] = {
+    all: 'initial',
+    boxSizing: 'border-box',
+    display: 'block',
+  }
+  let hasSizer = false
   let sizerSvg: string | undefined
-  let imgStyle: ImgElementStyle | undefined = {
+  const imgStyle: ImgElementStyle = {
     position: 'absolute',
     top: 0,
     left: 0,
@@ -495,19 +504,12 @@ export default function Image({
       : {}
   if (layout === 'fill') {
     // <Image src="i.png" layout="fill" />
-    wrapperStyle = {
-      display: 'block',
-      overflow: 'hidden',
-
-      position: 'absolute',
-      top: 0,
-      left: 0,
-      bottom: 0,
-      right: 0,
-
-      boxSizing: 'border-box',
-      margin: 0,
-    }
+    wrapperStyle.display = 'block'
+    wrapperStyle.position = 'absolute'
+    wrapperStyle.top = 0
+    wrapperStyle.left = 0
+    wrapperStyle.bottom = 0
+    wrapperStyle.right = 0
   } else if (
     typeof widthInt !== 'undefined' &&
     typeof heightInt !== 'undefined'
@@ -517,41 +519,24 @@ export default function Image({
     const paddingTop = isNaN(quotient) ? '100%' : `${quotient * 100}%`
     if (layout === 'responsive') {
       // <Image src="i.png" width="100" height="100" layout="responsive" />
-      wrapperStyle = {
-        display: 'block',
-        overflow: 'hidden',
-        position: 'relative',
-
-        boxSizing: 'border-box',
-        margin: 0,
-      }
-      sizerStyle = { display: 'block', boxSizing: 'border-box', paddingTop }
+      wrapperStyle.display = 'block'
+      wrapperStyle.position = 'relative'
+      hasSizer = true
+      sizerStyle.paddingTop = paddingTop
     } else if (layout === 'intrinsic') {
       // <Image src="i.png" width="100" height="100" layout="intrinsic" />
-      wrapperStyle = {
-        display: 'inline-block',
-        maxWidth: '100%',
-        overflow: 'hidden',
-        position: 'relative',
-        boxSizing: 'border-box',
-        margin: 0,
-      }
-      sizerStyle = {
-        display: 'block',
-        boxSizing: 'border-box',
-        maxWidth: '100%',
-      }
+      wrapperStyle.display = 'inline-block'
+      wrapperStyle.position = 'relative'
+      wrapperStyle.maxWidth = '100%'
+      hasSizer = true
+      sizerStyle.maxWidth = '100%'
       sizerSvg = `<svg width="${widthInt}" height="${heightInt}" xmlns="http://www.w3.org/2000/svg" version="1.1"/>`
     } else if (layout === 'fixed') {
       // <Image src="i.png" width="100" height="100" layout="fixed" />
-      wrapperStyle = {
-        display: 'inline-block',
-        overflow: 'hidden',
-        boxSizing: 'border-box',
-        position: 'relative',
-        width: widthInt,
-        height: heightInt,
-      }
+      wrapperStyle.display = 'inline-block'
+      wrapperStyle.position = 'relative'
+      wrapperStyle.width = widthInt
+      wrapperStyle.height = heightInt
     }
   } else {
     // <Image src="i.png" />
@@ -584,11 +569,12 @@ export default function Image({
 
   return (
     <span style={wrapperStyle}>
-      {sizerStyle ? (
+      {hasSizer ? (
         <span style={sizerStyle}>
           {sizerSvg ? (
             <img
               style={{
+                all: 'initial',
                 maxWidth: '100%',
                 display: 'block',
                 margin: 0,

test/integration/image-component/default/pages/style-inheritance.js

@@ -0,0 +1,42 @@
+import React from 'react'
+import Image from 'next/image'
+import style from '../style.module.css'
+
+const Page = () => {
+  return (
+    <div id="main-container" className={style.mainContainer}>
+      <h1>Image Style Inheritance</h1>
+      <Image
+        id="img-fixed"
+        layout="fixed"
+        src="/test.jpg"
+        width="400"
+        height="400"
+      />
+
+      <Image
+        id="img-intrinsic"
+        layout="intrinsic"
+        src="/test.jpg"
+        width="400"
+        height="400"
+      />
+
+      <div style={{ position: 'relative', width: '200px', height: '200px' }}>
+        <Image id="img-fill" layout="fill" src="/test.jpg" objectFit="cover" />
+      </div>
+
+      <Image
+        id="img-responsive"
+        layout="responsive"
+        src="/test.jpg"
+        width="400"
+        height="400"
+      />
+
+      <footer>Footer</footer>
+    </div>
+  )
+}
+
+export default Page

test/integration/image-component/default/style.module.css

@@ -1,3 +1,15 @@
 .displayFlex {
   display: flex;
 }
+
+.mainContainer {
+  border-radius: 75px;
+}
+
+.mainContainer span {
+  border-radius: 50px;
+}
+
+.mainContainer img {
+  border-radius: 100px;
+}

test/integration/image-component/default/test/index.test.js

@@ -699,6 +699,46 @@ function runTests(mode) {
     }
   })
 
+  it('should apply style inheritance for img elements but not wrapper elements', async () => {
+    let browser
+    try {
+      browser = await webdriver(appPort, '/style-inheritance')
+
+      await browser.eval(
+        `document.querySelector("footer").scrollIntoView({behavior: "smooth"})`
+      )
+
+      const allImgs = await browser.eval(`
+        function foo() {
+          const imgs = document.querySelectorAll("img[id]");
+          for (let img of imgs) {
+            const br = window.getComputedStyle(img).getPropertyValue("border-radius");
+            if (!br) return 'no-border-radius';
+            if (br !== '100px') return br;
+          }
+          return true;
+        }()
+      `)
+      expect(allImgs).toBe(true)
+
+      const allSpans = await browser.eval(`
+        function foo() {
+          const spans = document.querySelectorAll("span");
+          for (let span of spans) {
+            const br = window.getComputedStyle(span).getPropertyValue("border-radius");
+            if (br && br !== '0px') return br;
+          }
+          return false;
+        }()
+      `)
+      expect(allSpans).toBe(false)
+    } finally {
+      if (browser) {
+        await browser.close()
+      }
+    }
+  })
+
   // Tests that use the `unsized` attribute:
   if (mode !== 'dev') {
     it('should correctly rotate image', async () => {