Restore scroll after 'show less' (#4056)

* Restore scroll after 'show less'

* Get the whole sandbox into view

beta/src/components/MDX/Sandpack/CustomPreset.tsx

@@ -3,12 +3,15 @@
  */
 
 import React from 'react';
+// @ts-ignore
+import {flushSync} from 'react-dom';
 import {
   useSandpack,
   useActiveCode,
   SandpackCodeEditor,
   SandpackThemeProvider,
 } from '@codesandbox/sandpack-react';
+import scrollIntoView from 'scroll-into-view-if-needed';
 
 import {IconChevron} from 'components/Icon/IconChevron';
 import {NavigationBar} from './NavigationBar';
@@ -23,6 +26,7 @@ export function CustomPreset({
   onReset: () => void;
 }) {
   const lineCountRef = React.useRef<{[key: string]: number}>({});
+  const containerRef = React.useRef<HTMLDivElement>(null);
   const {sandpack} = useSandpack();
   const {code} = useActiveCode();
   const [isExpanded, setIsExpanded] = React.useState(false);
@@ -43,7 +47,9 @@ export function CustomPreset({
 
   return (
     <>
-      <div className="shadow-lg dark:shadow-lg-dark rounded-lg">
+      <div
+        className="shadow-lg dark:shadow-lg-dark rounded-lg"
+        ref={containerRef}>
         <NavigationBar showDownload={isSingleFile} onReset={onReset} />
         <SandpackThemeProvider theme={CustomTheme}>
           <div
@@ -75,7 +81,19 @@ export function CustomPreset({
               <button
                 translate="yes"
                 className="flex text-base justify-between dark:border-card-dark bg-wash dark:bg-card-dark items-center z-10 rounded-t-none p-1 w-full order-2 xl:order-last border-b-1 relative top-0"
-                onClick={() => setIsExpanded((prevExpanded) => !prevExpanded)}>
+                onClick={() => {
+                  const nextIsExpanded = !isExpanded;
+                  flushSync(() => {
+                    setIsExpanded(nextIsExpanded);
+                  });
+                  if (!nextIsExpanded && containerRef.current !== null) {
+                    scrollIntoView(containerRef.current, {
+                      scrollMode: 'if-needed',
+                      block: 'nearest',
+                      inline: 'nearest',
+                    });
+                  }
+                }}>
                 <span className="flex p-2 focus:outline-none text-primary dark:text-primary-dark">
                   <IconChevron
                     className="inline mr-1.5 text-xl"