refactor(theme-classic): clean up CSS of doc sidebar item (#6622)

* refactor(theme-classic): clean up doc sidebar item CSS

* Use link placeholder for Introduction category

* Use test pages for dogfooding

* Update sidebars.js

* Add another test case

packages/docusaurus-theme-classic/src/theme/DocSidebarItem/index.tsx

@@ -162,8 +162,6 @@ function DocSidebarItemCategory({
           className={clsx('menu__link', {
             'menu__link--sublist': collapsible && !href,
             'menu__link--active': isActive,
-            [styles.menuLinkText]: !collapsible,
-            [styles.hasHref]: !!hrefWithSSRFallback,
           })}
           onClick={
             collapsible

packages/docusaurus-theme-classic/src/theme/DocSidebarItem/styles.module.css

@@ -6,18 +6,6 @@
  */
 
 @media (min-width: 997px) {
-  .menuLinkText {
-    cursor: initial;
-  }
-
-  .menuLinkText:hover {
-    background: none;
-  }
-
-  .menuLinkText.hasHref {
-    cursor: pointer;
-  }
-
   .menuHtmlItem {
     padding: var(--ifm-menu-link-padding-vertical)
       var(--ifm-menu-link-padding-horizontal);

packages/docusaurus-theme-classic/src/theme/DocSidebarItems/styles.module.css

@@ -1,20 +0,0 @@
-/**
- * Copyright (c) Facebook, Inc. and its affiliates.
- *
- * This source code is licensed under the MIT license found in the
- * LICENSE file in the root directory of this source tree.
- */
-
-@media (min-width: 997px) {
-  .menuLinkText {
-    cursor: initial;
-  }
-
-  .menuLinkText:hover {
-    background: none;
-  }
-
-  .menuLinkText.hasHref {
-    cursor: pointer;
-  }
-}

website/_dogfooding/docs-tests-sidebars.js

@@ -40,6 +40,15 @@ const sidebars = {
       collapsible: false,
       items: ['index', 'more-test'],
     },
+    {
+      type: 'category',
+      label: 'Another category with index',
+      collapsible: false,
+      link: {
+        type: 'generated-index',
+      },
+      items: ['more-test'],
+    },
     {
       type: 'category',
       label: 'Huge sidebar category',
@@ -74,6 +83,8 @@ const sidebars = {
     {
       type: 'category',
       label: 'HTML items tests',
+      collapsed: false,
+      collapsible: false,
       items: [
         //  title
         {