diff --git a/editor/libeditor/HTMLEditSubActionHandler.cpp b/editor/libeditor/HTMLEditSubActionHandler.cpp
index 2a409b6884aa..6aafcd8f5a3a 100644
--- a/editor/libeditor/HTMLEditSubActionHandler.cpp
+++ b/editor/libeditor/HTMLEditSubActionHandler.cpp
@@ -9028,7 +9028,87 @@ nsresult HTMLEditor::GetInlineStyles(
   MOZ_ASSERT(IsEditActionDataAvailable());
   MOZ_ASSERT(aPendingStyleCacheArray.IsEmpty());
 
-  bool useCSS = IsCSSEnabled();
+  if (!IsCSSEnabled()) {
+    // In the HTML styling mode, we should preserve the order of inline styles
+    // specified with HTML elements, then, we can keep same order as original
+    // one when we create new elements to apply the styles at new place.
+    // XXX Currently, we don't preserve all inline parents, therefore, we cannot
+    //     restore all inline elements as-is.  Perhaps, we should store all
+    //     inline elements with more details (e.g., all attributes), and store
+    //     same elements.  For example, web apps may give style as:
+    //     em {
+    //       font-style: italic;
+    //     }
+    //     em em {
+    //       font-style: normal;
+    //       font-weight: bold;
+    //     }
+    //     but we cannot restore the style as-is.
+    nsString value;
+    const bool givenElementIsEditable =
+        HTMLEditUtils::IsSimplyEditableNode(aElement);
+    auto NeedToAppend = [&](nsStaticAtom& aTagName, nsStaticAtom* aAttribute) {
+      if (mPendingStylesToApplyToNewContent->GetStyleState(
+              aTagName, aAttribute) != PendingStyleState::NotUpdated) {
+        return false;  // The style has already been changed.
+      }
+      if (aPendingStyleCacheArray.Contains(aTagName, aAttribute)) {
+        return false;  // Already preserved
+      }
+      return true;
+    };
+    for (Element* const inclusiveAncestor :
+         aElement.InclusiveAncestorsOfType<Element>()) {
+      if (HTMLEditUtils::IsBlockElement(*inclusiveAncestor) ||
+          (givenElementIsEditable &&
+           !HTMLEditUtils::IsSimplyEditableNode(*inclusiveAncestor))) {
+        break;
+      }
+      if (inclusiveAncestor->IsAnyOfHTMLElements(
+              nsGkAtoms::b, nsGkAtoms::i, nsGkAtoms::u, nsGkAtoms::s,
+              nsGkAtoms::strike, nsGkAtoms::tt, nsGkAtoms::em,
+              nsGkAtoms::strong, nsGkAtoms::dfn, nsGkAtoms::code,
+              nsGkAtoms::samp, nsGkAtoms::var, nsGkAtoms::cite, nsGkAtoms::abbr,
+              nsGkAtoms::acronym, nsGkAtoms::sub, nsGkAtoms::sup)) {
+        nsStaticAtom& tagName = const_cast<nsStaticAtom&>(
+            *inclusiveAncestor->NodeInfo()->NameAtom()->AsStatic());
+        if (NeedToAppend(tagName, nullptr)) {
+          aPendingStyleCacheArray.AppendElement(
+              PendingStyleCache(tagName, nullptr, EmptyString()));
+        }
+        continue;
+      }
+      if (inclusiveAncestor->IsHTMLElement(nsGkAtoms::font)) {
+        if (NeedToAppend(*nsGkAtoms::font, nsGkAtoms::face)) {
+          inclusiveAncestor->GetAttr(kNameSpaceID_None, nsGkAtoms::face, value);
+          if (!value.IsEmpty()) {
+            aPendingStyleCacheArray.AppendElement(
+                PendingStyleCache(*nsGkAtoms::font, nsGkAtoms::face, value));
+            value.Truncate();
+          }
+        }
+        if (NeedToAppend(*nsGkAtoms::font, nsGkAtoms::size)) {
+          inclusiveAncestor->GetAttr(kNameSpaceID_None, nsGkAtoms::size, value);
+          if (!value.IsEmpty()) {
+            aPendingStyleCacheArray.AppendElement(
+                PendingStyleCache(*nsGkAtoms::font, nsGkAtoms::size, value));
+            value.Truncate();
+          }
+        }
+        if (NeedToAppend(*nsGkAtoms::font, nsGkAtoms::color)) {
+          inclusiveAncestor->GetAttr(kNameSpaceID_None, nsGkAtoms::color,
+                                     value);
+          if (!value.IsEmpty()) {
+            aPendingStyleCacheArray.AppendElement(
+                PendingStyleCache(*nsGkAtoms::font, nsGkAtoms::color, value));
+            value.Truncate();
+          }
+        }
+        continue;
+      }
+    }
+    return NS_OK;
+  }
 
   for (nsStaticAtom* property : {nsGkAtoms::b,
                                  nsGkAtoms::i,
@@ -9067,7 +9147,7 @@ nsresult HTMLEditor::GetInlineStyles(
     nsString value;  // Don't use nsAutoString here because it requires memcpy
                      // at creating new PendingStyleCache instance.
     // Don't use CSS for <font size>, we don't support it usefully (bug 780035)
-    if (!useCSS || (property == nsGkAtoms::size)) {
+    if (property == nsGkAtoms::size) {
       isSet = HTMLEditUtils::IsInlineStyleSetByElement(aElement, style, nullptr,
                                                        &value);
     } else if (style.IsCSSEditable(aElement)) {
diff --git a/editor/libeditor/PendingStyles.h b/editor/libeditor/PendingStyles.h
index 368802f2ee00..e8c5d01057f6 100644
--- a/editor/libeditor/PendingStyles.h
+++ b/editor/libeditor/PendingStyles.h
@@ -105,8 +105,8 @@ class PendingStyleCache final {
 class MOZ_STACK_CLASS AutoPendingStyleCacheArray final
     : public AutoTArray<PendingStyleCache, 21> {
  public:
-  index_type IndexOf(const nsStaticAtom& aTag,
-                     const nsStaticAtom* aAttribute) const {
+  [[nodiscard]] index_type IndexOf(const nsStaticAtom& aTag,
+                                   const nsStaticAtom* aAttribute) const {
     for (index_type index = 0; index < Length(); ++index) {
       const PendingStyleCache& styleCache = ElementAt(index);
       if (&styleCache.TagRef() == &aTag &&
@@ -116,6 +116,11 @@ class MOZ_STACK_CLASS AutoPendingStyleCacheArray final
     }
     return NoIndex;
   }
+
+  [[nodiscard]] bool Contains(const nsStaticAtom& aTag,
+                              const nsStaticAtom* aAttribute) const {
+    return IndexOf(aTag, aAttribute) != NoIndex;
+  }
 };
 
 enum class PendingStyleState {
diff --git a/testing/web-platform/meta/editing/run/inserttext.html.ini b/testing/web-platform/meta/editing/run/inserttext.html.ini
index b654a68d1842..2b5a76cf7b2f 100644
--- a/testing/web-platform/meta/editing/run/inserttext.html.ini
+++ b/testing/web-platform/meta/editing/run/inserttext.html.ini
@@ -330,9 +330,6 @@
   [[["inserttext","d"\],["inserttext","e"\],["inserttext","f"\]\] "<div>abc{<b><i>def</i></b>}ghi</div>" compare innerHTML]
     expected: FAIL
 
-  [[["inserttext","d"\],["inserttext","e"\],["inserttext","f"\]\] "<div>abc[<b><i>def\]</i></b>ghi</div>" compare innerHTML]
-    expected: FAIL
-
   [[["inserttext","d"\],["inserttext","e"\],["inserttext","f"\],["inserttext","g"\]\] "<div>abc[<b><i>def</i></b>g\]hi</div>" compare innerHTML]
     expected: FAIL
 
@@ -347,15 +344,3 @@
 
   [[["inserttext","c"\],["inserttext","d"\],["inserttext","e"\]\] "<div>ab[c<b><i>de\]f</i></b>ghi</div>" compare innerHTML]
     expected: FAIL
-
-  [[["inserttext","d"\],["inserttext","e"\]\] "<div>abc[<b><i>de\]f</i></b>ghi</div>" compare innerHTML]
-    expected: FAIL
-
-  [[["inserttext","d"\],["inserttext","e"\]\] "<div>abc{<b><i>de\]f</i></b>ghi</div>" compare innerHTML]
-    expected: FAIL
-
-  [[["inserttext","d"\],["inserttext","e"\]\] "<div>abc[<s></s><b><i>de\]f</i></b>ghi</div>" compare innerHTML]
-    expected: FAIL
-
-  [[["inserttext","d"\],["inserttext","e"\]\] "<div>abc{<s></s><b><i>de\]f</i></b>ghi</div>" compare innerHTML]
-    expected: FAIL
diff --git a/testing/web-platform/meta/editing/run/multitest.html.ini b/testing/web-platform/meta/editing/run/multitest.html.ini
index 2ef6f09352a6..535ef516c10b 100644
--- a/testing/web-platform/meta/editing/run/multitest.html.ini
+++ b/testing/web-platform/meta/editing/run/multitest.html.ini
@@ -1144,27 +1144,12 @@
   [[["forwarddelete",""\],["inserttext","d"\],["inserttext","e"\],["inserttext","f"\]\] "<div>abc{<b><i>def</i></b>}ghi</div>" compare innerHTML]
     expected: FAIL
 
-  [[["delete",""\],["inserttext","d"\],["inserttext","e"\],["inserttext","f"\]\] "<div>abc<b><i>[def\]</i></b>ghi</div>" compare innerHTML]
-    expected: FAIL
-
-  [[["forwarddelete",""\],["inserttext","d"\],["inserttext","e"\],["inserttext","f"\]\] "<div>abc<b><i>[def\]</i></b>ghi</div>" compare innerHTML]
-    expected: FAIL
-
   [[["delete",""\],["inserttext","d"\],["inserttext","e"\],["inserttext","f"\]\] "<div>abc[<b><i>def\]</i></b>ghi</div>" compare innerHTML]
     expected: FAIL
 
-  [[["forwarddelete",""\],["inserttext","d"\],["inserttext","e"\],["inserttext","f"\]\] "<div>abc[<b><i>def\]</i></b>ghi</div>" compare innerHTML]
-    expected: FAIL
-
-  [[["delete",""\],["inserttext","d"\],["inserttext","e"\],["inserttext","f"\]\] "<div>abc<b><i>[def</i></b>\]ghi</div>" compare innerHTML]
-    expected: FAIL
-
   [[["forwarddelete",""\],["inserttext","d"\],["inserttext","e"\],["inserttext","f"\]\] "<div>abc<b><i>[def</i></b>\]ghi</div>" compare innerHTML]
     expected: FAIL
 
-  [[["delete",""\],["inserttext","d"\],["inserttext","e"\],["inserttext","f"\],["inserttext","g"\]\] "<div>abc<b><i>[def</i></b>g\]hi</div>" compare innerHTML]
-    expected: FAIL
-
   [[["forwarddelete",""\],["inserttext","d"\],["inserttext","e"\],["inserttext","f"\],["inserttext","g"\]\] "<div>abc<b><i>[def</i></b>g\]hi</div>" compare innerHTML]
     expected: FAIL
 
@@ -1183,12 +1168,6 @@
   [[["insertparagraph",""\],["inserttext","d"\],["inserttext","e"\],["inserttext","f"\]\] "<div>abc{<b><i>def</i></b>}ghi</div>" compare innerHTML]
     expected: FAIL
 
-  [[["insertparagraph",""\],["inserttext","d"\],["inserttext","e"\],["inserttext","f"\]\] "<div>abc<b><i>[def\]</i></b>ghi</div>" compare innerHTML]
-    expected: FAIL
-
-  [[["insertparagraph",""\],["inserttext","d"\],["inserttext","e"\],["inserttext","f"\]\] "<div>abc[<b><i>def\]</i></b>ghi</div>" compare innerHTML]
-    expected: FAIL
-
   [[["insertparagraph",""\],["inserttext","d"\],["inserttext","e"\],["inserttext","f"\]\] "<div>abc<b><i>[def</i></b>\]ghi</div>" compare innerHTML]
     expected: FAIL
 
@@ -1210,9 +1189,6 @@
   [[["forwarddelete",""\],["inserttext","d"\],["inserttext","e"\],["inserttext","f"\]\] "<div>abc[<b><i><img src=\\"/img/lion.svg\\">def\]</i></b>ghi</div>" compare innerHTML]
     expected: FAIL
 
-  [[["insertlinebreak",""\],["inserttext","d"\],["inserttext","e"\]\] "<div>abc[<b><i><img src=\\"/img/lion.svg\\">de\]f</i></b>ghi</div>" compare innerHTML]
-    expected: FAIL
-
   [[["insertparagraph",""\],["inserttext","d"\],["inserttext","e"\],["inserttext","f"\]\] "<div>abc[<b><i><img src=\\"/img/lion.svg\\">def\]</i></b>ghi</div>" compare innerHTML]
     expected: FAIL
 
@@ -1225,9 +1201,6 @@
   [[["forwarddelete",""\],["inserttext","c"\],["inserttext","d"\],["inserttext","e"\]\] "<div>ab[c<b><i>de\]f</i></b>ghi</div>" compare innerHTML]
     expected: FAIL
 
-  [[["insertlinebreak",""\],["inserttext","c"\],["inserttext","d"\],["inserttext","e"\]\] "<div>ab[c<b><i>de\]f</i></b>ghi</div>" compare innerHTML]
-    expected: FAIL
-
   [[["delete",""\],["inserttext","d"\],["inserttext","e"\]\] "<div>abc[<b><i>de\]f</i></b>ghi</div>" compare innerHTML]
     expected: FAIL
 
@@ -1240,12 +1213,6 @@
   [[["forwarddelete",""\],["inserttext","d"\],["inserttext","e"\]\] "<div>abc{<b><i>de\]f</i></b>ghi</div>" compare innerHTML]
     expected: FAIL
 
-  [[["insertlinebreak",""\],["inserttext","d"\],["inserttext","e"\]\] "<div>abc[<b><i>de\]f</i></b>ghi</div>" compare innerHTML]
-    expected: FAIL
-
-  [[["insertlinebreak",""\],["inserttext","d"\],["inserttext","e"\]\] "<div>abc{<b><i>de\]f</i></b>ghi</div>" compare innerHTML]
-    expected: FAIL
-
   [[["delete",""\],["inserttext","d"\],["inserttext","e"\]\] "<div>abc[<s></s><b><i>de\]f</i></b>ghi</div>" compare innerHTML]
     expected: FAIL
 
@@ -1257,9 +1224,3 @@
 
   [[["forwarddelete",""\],["inserttext","d"\],["inserttext","e"\]\] "<div>abc{<s></s><b><i>de\]f</i></b>ghi</div>" compare innerHTML]
     expected: FAIL
-
-  [[["insertlinebreak",""\],["inserttext","d"\],["inserttext","e"\]\] "<div>abc[<s></s><b><i>de\]f</i></b>ghi</div>" compare innerHTML]
-    expected: FAIL
-
-  [[["insertlinebreak",""\],["inserttext","d"\],["inserttext","e"\]\] "<div>abc{<s></s><b><i>de\]f</i></b>ghi</div>" compare innerHTML]
-    expected: FAIL
diff --git a/testing/web-platform/tests/editing/data/multitest.js b/testing/web-platform/tests/editing/data/multitest.js
index b1259afcbf61..135f133ebc34 100644
--- a/testing/web-platform/tests/editing/data/multitest.js
+++ b/testing/web-platform/tests/editing/data/multitest.js
@@ -2481,27 +2481,20 @@ var browserTests = [
     [["styleWithCSS", "false"],["bold",""],["inserttext","d"]],
     ["<div><b><i>abc</i></b><i>d</i></div>",
      "<div><b><i>abc</i></b><i>d<br></i></div>",
-     "<div><b><i>abc</i></b><i>d</i><br></div>",
-     "<div><i><b>abc</b>d</i></div>",
-     "<div><i><b>abc</b>d<br></i></div>",
-     "<div><i><b>abc</b>d</i><br></div>"],
+     "<div><b><i>abc</i></b><i>d</i><br></div>"],
     [true,true,true],
     {"bold":[false,true,"",false,false,""]}],
 ["<div><b><i>abc[]</i><br></b></div>",
     [["styleWithCSS", "false"],["bold",""],["inserttext","d"]],
     ["<div><b><i>abc</i></b><i>d</i></div>",
      "<div><b><i>abc</i></b><i>d<br></i></div>",
-     "<div><b><i>abc</i></b><i>d</i><br></div>",
-     "<div><i><b>abc</b>d</i></div>",
-     "<div><i><b>abc</b>d<br></i></div>",
-     "<div><i><b>abc</b>d</i><br></div>"],
+     "<div><b><i>abc</i></b><i>d</i><br></div>"],
     [true,true,true],
     {"bold":[false,true,"",false,false,""]}],
 // In this case, second line text should be keep bold style.
 ["<div><b><i>abc[]<br></i><br></b></div>",
     [["styleWithCSS", "false"],["bold",""],["inserttext","d"]],
-    ["<div><b><i>abc</i></b><i>d<br></i><b><br></b></div>",
-     "<div><i><b>abc</b>d<br></i><b><br></b></div>"],
+    "<div><b><i>abc</i></b><i>d<br></i><b><br></b></div>",
     [true,true,true],
     {"bold":[false,true,"",false,false,""]}],
 // Tests putting caret to right paragraph at insert paragraph, and preserve