contenteditable="false" on child elements is not respected consistently

Phenomenon

When a contenteditable region contains child elements with contenteditable="false", the behavior is inconsistent. Some browsers allow editing within these elements, while others correctly prevent it.

Reproduction example

1. Create a contenteditable div.
2. Inside it, add a child element with contenteditable="false":

   <div contenteditable="true">
     <p>Editable text</p>
     <p contenteditable="false">This should not be editable</p>
   </div>

3. Try to edit the text in the child element with contenteditable="false".
4. Observe whether editing is prevented.

Observed behavior

• In Chrome, child elements with contenteditable="false" may still be editable.
• The attribute is not consistently respected.
• Selection and editing may work within elements that should be read-only.

Expected behavior

• Elements with contenteditable="false" should not be editable.
• The attribute should be respected regardless of parent element state.
• Selection within read-only elements should be allowed, but editing should be prevented.