popup: Fix handling of align attr in HTML popups

- Fix accidentally-inverted condition that caused all align values to be ignored.
- Add "p" to list of tags that can have align attribute.

src/Toolkit/Toolkit/Internal/HtmlUtility.cs

@@ -351,9 +351,9 @@ internal static MarkupNode BuildDocumentTree(string snippet)
                     break;
             }
 
-            if (name is "div" or "td" or "th" or "tr")
+            if (name is "div" or "p" or "td" or "th" or "tr")
             {
-                if (!attr.TryGetValue("align", out var alignStr) && Enum.TryParse<HtmlAlignment>(alignStr, true, out var align))
+                if (attr.TryGetValue("align", out var alignStr) && Enum.TryParse<HtmlAlignment>(alignStr, true, out var align))
                     newNode.Alignment = align;
             }