diff --git a/lib/model/code_block.dart b/lib/model/code_block.dart
index 34c7c5506b..222981f6e1 100644
--- a/lib/model/code_block.dart
+++ b/lib/model/code_block.dart
@@ -174,7 +174,6 @@ enum CodeBlockSpanType {
 
 CodeBlockSpanType codeBlockSpanTypeFromClassName(String className) {
   return switch (className) {
-    '' => CodeBlockSpanType.text,
     'hll' => CodeBlockSpanType.highlightedLines,
     'w' => CodeBlockSpanType.whitespace,
     'esc' => CodeBlockSpanType.escape,
diff --git a/lib/model/content.dart b/lib/model/content.dart
index c22970a1aa..0b0bb502bb 100644
--- a/lib/model/content.dart
+++ b/lib/model/content.dart
@@ -577,22 +577,17 @@ class _ZulipContentParser {
 
     final dom.Element katexElement;
     if (!block) {
-      assert(element.localName == 'span'
-          && element.classes.length == 1
-          && element.classes.contains('katex'));
+      assert(element.localName == 'span' && element.className == 'katex');
 
       katexElement = element;
     } else {
-      assert(element.localName == 'span'
-          && element.classes.length == 1
-          && element.classes.contains('katex-display'));
+      assert(element.localName == 'span' && element.className == 'katex-display');
 
       if (element.nodes.length != 1) return null;
       final child = element.nodes.single;
       if (child is! dom.Element) return null;
       if (child.localName != 'span') return null;
-      if (child.classes.length != 1) return null;
-      if (!child.classes.contains('katex')) return null;
+      if (child.className != 'katex') return null;
       katexElement = child;
     }
 
@@ -602,8 +597,7 @@ class _ZulipContentParser {
     final child = katexElement.nodes.first;
     if (child is! dom.Element) return null;
     if (child.localName != 'span') return null;
-    if (child.classes.length != 1) return null;
-    if (!child.classes.contains('katex-mathml')) return null;
+    if (child.className != 'katex-mathml') return null;
 
     if (child.nodes.length != 1) return null;
     final grandchild = child.nodes.single;
@@ -638,7 +632,18 @@ class _ZulipContentParser {
     return result;
   }
 
-  static final _emojiClassRegexp = RegExp(r"^emoji(-[0-9a-f]+)*$");
+  static final _userMentionClassNameRegexp = () {
+    // This matches a class `user-mention` or `user-group-mention`,
+    // plus an optional class `silent`, appearing in either order.
+    const mentionClass = r"user(?:-group)?-mention";
+    return RegExp("^(?:$mentionClass(?: silent)?|silent $mentionClass)\$");
+  }();
+
+  static final _emojiClassNameRegexp = () {
+    const specificEmoji = r"emoji(?:-[0-9a-f]+)+";
+    return RegExp("^(?:emoji $specificEmoji|$specificEmoji emoji)\$");
+  }();
+  static final _emojiCodeFromClassNameRegexp = RegExp(r"emoji-([^ ]+)");
 
   InlineContentNode parseInlineContent(dom.Node node) {
     assert(_debugParserContext == _ParserContext.inline);
@@ -654,27 +659,25 @@ class _ZulipContentParser {
 
     final element = node;
     final localName = element.localName;
-    final classes = element.classes;
+    final className = element.className;
     List<InlineContentNode> nodes() => parseInlineContentList(element.nodes);
 
-    if (localName == 'br' && classes.isEmpty) {
+    if (localName == 'br' && className.isEmpty) {
       return LineBreakInlineNode(debugHtmlNode: debugHtmlNode);
     }
-    if (localName == 'strong' && classes.isEmpty) {
+    if (localName == 'strong' && className.isEmpty) {
       return StrongNode(nodes: nodes(), debugHtmlNode: debugHtmlNode);
     }
-    if (localName == 'em' && classes.isEmpty) {
+    if (localName == 'em' && className.isEmpty) {
       return EmphasisNode(nodes: nodes(), debugHtmlNode: debugHtmlNode);
     }
-    if (localName == 'code' && classes.isEmpty) {
+    if (localName == 'code' && className.isEmpty) {
       return InlineCodeNode(nodes: nodes(), debugHtmlNode: debugHtmlNode);
     }
 
     if (localName == 'a'
-        && (classes.isEmpty
-            || (classes.length == 1
-                && (classes.contains('stream-topic')
-                    || classes.contains('stream'))))) {
+        && (className.isEmpty
+            || (className == 'stream-topic' || className == 'stream'))) {
       final href = element.attributes['href'];
       if (href == null) return unimplemented();
       final link = LinkNode(nodes: nodes(), url: href, debugHtmlNode: debugHtmlNode);
@@ -683,10 +686,7 @@ class _ZulipContentParser {
     }
 
     if (localName == 'span'
-        && (classes.contains('user-mention')
-            || classes.contains('user-group-mention'))
-        && (classes.length == 1
-            || (classes.length == 2 && classes.contains('silent')))) {
+        && _userMentionClassNameRegexp.hasMatch(className)) {
       // TODO assert UserMentionNode can't contain LinkNode;
       //   either a debug-mode check, or perhaps we can make expectations much
       //   tighter on a UserMentionNode's contents overall.
@@ -694,22 +694,15 @@ class _ZulipContentParser {
     }
 
     if (localName == 'span'
-        && classes.length == 2
-        && classes.contains('emoji')
-        && classes.every(_emojiClassRegexp.hasMatch)) {
-      final emojiCode = classes
-        .firstWhere((className) => className.startsWith('emoji-'))
-        .replaceFirst('emoji-', '');
-      assert(emojiCode.isNotEmpty);
-
+        && _emojiClassNameRegexp.hasMatch(className)) {
+      final emojiCode = _emojiCodeFromClassNameRegexp.firstMatch(className)!
+        .group(1)!;
       final unicode = tryParseEmojiCodeToUnicode(emojiCode);
       if (unicode == null) return unimplemented();
       return UnicodeEmojiNode(emojiUnicode: unicode, debugHtmlNode: debugHtmlNode);
     }
 
-    if (localName == 'img'
-        && classes.contains('emoji')
-        && classes.length == 1) {
+    if (localName == 'img' && className == 'emoji') {
       final alt = element.attributes['alt'];
       if (alt == null) return unimplemented();
       final src = element.attributes['src'];
@@ -717,9 +710,7 @@ class _ZulipContentParser {
       return ImageEmojiNode(src: src, alt: alt, debugHtmlNode: debugHtmlNode);
     }
 
-    if (localName == 'span'
-        && classes.length == 1
-        && classes.contains('katex')) {
+    if (localName == 'span' && className == 'katex') {
       final texSource = parseMath(element, block: false);
       if (texSource == null) return unimplemented();
       return MathInlineNode(texSource: texSource, debugHtmlNode: debugHtmlNode);
@@ -756,13 +747,13 @@ class _ZulipContentParser {
       case 'ul': listStyle = ListStyle.unordered; break;
     }
     assert(listStyle != null);
-    assert(element.classes.isEmpty);
+    assert(element.className.isEmpty);
 
     final debugHtmlNode = kDebugMode ? element : null;
     final List<List<BlockContentNode>> items = [];
     for (final item in element.nodes) {
       if (item is dom.Text && item.text == '\n') continue;
-      if (item is! dom.Element || item.localName != 'li' || item.classes.isNotEmpty) {
+      if (item is! dom.Element || item.localName != 'li' || item.className.isNotEmpty) {
         items.add([UnimplementedBlockContentNode(htmlNode: item)]);
       }
       items.add(parseImplicitParagraphBlockContentList(item.nodes));
@@ -775,8 +766,7 @@ class _ZulipContentParser {
     assert(_debugParserContext == _ParserContext.block);
     final mainElement = () {
       assert(divElement.localName == 'div'
-          && divElement.classes.length == 1
-          && divElement.classes.contains("codehilite"));
+          && divElement.className == "codehilite");
 
       if (divElement.nodes.length != 1) return null;
       final child = divElement.nodes[0];
@@ -819,9 +809,8 @@ class _ZulipContentParser {
           }
           span = CodeBlockSpanNode(text: text, type: CodeBlockSpanType.text);
 
-        case dom.Element(localName: 'span', :final text, :final classes)
-            when classes.length == 1:
-          final CodeBlockSpanType type = codeBlockSpanTypeFromClassName(classes.first);
+        case dom.Element(localName: 'span', :final text, :final className):
+          final CodeBlockSpanType type = codeBlockSpanTypeFromClassName(className);
           switch (type) {
             case CodeBlockSpanType.unknown:
               // TODO(#194): Show these as un-syntax-highlighted code, in production.
@@ -848,20 +837,19 @@ class _ZulipContentParser {
     assert(_debugParserContext == _ParserContext.block);
     final imgElement = () {
       assert(divElement.localName == 'div'
-          && divElement.classes.length == 1
-          && divElement.classes.contains('message_inline_image'));
+          && divElement.className == 'message_inline_image');
 
       if (divElement.nodes.length != 1) return null;
       final child = divElement.nodes[0];
       if (child is! dom.Element) return null;
       if (child.localName != 'a') return null;
-      if (child.classes.isNotEmpty) return null;
+      if (child.className.isNotEmpty) return null;
 
       if (child.nodes.length != 1) return null;
       final grandchild = child.nodes[0];
       if (grandchild is! dom.Element) return null;
       if (grandchild.localName != 'img') return null;
-      if (grandchild.classes.isNotEmpty) return null;
+      if (grandchild.className.isNotEmpty) return null;
       return grandchild;
     }();
 
@@ -886,18 +874,16 @@ class _ZulipContentParser {
     }
     final element = node;
     final localName = element.localName;
-    final classes = element.classes;
-    List<BlockContentNode> blockNodes() => parseBlockContentList(element.nodes);
+    final className = element.className;
 
-    if (localName == 'br' && classes.isEmpty) {
+    if (localName == 'br' && className.isEmpty) {
       return LineBreakNode(debugHtmlNode: debugHtmlNode);
     }
 
-    if (localName == 'p' && classes.isEmpty) {
+    if (localName == 'p' && className.isEmpty) {
       // Oddly, the way a math block gets encoded in Zulip HTML is inside a <p>.
       if (element.nodes case [dom.Element(localName: 'span') && var child, ...]) {
-        if (child.classes.length == 1
-            && child.classes.contains('katex-display')) {
+        if (child.className == 'katex-display') {
           if (element.nodes case [_]
                               || [_, dom.Element(localName: 'br'),
                                      dom.Text(text: "\n")]) {
@@ -927,7 +913,7 @@ class _ZulipContentParser {
       case 'h5': headingLevel = HeadingLevel.h5; break;
       case 'h6': headingLevel = HeadingLevel.h6; break;
     }
-    if (headingLevel != null && classes.isEmpty) {
+    if (headingLevel != null && className.isEmpty) {
       final parsed = parseBlockInline(element.nodes);
       return HeadingNode(debugHtmlNode: debugHtmlNode,
         level: headingLevel,
@@ -935,21 +921,20 @@ class _ZulipContentParser {
         nodes: parsed.nodes);
     }
 
-    if ((localName == 'ol' || localName == 'ul') && classes.isEmpty) {
+    if ((localName == 'ol' || localName == 'ul') && className.isEmpty) {
       return parseListNode(element);
     }
 
-    if (localName == 'blockquote' && classes.isEmpty) {
-      return QuotationNode(blockNodes(), debugHtmlNode: debugHtmlNode);
+    if (localName == 'blockquote' && className.isEmpty) {
+      return QuotationNode(debugHtmlNode: debugHtmlNode,
+        parseBlockContentList(element.nodes));
     }
 
-    if (localName == 'div'
-        && classes.length == 1 && classes.contains('codehilite')) {
+    if (localName == 'div' && className == 'codehilite') {
       return parseCodeBlock(element);
     }
 
-    if (localName == 'div'
-        && classes.length == 1 && classes.contains('message_inline_image')) {
+    if (localName == 'div' && className == 'message_inline_image') {
       return parseImageNode(element);
     }
 
diff --git a/test/model/content_test.dart b/test/model/content_test.dart
index 87c6c182e6..dc97c89b92 100644
--- a/test/model/content_test.dart
+++ b/test/model/content_test.dart
@@ -138,7 +138,27 @@ void main() {
       '<p><span class="user-mention silent" data-user-id="2187">Greg Price</span></p>',
       const UserMentionNode(nodes: [TextNode('Greg Price')]));
 
-    // TODO test group mentions and wildcard mentions
+    testParseInline('silent user @-mention, class order reversed',
+      // "@_**Greg Price**" (hypothetical server variation)
+      '<p><span class="silent user-mention" data-user-id="2187">Greg Price</span></p>',
+      const UserMentionNode(nodes: [TextNode('Greg Price')]));
+
+    testParseInline('plain group @-mention',
+      // "@*test-empty*"
+      '<p><span class="user-group-mention" data-user-group-id="186">@test-empty</span></p>',
+      const UserMentionNode(nodes: [TextNode('@test-empty')]));
+
+    testParseInline('silent group @-mention',
+      // "@_*test-empty*"
+      '<p><span class="user-group-mention silent" data-user-group-id="186">test-empty</span></p>',
+      const UserMentionNode(nodes: [TextNode('test-empty')]));
+
+    testParseInline('silent group @-mention, class order reversed',
+      // "@_*test-empty*" (hypothetical server variation)
+      '<p><span class="silent user-group-mention" data-user-group-id="186">test-empty</span></p>',
+      const UserMentionNode(nodes: [TextNode('test-empty')]));
+
+    // TODO test wildcard mentions
   });
 
   testParseInline('parse Unicode emoji, encoded in span element',
@@ -146,6 +166,11 @@ void main() {
     '<p><span aria-label="thumbs up" class="emoji emoji-1f44d" role="img" title="thumbs up">:thumbs_up:</span></p>',
     const UnicodeEmojiNode(emojiUnicode: '\u{1f44d}')); // "👍"
 
+  testParseInline('parse Unicode emoji, encoded in span element, class order reversed',
+    // ":thumbs_up:" (hypothetical server variation)
+    '<p><span aria-label="thumbs up" class="emoji-1f44d emoji" role="img" title="thumbs up">:thumbs_up:</span></p>',
+    const UnicodeEmojiNode(emojiUnicode: '\u{1f44d}')); // "👍"
+
   testParseInline('parse Unicode emoji, encoded in span element, multiple codepoints',
     // ":transgender_flag:"
     '<p><span aria-label="transgender flag" class="emoji emoji-1f3f3-fe0f-200d-26a7-fe0f" role="img" title="transgender flag">:transgender_flag:</span></p>',