diff --git a/delta/html.py b/delta/html.py
index d34fed8..7dd0582 100644
--- a/delta/html.py
+++ b/delta/html.py
@@ -37,9 +37,13 @@ def styled(element, styles):
     if element.tag != 'span':
         element = sub_element(element, 'span')
     declare = parseStyle(element.attrib.get('style', ''))
-    for k, v in styles.items():
-        declare.setProperty(k, v)
-    element.attrib['style'] = declare.getCssText(' ')
+    try:
+        for k, v in styles.items():
+            declare.setProperty(k, v)
+        element.attrib['style'] = declare.getCssText(' ')
+    except:
+        # Ignore invalid css attributes
+        pass
     return element
 
 def classed(element, *classes):
diff --git a/tests/test_html.py b/tests/test_html.py
index 614d05c..e1a69af 100644
--- a/tests/test_html.py
+++ b/tests/test_html.py
@@ -59,6 +59,21 @@ def test_colors():
     source = '<p><span style="background-color: #000; color: #FFF">quill</span></p>'
     assert html.render(ops) == source
 
+def test_unsupported_style_attribute():
+    ops = [
+            {"insert": "quill", "attributes": {"color": "var(--some-color)", "background": "#000000"}}
+    ]
+
+    source = '<p><span style="background-color: #000">quill</span></p>'
+    assert html.render(ops) == source
+
+    ops = [
+        {"insert": "quill", "attributes": {"background": "#000000", "color": "#FFFFFF"}}
+    ]
+
+    source = '<p><span style="background-color: #000; color: #FFF">quill</span></p>'
+    assert html.render(ops) == source
+
 def test_classes():
     ops = [
         {"insert":"Quill", "attributes": {"font": "monospace", "size": "huge"}}