diff --git a/cellxgene_gateway/cache_entry.py b/cellxgene_gateway/cache_entry.py
index 60563a1..b032085 100644
--- a/cellxgene_gateway/cache_entry.py
+++ b/cellxgene_gateway/cache_entry.py
@@ -19,6 +19,7 @@ from cellxgene_gateway.cellxgene_exception import CellxgeneException
 from cellxgene_gateway.util import current_time_stamp
 from cellxgene_gateway.flask_util import querystring
 
+
 class CacheEntry:
     def __init__(
         self,
@@ -99,13 +100,20 @@ class CacheEntry:
 
     def rewrite_text_content(self, cellxgene_content):
         # for v0.16.0 compatibility, see issue #24
-        gateway_content = re.sub('(="|\()/static/', f'\\1{self.gateway_basepath()}static/', cellxgene_content).replace(
-            "http://fonts.gstatic.com", "https://fonts.gstatic.com"
-        ).replace(self.cellxgene_basepath(), self.gateway_basepath())
+        gateway_content = (
+            re.sub(
+                '(="|\()/static/',
+                f"\\1{self.gateway_basepath()}static/",
+                cellxgene_content,
+            )
+            .replace("http://fonts.gstatic.com", "https://fonts.gstatic.com")
+            .replace(self.cellxgene_basepath(), self.gateway_basepath())
+        )
         return gateway_content
 
     def gateway_basepath(self):
         return f"{env.external_protocol}://{env.external_host}/view/{self.key.pathpart}/"
+
     def cellxgene_basepath(self):
         return f"http://127.0.0.1:{self.port}"
 
@@ -165,7 +173,9 @@ class CacheEntry:
             )
         content_type = cellxgene_response.headers["content-type"]
         if "text" in content_type:
-            gateway_content = self.rewrite_text_content(cellxgene_response.content.decode())
+            gateway_content = self.rewrite_text_content(
+                cellxgene_response.content.decode()
+            )
         else:
             gateway_content = cellxgene_response.content
 
diff --git a/tests/test_cache_entry.py b/tests/test_cache_entry.py
index c5ec12e..31a702e 100644
--- a/tests/test_cache_entry.py
+++ b/tests/test_cache_entry.py
@@ -2,15 +2,22 @@ import unittest
 from cellxgene_gateway.cache_entry import CacheEntry
 from cellxgene_gateway.cache_key import CacheKey
 
-key = CacheKey('czi/pbmc3k.h5ad', 'pbmc3k.h5ad', 'tmp.csv')
+key = CacheKey("czi/pbmc3k.h5ad", "pbmc3k.h5ad", "tmp.csv")
+
 
 class TestRenderEntry(unittest.TestCase):
     def test_GIVEN_absolute_static_url_THEN_include_path(self):
-        actual = CacheEntry.for_key(key, 8000).rewrite_text_content("src:url(/static/assets/")
-        expected = "src:url(http://localhost:5005/view/czi/pbmc3k.h5ad/static/assets/"
-        self.assertEqual(actual, expected)
-    def test_GIVEN_absolute_src_THEN_include_path(self):
-        actual = CacheEntry.for_key(key, 8000).rewrite_text_content('<link rel="shortcut icon" href="/static/assets/favicon.ico">')
-        expected = '<link rel="shortcut icon" href="http://localhost:5005/view/czi/pbmc3k.h5ad/static/assets/favicon.ico">'
+        actual = CacheEntry.for_key(key, 8000).rewrite_text_content(
+            "src:url(/static/assets/"
+        )
+        expected = (
+            "src:url(http://localhost:5005/view/czi/pbmc3k.h5ad/static/assets/"
+        )
         self.assertEqual(actual, expected)
 
+    def test_GIVEN_absolute_src_THEN_include_path(self):
+        actual = CacheEntry.for_key(key, 8000).rewrite_text_content(
+            '<link rel="shortcut icon" href="/static/assets/favicon.ico">'
+        )
+        expected = '<link rel="shortcut icon" href="http://localhost:5005/view/czi/pbmc3k.h5ad/static/assets/favicon.ico">'
+        self.assertEqual(actual, expected)