Still have light theme as alternative.

app/static/css/screen-light.css

@@ -0,0 +1,42 @@
+/**
+ * Copyright 2020 Google LLC
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+body            { font-family: sans-serif; background: #eee; }
+a, h1, h2       { color: #377ba8; }
+h1, h2          { font-family: 'Georgia', serif; margin: 0; }
+h1              { border-bottom: 2px solid #eee; }
+h2              { font-size: 1.2em; }
+
+.page           { margin: 2em auto; width: 35em; border: 5px solid #ccc;
+                  padding: 0.8em; background: white; }
+.entries        { list-style: none; margin: 0; padding: 0; }
+.entries li     { margin: 0.8em 1.2em; }
+.entries li h2  { margin-left: -1em; }
+.add-entry      { font-size: 0.9em; border-bottom: 1px solid #ccc; }
+.add-entry dl   { font-weight: bold; }
+.metanav        { text-align: right; font-size: 0.8em; padding: 0.3em;
+                  margin-bottom: 1em; background: #fafafa; }
+.flash          { background: #cee5F5; padding: 0.5em;
+                  border: 1px solid #aacbe2; }
+.error          { background: #f0d6d6; padding: 0.5em; }
+
+.wikilink:before {
+	content: "[["
+}
+
+.wikilink:after {
+	content: "]]"
+}