diff --git a/python_docs_theme/static/pydoctheme.css b/python_docs_theme/static/pydoctheme.css
index 8c0ddfc..a83030a 100644
--- a/python_docs_theme/static/pydoctheme.css
+++ b/python_docs_theme/static/pydoctheme.css
@@ -444,6 +444,26 @@ div.footer a:hover {
     color: #229;
 }
 
+/* C API thread safety annotations */
+:root {
+    --threadsafety-incompatible: var(--bad-color);
+    --threadsafety-compatible: var(--middle-color);
+    --threadsafety-safe: var(--good-color);
+}
+
+.threadsafety.threadsafety-incompatible {
+    color: var(--threadsafety-incompatible);
+}
+
+.threadsafety.threadsafety-compatible {
+    color: var(--threadsafety-compatible);
+}
+
+.threadsafety.threadsafety-safe {
+    color: var(--threadsafety-safe);
+}
+
+
 dl > dt span ~ em,
 .sig {
     font-family: Menlo, Consolas, Monaco, Liberation Mono, Lucida Console, monospace;