diff --git a/doc/_themes/sphinx13b/static/sphinx13b.css b/doc/_themes/sphinx13b/static/sphinx13b.css
index bc4609d5..42165f6b 100644
--- a/doc/_themes/sphinx13b/static/sphinx13b.css
+++ b/doc/_themes/sphinx13b/static/sphinx13b.css
@@ -405,7 +405,11 @@ div.attention {
 }
 
 div.caution, div.warning {
-    border: 1px solid #940000;
+    border: 1.5px solid #940000;
+}
+
+div.tip {
+    border: 1.5px solid #009400;
 }
 
 div.admonition > ul,