diff --git a/server-core/src/main/java/io/onedev/server/web/page/simple/simple.css b/server-core/src/main/java/io/onedev/server/web/page/simple/simple.css
index cd8f836c4c..8516e3f0df 100644
--- a/server-core/src/main/java/io/onedev/server/web/page/simple/simple.css
+++ b/server-core/src/main/java/io/onedev/server/web/page/simple/simple.css
@@ -4,6 +4,7 @@
 }
 .SimplePage.dark-mode {
 	background: url(/img/dark-mesh.jpg) no-repeat left top fixed;
+	background-size: cover;
 }
 .SimplePage>body {
 	background: transparent;