improved CM

Signed-off-by: zhangtianli2006 <49156174+zhangtianli2006@users.noreply.github.com>

Author: ZTL-UwU

src/assets/code_mirror/tomorrow.css

@@ -55,7 +55,7 @@
 }
 
 .CodeMirror-gutters {
-    background: #f9f9f9;
+    background: #fcfcfc;
     border-right: none;
 }