Use silver for line number background

Author: jeremypw

data/styles/elementary-highcontrast-light.xml

@@ -8,7 +8,7 @@
   <color name="bg-0"    value="#abacae"/> <!-- SILVER700-->
   <color name="bg-1"    value="#d4d4d4"/> <!-- SILVER300-->
   <color name="bg-2"    value="#fafafa"/> <!-- SILVER100-->
-  <color name="bg-3"    value="#f7efe1"/> <!-- 50% LATTE100 + 50% WHITE
+  <color name="bg-3"    value="#EAEAEA"/> <!-- 50% SILVER300 + 50% WHITE
   
    -->