make bg transparent

cpu-widget/cpu-widget.lua

@@ -14,7 +14,7 @@ local wibox = require("wibox")
 local cpugraph_widget = wibox.widget {
     max_value = 100,
     color = '#74aeab',
-    background_color = "#1e252c",
+    background_color = "#00000000",
     forced_width = 50,
     step_width = 2,
     step_spacing = 1,
@@ -52,4 +52,4 @@ watch("cat /proc/stat | grep '^cpu '", 1,
     cpugraph_widget
 )
 
-return cpu_widget
+return cpu_widget