Custom Extension not adding css

[marcview]

if i add css thru a module it does not work, the js is working but not the css

{
"scriptList": [
"__APPEND__",
"client/modules/editor/lib/editor.js"
],
"developerModeScriptList": [
"__APPEND__",
"client/modules/editor/lib/editor.js"
],
"cssList": [
"__APPEND__",
"client/modules/editor/lib/css/my-own-stylessss.css"
],
"developerModeCssList": [
"__APPEND__",
"client/modules/editor/lib/css/my-own-stylessss.css"
]
}