manifest.json contents:

{
"name": "New Tumblr Nopad",
"version": "0.1",
"manifest_version": 2,
"description": "This extension changes",
"content_scripts": [
{
"matches": ["qhttps://www.tumblr.com/*"],
"css": ["style.css"]
}
]
}


style.css contents:

.tab_notice {
background:#DB6348 !important;
}
.tab_notice_value {
color:#FFFFFF !important;
}