userContent.css For Firefox about:newtab

/*
This CSS is meant for the about:newtab display that was before firefox 57.

In firefox url bar :
about:config
browser.newtabpage.activity-stream.enabled > false

Open Firefox and press ALT to show the top menu, then click on Help → Troubleshooting Information
Click the Show Folder button beside the Profile Folder entry
Create a folder named "Chrome" in the directory that opens
In the chrome folder create a css file with the name userContent.css
Copy the following code to userContent.css
(explanation from superuser.com by Rauf)
*/

@-moz-document url("about:newtab") {

    /* Background */
    body {
        background-color: #232323 !important;
    }

    /* Title */
    .newtab-title {
        background-color: #393939 !important;
        color: rgba(255, 255, 255, 0.8) !important;
        border: 1px solid #232323 !important;
    }

    /* Site block */
    .newtab-site {
        box-shadow: 0 2px 4px #050505 !important;
    }

    /* Search icon */
    #newtab-search-icon {
        background-color: #353535 !important;
    }

    /* Search field */
    #newtab-search-text {
        background-color: #474747 !important;
        color: #dedede !important;
    }

    /* Preferences button */
    #newtab-customize-button {
        fill: rgba(149, 149, 149, 0.6) !important;
    }

    /* Firefox button */
    /* Background */
    #onboarding-overlay {
        background: rgba(27, 27, 27, 0.9) !important;
    }
    /* Window background */
    #onboarding-overlay.onboarding-opened > #onboarding-overlay-dialog {
        background: #2c2c2c !important;
    }
    /* Text color */
    #onboarding-overlay.onboarding-opened > #onboarding-overlay-dialog {
        color: #cecece !important;
    }
}