QTextEdit {
    background-color: black;
    color: white;            /* sets the main text color */
}

> texworks -stylesheet /pathto/mystyle.css

"C:Program FilesMiKTeX 2.9miktexbinx64miktex-texworks.exe"

"C:Program FilesMiKTeX 2.9miktexbinx64miktex-texworks.exe" -stylesheet C:Usersznhleungblack-background.css