at least for me, this is the corrct version of your code:
ul li {
list-style-type:"• ";
}
ul ul li {
list-style-type:"◦ ";
}
ul ul ul li {
list-style-type:"▪ ";
}
ul ul ul ul li {
list-style:"▫ ";
}
ul ul ul ul ul li {
list-style:"▴ ";
}
ul ul ul ul ul ul li {
list-style:"▵ ";
}