One of the versions you posted actually works for all modern browsers (where CSS selectors level 3 are supported):
div ul:not(:first-child) {
background-color: #900;
}
If you need to support legacy browsers, or if you are hindered by the :not
selector's limitation (it only accepts a simple selector as an argument) then you can use another technique:
Define a rule that has greater scope than what you intend and then "revoke" it conditionally, limiting its scope to what you do intend:
div ul {
background-color: #900; /* applies to every ul */
}
div ul:first-child {
background-color: transparent; /* limits the scope of the previous rule */
}
When limiting the scope use the default value for each CSS attribute that you are setting.