Just in case anyone wants to hide ALL the buttons from non-staff users, here is my code:
body:not(.staff) .d-editor-button-bar {
/* Hide specific buttons */
button {
/* Inline buttons */
&.align_justify_button,
&.align_right_button,
&.align_center_button,
&.subscript_button,
&.superscript_button,
&.strikethrough_button,
&.underline_button
{
display: none;
}
/* Popup menu */
&.toolbar-popup-menu-options {
[data-name="Float left"],
/* ... */ {
display: none;
}
}
}
}