selection.style(name[, value[, priority]])
If a value is specified, sets the style property with the specified name to the specified value on the selected elements and returns this selection. If the value is a constant, then all elements are given the same style property value; otherwise, if the value is a function, then the function is evaluated for each selected element, in order, being passed the current datum (d), the current index (i), and the current group (nodes), with this as the cur