How to style (change color) the default 'please select' option?

[stratboy]

Hi, I don't know if this thing depends on your script, or it's just a browaser thing. Anyway I try to ask. The 'please select' option shown, is black. I would need to change it's color, but it seems it doesn't work, even if the style is detected by console. For example:

form select.crs option:first-child {
  color: #dc2020 !important;
}

This is applied, but doesn't show red. I really can't understand why. Could you point me to the right direction?

Attaching an image only to exmplain the reason why I need to chage the color: simply the rest of the form has lighter grey labels.