How do adjust alignemnt of ghost text/ defult text to be different then enter value?

My client wants the ghost text to be light grey and centred, while the enter data to the black and left aligned.

I understand how to  enter the default text and change the colour for the two but not alignment.

Here what I have

// On Focus script:

if (event.target.value==event.target.defaultValue) {

    event.target.value = "";

    event.target.textColor = color.black;

    event.target.alignment = 0

}

// On Blur script:

if (event.target.value=="") {

    event.target.value = event.target.defaultValue;

    event.target.textColor = color.ltGray;

    event.target.alignment = 1

}