Making a payment field hold more characters

I need the payment field on this to be longer in length so users can see more than 5 digits. How can I do that? I have tried looking in the source code but am unable to find anything, maybe css?

Adding the following CSS to your form will allow for adjusting the width of the payment field value input:

#input_5_donation {
    width : 100px;
}

Increase or decrease the value based on how many characters you need to show.