How can I change the color of a rectangle behind the input field?

Please take a look at my form. I would like to change the orange rectangle to red to match the submit button. How can I do this? All I seem to be able to change is the color of the buttons and input fields.

You can inject the custom css code below to change the color of the rectangle to red.

#id_3 {

    background: #cd0909;

}

If you need further assistance, please let us know.