After hours of trying to figure this out. I finally got it working by adding the following code, which does a little more than resize the price input field, into my child theme CSS. The plug-in came with it set to 100 percent, which just seems odd.
//form.checkout input.input-text, .woocommerce input.input-text {
width: 20%;
padding: 8px;
height: auto;
border: 2px solid #ff7c00;
-webkit-box-sizing: border-box;
-moz-box-sizing: border-box;
box-sizing: border-box;
-webkit-border-radius: 0;
-moz-border-radius: 0;
border-radius: 0;
margin: 12px;
} //
