How do I 'center' 'Save / Add' button

Also, how do I 'center' 'Save / Add' button. Notice the text is pushed to the right. 

You can add the following CSS styling to your current Configurable list:

#list  span {

  width: 440px;

}

.add {

  padding: 5px;

}

To add the code above, you need to select the list and click on the Widget Settings, and in Custom CSS add the lines at the end. Since you have multiple fields, you need to do this in each field. 

To configure Save / Add button for the Infinitive List, add the following:

.save {

width: 150px;

}

Once again, you need to open the Widget settings, and to add the code in the Custom CSS tab. Please make sure you add it to the end.

If the field is too wide, you can adjust the size to your likings. Currently, it's set to 150px, but you can change that number to suit your needs. 

I hope this will help you.

Perfection! Thank you!