Configurable List: How can I format the widget's layout?

 - The font inside the Configurable list widget is larger than the rest of the form - how can I get it to match the other fields?

 - The 'Age group' and 'Sex' columns in the Configurable list widget are too close to the previous column - can that be adjusted?

Yes, it's possible to achieve that, you will only need to inject the following code: 

- This will affect the font size, you may change the value: 

table#list {

    font-size: 12px;

}

- This will separate the desired columns: 

.col2, .col4{

    padding-left: 15px;

}

This guide will help you injecting the code to your widget: https://www.jotform.com/help/428-How-to-Inject-CSS-Codes-to-Widgets 

I hope this helps.