Hi, @judi!
You can assign a class to the radio button in your form template on the settings page. Then open the Contact Form 7's CSS stylesheet file, possibly located at:
/wp-content/plugins/contact-form-7/stylesheet.css
and setup css rules for the input with class "radio":
input.my_radio {
width: 140px;
}
To assign a class to radio input or to checkbox input use:
[radio your-eyes-color class:my_radio "brown" "green" "blue"]
Above code will generate the markup:
<input type="radio" name="your-eyes-color" class="my_radio" value="brown" /> brown
<input type="radio" name="your-eyes-color" class="my_radio" value="green" /> green
<input type="radio" name="your-eyes-color" class="my_radio" value="blue" /> blue
Learn more at Contact Form 7 website.
Good luck!