FlexiContact Plus comes with about 20 different CSS files, so you should find something that suits your needs. Then you can choose the button colour, the type of check boxes and radio buttons, the style of error messages, valid field styling, and many other options.
For complex forms you can use "inline" fields that sit side-by side, and enclose groups of fields in field sets with or without frames. You can also add fixed texts, titles, or even your own HTML anywhere in a form.
Switch languages to see each page of this site with a different CSS file and/or various different options.