If you are comfortable with HTML and CSS and prefer to customize the form yourself, the HTML form may be suitable for you.
These forms are generated differently than hosted or iframe forms. The main difference is that the html form is not saved in your account and will not appear in your list of forms.
After you create it, you will get the full HTML code to paste in the existing code of your website. You can edit it or use it as is. You can always go back and make changes to it later.