With over a million active installs, Contact Form 7 is by far one of the most popular WordPress plugins ever. It’s popularity probably has a lot to do with the truth behind its description: “Simple but flexible.”
Contact Form 7 allows you to create multiple contact forms using nothing but simple HTML markup (which it generates for you). Once created, each form can be quickly deployed by placing its corresponding shortcode where you’d like the form to appear; in page, post, or widget area. Messages submitted via the forms are sent to the email address provided in the plugin settings and spam is combatted via support for CAPTCHA and Akismet.
Contact Form 7 is so simple that it seems literally anyone can use it effectively. Styling too, is intended to be simple. But perhaps too simple for some. By default the Contact Form 7 plugin does not style its forms. Any styling they do have is a result of default stylings present in a WordPress theme’s style sheet.
So how to customize the style of Contact Form 7 you can read in this article.