I posted some styling code in another thread:
/*input fields*/
.wpcf7-form textarea{
width:95%;
padding:10px;
font-size:12px;
font-family: Arial, Helevtica, Verdana, san-serif;
}
.wpcf7-text, .wpcf7-submit, .text_area{
padding:7px;
font-size:12px;
font-family: Arial, Helevtica, Verdana, san-serif;
}
.wpcf7-submit{
padding:7px 12px 6px 12px;
cursor:pointer;
border-style: solid;
border-width: 1px;
}
.wpcf7-text, textarea, select {
background: none repeat scroll 0 0 #F8F8F8;
border: 1px solid #EEEEEE;
}
.wpcf7-submit {
background-image: url("../images/skin-minimal/arrow-right-white.png");
background-position: right center;
background-repeat: no-repeat;
}
Probably it won't style everything perfect but it's a good starting point. I'd add the code to css/custom.css.