Check out line 378 in your css for the input/forms and remove or comment out the width: 100%;
–
/* Forms
--------------------------------------------- */
input,
select,
textarea {
background: #fff;
border: 1px solid #ddd;
border-radius: 3px;
color: #999;
font-size: 16px;
padding: 6px 12px;
width: 100%;
}