Take a look in your css around line 329 and remove the width: 100%;
and that should fix it.
input,
select,
textarea {
background: #fff;
border: 1px solid #ddd;
border-radius: 3px;
box-shadow: 1px 1px 3px #eee inset;
color: #999;
font-family: 'Helvetica Neue', Helvetica, Arial, sans-serif;
font-size: 16px;
font-size: 1rem;
padding: 12px;
padding: 0.75rem;
width: 100%; <---- Remove
}