copia e incolla queste due regole:
select, textarea, input[type="text"], input[type="password"], input[type="datetime"], input[type="datetime-local"], input[type="date"], input[type="month"], input[type="time"], input[type="week"], input[type="number"], input[type="email"], input[type="url"], input[type="search"], input[type="tel"], input[type="color"], .inputbox {
background: #fff none repeat scroll 0 0;
width: auto;
}
select, textarea, input[type="text"], input[type="password"], input[type="datetime"], input[type="datetime-local"], input[type="date"], input[type="month"], input[type="time"], input[type="week"], input[type="number"], input[type="email"], input[type="url"], input[type="search"], input[type="tel"], input[type="color"], .inputbox {
background-color: #fff;
background-image: none;
border: 1px solid #1f1f1f;
border-radius: 4px;
box-shadow: 0 1px 1px rgba(0, 0, 0, 0.075) inset;
color: #4b4b4b;
display: block;
font-size: 16px;
height: 36px;
line-height: 1.42857;
padding: 6px 12px;
transition: border-color 0.15s ease-in-out 0s, box-shadow 0.15s ease-in-out 0s;
width: 100%;
}
in fondo al file css principale del tuop template o del custom css se ce l'hai. Vediamo se siamo sulla strada giusta ...