the 40px just made it stick to the bottom. however, with 1em insted you can change the height of the input and it will always stay in the middle.
@@ -40,7 +40,7 @@ textarea,
.field {
display: block;
height: 40px;
- line-height: 40px;
+ line-height: 1em;
padding: 0 12px;
margin-bottom: 14px;
font-size: 1em;