<!DOCTYPE html>
<html>
<head>
<style>
input {
border: 3px solid black;
padding: 4px;
width: 300px;
min-height: 100px;
box-sizing: content-box;
/* hide the spin buttons: */
-moz-appearance: textfield;
}
* > input[type=number] {
/* get rid of background gradient for Firefox OS */
background-color: transparent ! important;
}
</style>
</head>
<body>
<input type="number">
</body>
</html>