CSS desativado div
.disabledbutton {
pointer-events: none;
opacity: 0.4;
}
Lonely Loris
.disabledbutton {
pointer-events: none;
opacity: 0.4;
}<input type="text" name="username" value="admin" >
<style type="text/css">
input[name=username] {
pointer-events: none;
}
</style>