It seems that the current way to change the background-color of an input that is autofilled (username is my example bellow) by the browser is by using a transition:
input:-webkit-autofill,
input:-webkit-autofill:hover,
input:-webkit-autofill:focus,
input:-webkit-autofill:active {
    transition: background-color 5000s ease-in-out 0s;
    -webkit-text-fill-color: #fff !important;
}
#input-container input{
    display: block;
    background-color: transparent;
}
This is working but is there any cleaner way to do it whiteout having to create a transition?

 
    