body {
    font-family: Arial, Helvetica, sans-serif;
    text-align: center;
}

.tanks img{
    height: 75px;
    width: 120px;
    margin: 1px;
}

.tanks_checked img{
    /* filter: brightness(30%); */
    background-color: gray;
}

.button {
    width: 100px;
    height: 50px;
    font-size: 20px;
}