h1{

    text-align: center;
    margin: 20px 0;

}

.grille {

    width: 500px;
    height: 500px;
    display: flex;
    flex-wrap: wrap;
    border: 1px solid #000;
    box-shadow: 0 2px 10px rgb(0, 0, 0, 0.2);
    margin: 0 auto;
    background: url(ressources/background-black.png);
    animation: background-defile 5s linear infinite;

}

@keyframes background-defile {

    from{

        background-position-y: 0px;

    }
    to{

        background-position-y: 256px;

    }

}


.grille div {

    width: 25px;
    height: 25px;

}

.tireur {

    background: url(ressources/vaisseau.png);
    transform: rotate(180deg);
    background-position: center;
    background-size: contain;

}

.alien {

    background: url(ressources/ennemies.png);
    background-position: center;
    background-size: contain;

}

.boom {

    background-color: red;

}

.laser {

    background-color: orange;

}