style.css

body{
    background-color: #fafafa;
}


.dino {
    background-image: url(img/dino.png);
    position: absolute;
    width: 60px;
    height: 60px; 
    bottom: 0;
}

.cacto {
    background-image: url(img/cactus.png);
    position: absolute;
    width: 60px;
    height: 60px;
    bottom: 0;
}

.game-over {
    text-align: center;
    color: #666;
    margin: 50px 0;
    font-family: arial;
}

@keyframes slideright {
    from {
        background-position: 70000%;
    }
    to {
        background-position: 0%;
    }
}

.bg {
    position: absolute;
    bottom: 0px;
    background-image: url('img/background.png');
    background-repeat: repeat-x;
    animation: slideright 1300s infinite linear;
    -webkit-animation: slideright 1300s infinite linear;
    width: 100%;
    height: 200px;
}

.button {
    background-color: aqua;
    color: white;
    padding: 10px 50px;
    cursor: pointer;
    width: 125px;
    display: block;
    margin-left: auto;
    margin-right: auto;
}