style.css

* {
    padding: 0;
    margin: 0;
    box-sizing: border-box;
}

body {
    background-color: #d8e6e9;
}

.game {
    width: 600px;
    height: 200px;
    border: 1px solid #000000;
    margin: auto;
    align-items: center;
    justify-content: center;
    /* display: flex; */
    position: relative;
}

#dino {
    width: 70px;
    height: 70px;
    background-image: url(t-rex.png);
    background-size: auto 70px;

    position: relative;
    top: 143px;
}

.jump {
    animation: jump 0.3s linear;
}

@keyframes jump {
    0% {
        top: 143px;
       
    }

    30% {
        top: 115px;
    }

    50% {
        top: 70px;
    }

    80% {
        top: 115px;
    }

    100% {
        top: 143px;
    }
}


#cactus {
    width: 20px;
    height: 40px;
    position: relative;
    top: 91px;
    left: 580px;
    

    background-image: url(cactus.png);
    background-size: 20px 40px;
    animation: cactus-block 1.2s infinite linear;
}

@keyframes cactus-block {
    0% {
        left: 600px;
    }

    100% {
        left: -20px;
    }
}