#train{
    display: flex;
    gap: 1vw;
}
.car{
    width: 10vw;
    height:10vw;
    background-color: aquamarine;
    position: relative;
    text-align: center;
}
.car:before{
    content: " ";
    width: 3vw;
    height: 3vw;
    display: block;
    position:absolute;
    top: 8.5vw;
    background-color: blueviolet;
}
.car:after{
    content: " ";
    width: 3vw;
    height: 3vw;
    display: block;
    position:absolute;
    left: 7vw;
    top: 8.5vw;
    background-color: blueviolet;
}