.reticle {
    position:absolute;
    border:2px solid red;
    border-bottom:0 none;
    border-right:0 none;
    width: 10px;
    height: 10px;
    z-index: 1000000;
    font-size:10px;
    font-weight:bold;
    color:red;
    line-height:10px;
    padding:5px;
    top:10rem;
    left:10rem;
}
.reticle::before {
    content:'';
    position:absolute;
    border:2px solid red;
    border-top:0 none;
    border-left:0 none;
    width: 10px;
    height: 10px;
    z-index: 1000000;
    transform: translate(calc(-150% + 1px), calc(-150% + 1px));
}

.reticle::after {
    content:'';
    position:absolute;
    border:1px solid red;
    border-radius: 50%;
    width: 10px;
    height: 10px;
    z-index: 1000000;
    transform: translate(-100%, calc(-10px + -100%));
}