
        #center {
            margin-left: -50px;
            margin-top: -50px;
            left: 50vw;
            top: 50vh;
            background: blue;
        }

        .sentinels {
            position: relative;
            margin-left: 200vw;
            margin-top: 200vh;
            outline: 10px solid yellow;
        }

        a {
            position: fixed;
            display: block;
            background: rgb(173, 173, 173);
            left: 0;
            top: 0;
        }

        a 