                   <img src="../img/tiles/4-1.png" class="nav-unit-tile-s">
                        <span class="nav-unit-title-s"> Point Estimation </span>
                    </div>
                    <div class="nav-unit-wrapper-s tile2">
                        <img src="../img/tiles/4-2.png" class="nav-unit-tile-s">
                        <span class="nav-unit-title-s"> Confidence Interval </span>
                    </div>
                    <div class="nav-unit-wrapper-s tile3">
                  