        <span class="nav-unit-title-s"> Conditional Probability </span>
                    </div>
                </div>
                <div id="pd">
                    <div class="nav-unit-wrapper-s tile1">
                        <img src="../img/tiles/3-1.png" class="nav-unit-tile-s">
                        <span class="nav-unit-title-s"> Random Variable </span>
                    </div>
                    <div class="nav-unit-wrapper-s tile2">
                        <img src="../img/tiles/3-2.png