How to overlap a child element of one div with`display:table-cell` over another div with `display:table-cell?`

Question

JSFiddle

In this SSCCE, there is a .wrapper div with display:table; set, and it has three cell divs with display:table-cell.

The .outer-number-container is a child of the .left-cell div, but I want it to appear over the .middle-cell such that a vertical line passing through it's center would exactly be on the .middle-cell; I mean half of it should be appearing/displayed in the .left-cell and the other half in the .right-cell.

I have tried to do this with a negative-margin on .right-cell but that doesn't seem to work. So how should I achieve this?

HTML:

        <div class="left-cell cell" align="left">
            <div class="step-container">
                <div class="content-box">
                        <div class="content-image" style="background-image: url(http://simeonhookphotography.com/wp-content/gallery/favorites/norway-countryside-to-bergen.jpg);"></div>
                        <div class="content-text">Lorem Ipsum is simply dummy text of the printing and typesetting industry. Lorem Ipsum has been the industry's standard dummy text ever since the 1500s, when an unknown printer took a galley of type and scrambled it to make a type specimen book. It has survived not only five centuries, but also the leap into electronic typesetting, remaining essentially unchanged. It was popularised in the 1960s with the release of Letraset sheets containing Lorem Ipsum passages, and more recently with desktop publishing software like Aldus PageMaker including versions of Lorem Ipsum.</div>
                    </div>


                <div class="notch-outer-container">
                    <div class="notch-inner-container">
                        <div class="right-face-notch notch"></div>
                    </div>
                </div>


                <div class="number-outer-container">
                    <div class="number-inner-container">
                        <div class="number-banner"></div>
                    </div>
                </div>
            </div>
        </div>




        <div class="middle-cell cell"></div>




        <div class="right-cell cell" align="right" >
            <div class="step-container">
                <div class="number-outer-container">
                    <div class="number-inner-container">
                        <div class="number-banner"></div>
                    </div>
                </div>

                <div class="notch-outer-container">
                    <div class="notch-inner-container">
                        <div class="left-face-notch notch"></div>
                    </div>
                </div>

                <div class="content-box">
                    <div class="content-text">Lorem Ipsum is simply dummy text of the printing and typesetting industry. Lorem Ipsum has been the industry's standard dummy text ever since the 1500s, when an unknown printer took a galley of type and scrambled it to make a type specimen book. It has survived not only five centuries, but also the leap into electronic typesetting, remaining essentially unchanged. It was popularised in the 1960s with the release of Letraset sheets containing Lorem Ipsum passages, and more recently with desktop publishing software like Aldus PageMaker including versions of Lorem Ipsum.</div>
                    <div class="content-image" style="background-image:url(http://www.penttila-gardens.com/activities/walking/countryside/images/02-harvest.jpg)">
                    </div>
                </div>

            </div>
         </div>


    </div>

CSS:

.wrapper {
    height:100%;
    width: 95%;
    margin: 10px auto;
    display: table;
    background-color:teal;
}

.cell {
    display:table-cell;
    vertical-align: top;
}

.left-cell {
    width:50%
}

.middle-cell {
    height:100%;
    background-color: white;
    width:1.5px;
    font-size: 0;
    box-shadow: 0px 50px 10px black;
    -moz-box-shadow: 0px 50px 10px black;
    -webkit-box-shadow: 0px 50px 10px black;
}

.right-cell {
   /* width:50%*/ /*Commenting b/c both right and left 50, 50 squish and vanish the middle between them*/
    background-color: blueviolet
}



.step-container {
    max-height: 200px;
    font-size: 0;
}



.content-box {
    display: inline-block;
    width: 250px;
    height: 200px;
    /*border: 5px solid blue;*/
    font-size: 0;
}

.content-box .content-image {
    width:35%;
    height:100%;
    background-size: cover;
    display: inline-block
}

.content-box .content-text {
    background-color: rgb(255, 255, 255);  
    color: #1c1a1a;
    font-family: sans-serif;
    font-size: 15px;
    font-weight: 100;
    overflow:auto;
    display: inline-block;
    width:65%;
    height:100%;
}

.notch-outer-container {
    display:inline-block;
}

.left-cell .notch-outer-container {
    margin-right: 10px;
}

.right-cell .notch-outer-container {
    margin-left: 10px;
}

.notch-inner-container {
    height:200px;
    display:flex;
    flex-direction: column;
    justify-content: center;
}

.notch {
    width: 0; 
    height: 0; 
    border-top: 15px solid transparent;
    border-bottom: 15px solid transparent;
}

.right-face-notch {
    border-left: 15px solid brown;
}

.left-face-notch {
    border-right: 15px solid brown;
}

.number-outer-container {
    display:inline-block;
}

.number-inner-container {
    height:200px;
    display:flex;
    flex-direction: column;
    justify-content: center;
}

.number-banner {
    width:30px;
    height:30px;
    background-color:crimson;
    -moz-border-radius: 15px; 
    -webkit-border-radius: 15px; 
    border-radius: 15px;
}

.right-cell .number-outer-container {
    display: none;
}

Answer 1

In your case i manage this point with position absolute:

.number-inner-container {
    position:relative;
}

.number-banner {
    position:absolute;
    left:-13px;
    top:50%;
    margin-top:-15px;
}