How is the padding of display:table-cell determined

I'm trying to come out with a table-like layout, with medicine names appearing on the left and the data occupy the rest of the table. Simply put:

           +-------------+------------+
medicine 1 |  some data  | some data  |
           +-------------+------------+
medicine 2 |  some data  | some data  |
           +-------------+------------+

Since I want to keep the data grid dynamic, I use two <div>'s with the style display:table-cell as two containers, the left one for all the medicine names, and the right one for the data grid. There are several inner <div>'s inside these two table-cell <div>'s, but I'm not sure why the left one has a big padding area on the top when I use Chrome inspect interface to investigate it (please see the image below):

I'm not quite sure which part went wrong, and the inspect interface didn't give me information that seems relevant. I want to learn how to approach this situation. Here is the html code for your reference:

<div style="display:table">
  <div style="display:table-row">
    <div style="display:table-cell">
      <div style="height:85px; width:170px; text-align:right; font-size:13px; margin-right:5px">
        Dexedrine Spansules (Dextroamphetamine, ER) <br/><span style="font-style:italic">(20mg)</span>
      </div>
      <div style="height:85px; width:170px; text-align:right; font-size:13px; margin-right:5px">
        Methamphetamine (Desoxyn, IR) <br/><span style="font-style:italic">(15mg)</span>
      </div>
    </div>
    <div style="display:table-cell; overflow:hidden; max-width:800px">
      <div id="medicine_table_container_2" class="medicine-table-container" style="position:relative; left:0">
        <div style="white-space:nowrap; font-size:0px">
          <div style="display:inline-block; background-color:yellow; width:130px; height:85px; border:1px solid #999; font-size: 12px; white-space:normal">
            <div>
              <div style="display:inline-block; width:70px; height:45px">
                Morning<br/>-
              </div>
              <div style="display:inline-block; width:50px; height:45px">
                Noon<br/>5mg
              </div>
            </div>
            <div>
              <div style="display:inline-block; width:70px; height:35px">
                Afternoon<br/>12mg
              </div>
              <div style="display:inline-block; width:50px; height:35px">
                Evening<br/>-
              </div>
            </div>
          </div>
        </div>
        <div style="white-space:nowrap; font-size:0px">
          <div style="display:inline-block; background-color:yellow; width:130px; height:85px; border:1px solid #999; font-size: 12px; white-space:normal">
            <div>
              <div style="display:inline-block; width:70px; height:45px">
                Morning<br/>-
              </div>
              <div style="display:inline-block; width:50px; height:45px">
                Noon<br/>5mg
              </div>
            </div>
            <div>
              <div style="display:inline-block; width:70px; height:35px">
                Afternoon<br/>12mg
              </div>
              <div style="display:inline-block; width:50px; height:35px">
                Evening<br/>-
              </div>
            </div>
          </div>
        </div>
      </div>
    </div>
  </div>
</div>

Solution

This is about vertical alignment. The default one is set to baseline and produce this output. Simply change the alignment to top on the table-cell and you won't have this issue:

<div style="display:table">
  <div style="display:table-row">
    <div style="display:table-cell;
    vertical-align: top;">
      <div style="height:85px; width:170px; text-align:right; font-size:13px; margin-right:5px">
        Dexedrine Spansules (Dextroamphetamine, ER) <br/><span style="font-style:italic">(20mg)</span>
      </div>
      <div style="height:85px; width:170px; text-align:right; font-size:13px; margin-right:5px">
        Methamphetamine (Desoxyn, IR) <br/><span style="font-style:italic">(15mg)</span>
      </div>
    </div>
    <div style="display:table-cell;
    vertical-align: top; overflow:hidden; max-width:800px">
      <div id="medicine_table_container_2" class="medicine-table-container" style="position:relative; left:0">
        <div style="white-space:nowrap; font-size:0px">
          <div style="display:inline-block; background-color:yellow; width:130px; height:85px; border:1px solid #999; font-size: 12px; white-space:normal">
            <div>
              <div style="display:inline-block; width:70px; height:45px">
                Morning<br/>-
              </div>
              <div style="display:inline-block; width:50px; height:45px">
                Noon<br/>5mg
              </div>
            </div>
            <div>
              <div style="display:inline-block; width:70px; height:35px">
                Afternoon<br/>12mg
              </div>
              <div style="display:inline-block; width:50px; height:35px">
                Evening<br/>-
              </div>
            </div>
          </div>
        </div>
        <div style="white-space:nowrap; font-size:0px">
          <div style="display:inline-block; background-color:yellow; width:130px; height:85px; border:1px solid #999; font-size: 12px; white-space:normal">
            <div>
              <div style="display:inline-block; width:70px; height:45px">
                Morning<br/>-
              </div>
              <div style="display:inline-block; width:50px; height:45px">
                Noon<br/>5mg
              </div>
            </div>
            <div>
              <div style="display:inline-block; width:70px; height:35px">
                Afternoon<br/>12mg
              </div>
              <div style="display:inline-block; width:50px; height:35px">
                Evening<br/>-
              </div>
            </div>
          </div>
        </div>
      </div>
    </div>
  </div>
</div>

Since your code is a bit complex, here is a basic one to reproduce the issue and better understand what's happening:

.table {
  display: table;
  border: 1px solid;
  margin: 5px;
}

.table>div {
  display: table-row;
}

.table>div>span {
  display: table-cell;
  padding: 0 5px;
}

.table>div>span span {
  display: inline-block;
}

baseline
<div class="table">
  <div>
    <span>one line</span>
    <span><span>two <br> line (inline-block)</span></span>
  </div>
</div>
baseline
<div class="table">
  <div>
    <span>two<br> line</span>
    <span><span>two <br> line (inline-block)</span></span>
  </div>
</div>
baseline (with overflow:hidden)
<div class="table">
  <div>
    <span>one line</span>
    <span><span style="overflow:hidden;">two <br> line</span></span>
  </div>
</div>
baseline (with overflow:hidden)
<div class="table">
  <div>
    <span>one line</span>
    <span><span style="overflow:hidden;">another line</span></span>
  </div>
</div>
top will fix all the cases
<div class="table">
  <div>
    <span style="vertical-align:top;">one line</span>
    <span><span>two <br> line</span></span>
  </div>
</div>
<div class="table">
  <div>
    <span style="vertical-align:top;">one line</span>
    <span><span style="overflow:hidden;">two <br> line</span></span>
  </div>
</div>
<div class="table">
  <div>
    <span style="vertical-align:top;">one line</span>
    <span><span style="overflow:hidden;">another line</span></span>
  </div>
</div>
<div class="table">
  <div>
    <span style="vertical-align:top;">two<br> line</span>
    <span><span>two <br> line (inline-block)</span></span>
  </div>
</div>

You can clearly see how the use of inline-block (and overflow:hidden) is the culprit here as it make the calculation of the baseline counter intuitive and unexpected.