Targeting specific elements with CSS only
Markup

If you have a td that you're giving a class that indicates that it is some sort of heading, you should be using a th instead.  The th element is allowed to appear in a tbody, it isn't restricted to thead.

When validated, this table will generate warnings regarding different numbers of cells in each row.  The correct structure should look like this:

&lt;table class="greyBG"&gt;
    &lt;tbody&gt;
        &lt;tr&gt;
            &lt;th rowspan="4"&gt;Landscape&lt;/th&gt;
            &lt;td&gt;Lorum Ipsum&lt;/td&gt;
        &lt;/tr&gt;
        &lt;tr&gt;
            &lt;td&gt;Lorum Ipsum&lt;/td&gt;
        &lt;/tr&gt;
        &lt;tr&gt;
            &lt;td&gt;Lorum Ipsum&lt;/td&gt;
        &lt;/tr&gt;
        &lt;tr&gt;
            &lt;td&gt;Lorum Ipsum&lt;/td&gt;
        &lt;/tr&gt;
    &lt;/tbody&gt;
&lt;/table&gt;


Be consistent with your indentation.

CSS

Now that the markup is simplified, it's child's play to simplify the CSS

.greyBG td {
    width: 100%;
    text-align: center;
}


Demo:  http://codepen.io/cimmanon/pen/GqKcx