Align text in a table header

Try:

text-align: center;

You may be familiar with the HTML align attribute (which has been discontinued as of HTML 5). The align attribute could be used with tags such as

<table>, <td>, and <img> 

to specify the alignment of these elements. This attribute allowed you to align elements horizontally. HTML also has/had a valign attribute for aligning elements vertically. This has also been discontinued from HTML5.

These attributes were discontinued in favor of using CSS to set the alignment of HTML elements.

There isn't actually a CSS align or CSS valign property. Instead, CSS has the text-align which applies to inline content of block-level elements, and vertical-align property which applies to inline level and table cells.

Try to use text-align in style attribute to align center.

<th class="not_mapped_style" style="text-align:center">DisplayName</th>

Try using style for th

th {text-align:center}