First, remove all BR and LABEL tags from the HTML markup.
Next append a closind DIV tag at the end of the markup.
PHP Code
$html = null;
$html .= "<div class=\"dropCenter\">";
$html .= "<select id=\"projectDropDown\" name=\"projectDropDown\">";
$html .= "<option value=\"\"></option>";
while($row = oci_fetch_array($compCuttingResult,OCI_ASSOC)){
$projectName = $row['PROJECT_NAME'];
$html = sprintf("<option value=\"%s\">%s</option>", $projectName, $projectName);
}
$html .= "</select>";
$html .= "</div>";
print $html;
CSS Code
<style type="text/css">
select.projectSelect{ width:280px; height:24px; margin:10px; }
select.projectSelect option{line-height:24px;}
div.dropCenter{ display:inline-block; position:absolute; width:300px; height:34px; margin-left:-150px; margin-top:-17px; background-color:#e0e0e0; border:1px solid #c0c0c0; }
</style>