private string BuildHeader()
{
TestEvaluator evaluator = new TestEvaluator();
string genderInHungarian = (Subject.Gender.ToString() == "Male")? "Férfi" : "Nő";
string header = $"<head><meta charset='UTF8'> " +
"<style>table{font-family: arial, sans-serif;border-collapse: collapse;width:100%;}td,th{border: 1px solid #dddddd;text-align: left;padding: 8px;}tr:nth-child(even){background-color: #dddddd;}</style></head>" +
"<h1 style=text-align:center;background-color:lightblue;font-size:xx-large;>Teszteredmények</h1>" +
$"<p><b>tesztalany neve: {Subject.Nickname}</b></p>" +
$"<p><b>életkor: {Subject.Age}</b></p>" +
$"<p><b>nem: {genderInHungarian}</b></p>" +
$"<p><b>kitöltés időpontja: {Subject.SessionStartDate.ToString("yyyy.MM.dd HH:mm:ss")}</b></p>" +
$"<p><i><u>eredmény: {evaluator.Evaluate(Subject).ToString()}</u></i><p>" +
"<hr>";
return(header);
}