Sorry, I presumed given you had posted HTML code that you were looking for what the HTML / CSS was. The Element Library is just an example of each type of table, if you view the source code for the page you can see what classes have been used to achieve that effect. I agree that there isn't an easy way to build a table with borders just using TinyMCE, you may actually find it easier to make the tables (without adding borders, etc.) and then tweak the HTML afterwards to replace <table> with <table class="generaltable">

Regards

Dan