Place the Thank You Order Details Block and start customizing.
Take the container, and change the background color. Put a standard color on it so customers can read the details. Use a nice border color as well.
After that, style the heading by changing fonts, font size and so on.
Use a nice color for the heading text.
Take the table header to customize it accordingly by selecting a nice color.
Finally, coming to the footer, change the text colors of the footer also the background color.