I am working on a technical ebook but I have concentrated so far only in the content. Are there any resources to help me to make the book more visually appealing and thus more pleasurable to read. I like minimal style, big font-size, lots of white space. For example, I like the style at csstricks.com and the No-Starch Press books. Do you have any other examples that I can review for inspiration?.All my files are written in Markdown and although the PDF generated is quite "nice" I want to take it to a higher level.