Played around with the templates to strip most of the styling and put them in CSS. Here are the revised .tpl files (header, footer, index, category & books_section) along with some sample stylesheets. The file stylesheet.css
must be in the same folder as index.php.
001: uses the original styles (stylesheet.css is a copy of this file)
002: similar to original style but uses different font
003 & 004: changed header/footer background color, added button styling
005: similar to 004, added background color
Also working on a template for something more mobile-friendly.
Not really particularly artistic. Hopefully, someone with a more artistic bent will modify the CSS to something more pleasing to the eye.