I found a system for pixel art in PHP by using box-shadow: parameters in CSS.
There's a small codebase now for pixelart on-the-fly editting and displaying, in phpHackerPortal.

Then I wrote some javascript support code for the project to change HTML elements in PHP/JS.

Project will be moved to savannah.gnu.org but for now is at https://github.com/zork9/php.portal