The DOM is actually a tree. I'm not sure if it's correct to call that 1D. Similarly, the web is a graph, definitely not 1D. I'd even go as far to say the text

The DOM is actually a tree. I'm not sure if it's correct to call that 1D. Similarly, the web is a graph, definitely not 1D. I'd even go as far to say the text on most webpages isn't even linear. It's either a tree (like this comment page) or a fragmented collection of text chunks. The webpage that strictly consists of one linear stream of text is very much the exception. And it also happens to be the exception that CSS never had problems with. What you seem to be saying is that paragraphs are 1D (which get wrapped and flowed in layout), therefore entire webpages are 1D (no) and therefore the web is 1D (definitely not). Or maybe you could say that most viewport representations, scrolling vertically, are 1D. In which case CSS should be the tool that converts the tree or graph of content into this semi-1D viewing representation. I agree that this mismatch is where CSS finds a lot of problems.