[dspillett]

> purely design and doesn't serve a functional purpose it would be fine

Or if it does provide functional information (traffic-light style status displays for instance), it is fine if the information is also carried by other means.

> do it in Black and White first ... then add colors.

Exactly. That way anyone with reasonable vision[1] can use the result and it is enhanced for those with good colour vision, rather than requiring good colour vision to be properly usable.

[1] Other serious visual impairments (up to and including complete blindness) should be considered too where possible, of course. Keep contrast high, try to design with screen readers and other common aids in mind, ...

[zaarn]

For Screen Readers I've found it helpful to use elinks or lynx to develop the initial HTML.

If your application remains readable and functional on a terminal output, chances are high a screen reader can handle it (since I can't afford any of the screen readers people seem to use, that's what I'm stuck with, aside from following general guidelines on this)

Progressive enhancing, the process of having a working HTML page, enhance with CSS/Images and then enhance with JS, is sadly a rather lost art in modern webdevs.