Markdown renders tabs as 4 spaces, but browsers traditionally render tabs using a width of 8, so they look like 8 spaces in the edit box. It is possible to override the display tab size using the relatively new CSS tab-size property. I'd like for that to be done so that the width of tabs in the edit box is the same as it is in the output.

https://developer.mozilla.org/en-US/docs/Web/CSS/tab-size

http://dev.w3.org/csswg/css-text-3/#tab-size-property