The magic is the quirks in how `display: table-cell` makes it like a block, but only as wide as the text, then the pseudo element with equals signs is positioned absolutely inside. Fortunately, most browsers allow this, but firefox doesn't let things be positioned absolute inside a `table-cell`, so I make FF just fall back to `display: block` https://github.com/mrcoles/markdown-css/blob/master/markdown...