So I'm used to debugging in Chrome, so I instinctively open the browser's dev tools to find that this breaks the Live Preview. It feels somewhat like there's a quantum property here: things work like magic (the browser is apparently opening a static CSS file from file://), but as soon as you try to observe it, it starts behaving as expected (no live updates for you!). That seems a little bit odd.
Brackets core contributor here... The reason for this is the webkit remote debugging API is used both by Brackets' "live preview" as well as by the developer tools panel. The remote debugging API only allows one connection at a time, so one kicks the other off the connection.
