Impressive!

Like the Yosemite look, this app is really a well made Mac style developer tool. The CSS design options are pretty impressive, the timeline system is incredible.
If you’re serious about web design you should add this one in you toolkit (I wouldn’t say it’s an alternative to Espresso or Coda, it’s just something else, a more advanced tool, where Espresso/Coda are more for beginners IMO).
Keep up the good work!

Mitttsh about Xpressive