Small tweaks to TUX on resize & scroll events

* Animate width changes with CSS transitions
* Use member variables instead of finding header and actions from DOM
* Use slightly larger delay to avoid small misplacements due to skin transitions
* Reflow header and actions both on scroll and resize
* Unset width when defloating so that the items get automatic width

Change-Id: Iadc9bcd0219a8e78a6011ffc209b663b18ec9da2