:bulb: Implement sheet style
:lipstick: Remove useless CSS
:bulb: Update channels colors
:bulb: Bundle keyboard and notes on a sheet
:bulb: Update logo border
:bug: Don't call undefined method in Main
:bulb: Don't make icons white on white bg
:bug: Fix wrong file name
:bulb: Comply with Material spec

Add animation for music sheet, turn title bar into system bar, no longer
displaying title, use standard system actions icons, reduce system bar
height, add swift transitions to app bar.