[FIX] m.IconTabBar: HCB theme, fix for icon alignment in some browsers

The small icons, created with ::after, are not properly aligned on all browsers. They should be positioned at the bottom, but on native android and safari on mac they appear vertically centered instead.

Change-Id: Ifb8c9e8bd1c50af4ec6ff7f6e87e0dbc3ab86e72
Merge "[FIX] m.IconTabBar: HCB theme, fix for icon alignment in some browsers"