Ignite UI for Web Components is a complete library of UI components, giving you the ability to build modern web applications using encapsulation and the concept of reusable components in a dependency-free approach.
The min-height of the header content is missing. It should be 16px, in order to achieve the 32px height of the header.
The width of the Nav Drawer should be 48px. I also noticed that in Indigo the items only have paddings, while in the rest of the themes the items have paddings and margins (IMO this should be treated as an inconsistency). In Indigo these margins are applied on