New viewport units
This post is 3 years old — some details may be outdated.
Difficulties dealing with viewport sizing are prominent in both the MDN Browser Compatibility Report 2020 and the new State of CSS 2021 survey. CSS Values and Units Level 4 adds new units for the largest, smallest, and dynamic viewport sizes, lv*, sv*, and dv*. These units will make it easier to create layouts that fill the visible viewport on mobile devices while taking the address bar into account.
Additionally, the cross vendor team behind Interop 2022 will collaborate on researching and improving the state of interoperability of existing viewport measurement features, including the existing vh unit.