CSSGrid:CSSGrid with responsive props

Build 435 on add-page-loader
1200px
Reviewing disabled
The baseline is taller than the new snapshot (680x240 to 680x72).
Baseline History
Build 43500ced2d
Current build. There are unaccepted changes, so build 434 is still the baseline.
Build 434009ca62 current baseline
Accepted by Christopher Pappas.
Build 431eaf2e52
Auto-accepted
Build 430169769b
Accepted by Kieran.
Build 42948f8897
Auto-accepted
Commenting is disabled because there's a newer build on this branch