ParentChildLayout:Toolkit Parent Child Layout Responsive

Build 26 on characteristics-update
1200px
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Baseline History
Build 26bca5ab0
Current build. There are unaccepted changes, so build 16 is still the baseline.
Build 16035ab45 current baseline
Accepted by Zhihao Cui.
Build 1cf98200
Auto-accepted
Commenting is disabled because there's a newer build on this branch