Keep interpolation in var CSS function #146

Job	Run time
Dart tests \| Dart stable \| ubuntu-latest	1m 6s
Node tests \| Dart stable \| Node 18 \| ubuntu-latest	1m 0s
Dart tests \| Dart stable \| windows-latest	2m 4s
Static analysis	22s
Node tests \| Dart stable \| Node 18 \| windows-latest	1m 48s
Dart tests \| Dart stable \| macos-latest	3m 59s
Node tests \| Dart stable \| Node 18 \| macos-latest	2m 5s
Node tests \| Dart stable \| Node 16 \| ubuntu-latest	1m 3s
Node tests \| Dart stable \| Node 14 \| ubuntu-latest	1m 6s
Node tests \| Dart dev \| Node \| ubuntu-latest	1m 10s
Sanity checks	0s
Deploy Github: Linux	0s
Deploy Pub	0s
Deploy Homebrew	0s
Deploy npm	0s
Deploy Github: Windows	0s
Deploy Github: Mac OS	0s
	15m 43s

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