#3135 ambiance: locked notebook cells should have no borders
#3135 ambiance: locked notebook cells should have no borders

ScottPJones/beaker-notebook,vital-ai/beaker-notebook,vital-ai/beaker-notebook,ScottPJones/beaker-notebook,ScottPJones/beaker-notebook,vital-ai/beaker-notebook,vital-ai/beaker-notebook,vital-ai/beaker-notebook,vital-ai/beaker-notebook,vital-ai/beaker-notebook,ScottPJones/beaker-notebook,ScottPJones/beaker-notebook