Merge pull request #4107 from metabase/chart-polish

frontend/src/metabase/css/dashboard.css

frontend/src/metabase/css/query_builder.css

frontend/src/metabase/dashboard/components/DashboardGrid.jsx

frontend/src/metabase/lib/dom.js

frontend/src/metabase/lib/visualization_settings.js

frontend/src/metabase/visualizations/Scalar.jsx

...d/src/metabase/visualizations/components/CardRenderer.jsx

...c/metabase/visualizations/components/LineAreaBarChart.css

...c/metabase/visualizations/components/LineAreaBarChart.jsx

...nd/src/metabase/visualizations/lib/LineAreaBarRenderer.js

frontend/src/metabase/visualizations/lib/tooltip.js

frontend/test/unit/support/visualizations.js

...t/unit/visualizations/lib/LineAreaBarRenderer-bar.spec.js

...it/visualizations/lib/LineAreaBarRenderer-scatter.spec.js