chore: test adjustments and minor layout adjustments

CHANGELOG.md

development/issues/closed/186.html

development/issues/closed/186.mjs

source/components/datatable/style/datatable.pcss

.../components/datatable/style/filter-controls-defaults.pcss

...ponents/datatable/stylesheet/filter-controls-defaults.mjs

source/components/form/field-set.mjs

source/components/form/form.mjs

source/components/form/stylesheet/field-set.mjs

source/components/form/stylesheet/form.mjs

source/components/form/stylesheet/select.mjs

source/components/layout/style/collapse.pcss

source/components/layout/stylesheet/collapse.mjs

test/cases/components/form/form.mjs

test/cases/components/host/details.mjs

test/cases/components/host/host.mjs

test/cases/components/host/overlay.mjs

test/cases/dom/customcontrol.mjs

test/cases/dom/customelement.mjs