Refactoring SCSS

subato-web/src/app/app.component.scss

...b/src/app/courses/pages/course/course.page.component.scss

...xercise-form/task-instances/task-instances.component.scss

...eb/src/app/layout/components/footer/footer.component.scss

...eb/src/app/layout/components/header/header.component.scss

...components/horizontal-menu/horizontal-menu.component.scss

subato-web/src/app/layout/layout.module.ts

.../src/app/layout/layouts/one-column/one-column.layout.scss

...pp/layout/layouts/three-columns/three-columns.layout.scss

...rc/app/layout/layouts/two-columns/two-columns.layout.scss

subato-web/src/app/layout/store/layout.effects.ts

...to-web/src/app/layout/styles/partials/_angular-split.scss

subato-web/src/app/layout/styles/partials/_bootstrap.scss

subato-web/src/app/layout/styles/partials/_fullscreen.scss

...o-web/src/app/layout/styles/partials/_global-spinner.scss

subato-web/src/app/layout/styles/partials/_label.scss

...o-web/src/app/layout/styles/partials/_misconceptions.scss

subato-web/src/app/layout/styles/partials/_nebular.scss

...o-web/src/app/layout/styles/partials/_ngx-codemirror.scss

subato-web/src/app/layout/styles/partials/_ngx-slider.scss