Polishing: Courseware Layout

resources/assets/stylesheets/mixins/colors.scss

resources/assets/stylesheets/scss/courseware/blockadder.scss

...ets/stylesheets/scss/courseware/blocks/default-block.scss

...esheets/scss/courseware/containers/default-container.scss

...s/assets/stylesheets/scss/courseware/containers/tabs.scss

...sets/stylesheets/scss/courseware/layouts/collapsible.scss

.../assets/stylesheets/scss/courseware/layouts/radioset.scss

...es/assets/stylesheets/scss/courseware/layouts/ribbon.scss

...rces/assets/stylesheets/scss/courseware/layouts/tabs.scss

...rces/assets/stylesheets/scss/courseware/layouts/tree.scss

...ssets/stylesheets/scss/courseware/structural-element.scss

resources/assets/stylesheets/scss/courseware/toolbar.scss

resources/assets/stylesheets/scss/variables.scss

resources/assets/stylesheets/scss/wizard.scss

...mponents/courseware/tasks/CoursewareDashboardStudents.vue

...s/vue/components/courseware/tasks/PagesTaskGroupsShow.vue

resources/vue/components/courseware/tasks/TaskGroup.vue