#728 accessibility theming (#1057)

* [CST-3763] Change base theme colors

* [CST-3763] added new custom variables

* [CST-3763] applied changes to the header in order to have two different navbar

* [CST-3763] applied changes to breadcrumbs navbar

* [CST-3763] fix sidebar colors

* [CST-3763] applied changes footer in order to have two different sections

* [CST-3763] change home news jumbotron background color

* [CST-3763] fix issue with search-navbar.component z-index

* [CST-3763] fix issue with search-form.component that didn't use the brand colo parameter

* [CST-3763] fix issue with menu navbar on small window view

* [CST-3763] changed position for browse all button in the access control pages

* [CST-3763] Change form.component in order to have possibilities to display better additional form buttons

* [CST-3763] Change confirmation-modal.component in order to allow different colors and icons for confirm button

* [CST-3763] added confirmation icon

* [CST-3763] fixed accessibility for admin access control components

* [CST-3763] Added placeholder for search boxes

* [CST-3763] Added repository logo alt label

* [CST-3763] Adjust notification icons

* [CST-3763] Fix issue with hideReturnButton param in edit-comcol-page.component that was not initialized on page refresh

* Accessibility fix

* [CST-3763] Adjust usability for community/collection edit

* [CST-3763] fix error while running test

* [CST-3763] Added dynamically a title prefix to all dspace page

* [CST-3763] add breadcrumbs to the page where are missing

* [CST-3763] fixed failed tests

* [CST-3763] fixed failed e2e test

* [CST-3763] fixed failed e2e test

* Buttons fixes for accessibility

* [CST-3973] fixed issue with redirect after changing language

* Buttons and sections fixes for accessibility

* Buttons and sections fixes for accessibility

* [CST-3763] fixed colors for chips component

* [CST-3977] fixed issue with selecting a tag submission field

* [CST-3763] add breadcrumbs to the page where are missing

* [CST-3763] fixed edit workflowitem buttons color

* [CST-3977] removed unintentional committed log

* [CST-3763] Fix issue with tab selection in item edit page

* [CST-3763] Fix position of back button in the item edit page

* [CST-3763] icon and colors for search and browse all buttons

* [CST-3763] added atkinson font

* [CST-3763] remove dspace logo from home news

* [CST-3763] fix buttons colors for administrative search

* [CST-3763] Change background color for user menu

* [CST-3763] remove gradient from home page news component

* [CST-3763] fix issue with edit dso button

* [CST-3763] revert color schema

* [CST-3763] remove Atkinson-Hyperlegible font

* [CST-3763] fix use of header-logo-height variable

* [CST-3763] fix homepage link color

* [CST-3763] fix contrast color issue for navbar menu entries

* [CST-3763] add variable to show/hide top footer container

* [CST-3763] change dso edit button style

* [CST-3763] ensure to use "back" and "save" labels

* [CST-3763] Remove border from header

* [CST-3763] Change header in order to have only navigation bar in a single row

* Update src/app/root/root.component.html

Co-authored-by: Art Lowel <art.lowel@gmail.com>

* [CST-3763] Fix issue with wrong grid-breakpoints that cause issue on navbar collapsing

* [CST-3763] Fix issue with language dropdown when navbar is collapsed

* [CST-3763] Fix issue after merging

Co-authored-by: Matteo Perelli <matteo.perelli@4science.it>
Co-authored-by: Art Lowel <art.lowel@gmail.com>

src/styles/_bootstrap_variables.scss

@@ -1,5 +1,3 @@
-// @import '_themed_bootstrap_variables';
-
 /** Help Variables **/
 $fa-fixed-width: 1.25rem !default;
 $icon-padding: 1rem !default;
@@ -22,12 +20,12 @@ $gray-600: lighten($gray-base, 73.3%) !default; // #bbb
 $gray-100: lighten($gray-base, 93.5%) !default; // #eee
 
 /* Reassign color vars to semantic color scheme */
-$blue:      #2B4E72 !default;
-$green: #94BA65 !default;
-$cyan: #2790B0 !default;
+$blue:   #2B4E72 !default;
+$green:  #94BA65 !default;
+$cyan:   #006666 !default;
 $yellow: #ec9433 !default;
-$red: #CF4444 !default;
-$dark: darken($blue, 17%) !default;
+$red:    #CF4444 !default;
+$dark:   darken($blue, 17%) !default;
 
 $theme-colors: (
         primary: $blue,
@@ -49,12 +47,4 @@ $navbar-light-toggler-icon-bg: url("data:image/svg+xml;charset=utf8,<svg+viewBox
 
 $enable-shadows: true !default;
 
-$grid-breakpoints: (
-        xs: 0,
-        sm: (576px - $collapsed-sidebar-width),
-        md: (768px - $collapsed-sidebar-width),
-        lg: (992px - $collapsed-sidebar-width),
-        xl: (1200px - $collapsed-sidebar-width)
-) !default;
-
 $yiq-contrasted-threshold:  165 !default;