improve main menu collapse toggle visibility. hide per default and show on hover

app/assets/stylesheets/layout/_main_menu.sass

@@ -209,6 +209,8 @@ $toggler-width: 40px
       border-left-width: 2px
       border-left-style: solid
       @include varprop(border-left-color, primary-color)
+      a.navigation-toggler
+        visibility: visible
     &.show
       left: calc(#{$main-menu-folded-width} - 1px)
       a.navigation-toggler
@@ -216,6 +218,7 @@ $toggler-width: 40px
           @include icon-mixin-arrow-right2
     a.navigation-toggler
       @include default-transition
+      visibility: hidden
       position: absolute
       top: 0
       height: 40px

app/assets/stylesheets/layout/_work_packages_full_view.sass

@@ -169,7 +169,7 @@ body.controller-work_packages.full-create
     display: none
 
 .work-packages--show-view
-  padding: 0 15px
+  padding: 0 20px
 
   .wp-show--header-container
     @media only screen and (max-width: 679px)