Merge remote-tracking branch 'origin/support/3.0' into develop

# Conflicts:
#	css/backoffice/pages/_csv-import.scss
#	pages/ajax.render.php

images/placeholders/skeleton-dashboard.svg

@@ -38,7 +38,7 @@
     <linearGradient id="dashboard-fill">
       <stop
               offset="0.599964"
-              stop-color="#f3f3f3"
+              stop-color="var(--skeleton-start-color)"
               stop-opacity="1"
       >
         <animate
@@ -51,7 +51,7 @@
       </stop>
       <stop
               offset="1.59996"
-              stop-color="#ecebeb"
+              stop-color="var(--skeleton-stop-color)"
               stop-opacity="1"
       >
         <animate
@@ -64,7 +64,7 @@
       </stop>
       <stop
               offset="2.59996"
-              stop-color="#f3f3f3"
+              stop-color="var(--skeleton-start-color)"
               stop-opacity="1"
       >
         <animate

images/placeholders/skeleton-list.svg

@@ -39,7 +39,7 @@
     <linearGradient id="list-fill">
       <stop
               offset="0.599964"
-              stop-color="#f3f3f3"
+              stop-color="var(--skeleton-start-color)"
               stop-opacity="1"
       >
         <animate
@@ -52,7 +52,7 @@
       </stop>
       <stop
               offset="1.59996"
-              stop-color="#ecebeb"
+              stop-color="var(--skeleton-stop-color)"
               stop-opacity="1"
       >
         <animate
@@ -65,7 +65,7 @@
       </stop>
       <stop
               offset="2.59996"
-              stop-color="#f3f3f3"
+              stop-color="var(--skeleton-start-color)"
               stop-opacity="1"
       >
         <animate

images/placeholders/skeleton-object.svg

@@ -44,7 +44,7 @@
     <linearGradient id="object-fill">
       <stop
               offset="0.599964"
-              stop-color="#f3f3f3"
+              stop-color="var(--skeleton-start-color)"
               stop-opacity="1"
       >
         <animate
@@ -57,7 +57,7 @@
       </stop>
       <stop
               offset="1.59996"
-              stop-color="#ecebeb"
+              stop-color="var(--skeleton-stop-color)"
               stop-opacity="1"
       >
         <animate
@@ -70,7 +70,7 @@
       </stop>
       <stop
               offset="2.59996"
-              stop-color="#f3f3f3"
+              stop-color="var(--skeleton-start-color)"
               stop-opacity="1"
       >
         <animate

images/placeholders/skeleton.svg

@@ -39,7 +39,7 @@
     <linearGradient id="misc-fill">
       <stop
               offset="0.599964"
-              stop-color="#f3f3f3"
+              stop-color="var(--skeleton-start-color)"
               stop-opacity="1"
       >
         <animate
@@ -52,7 +52,7 @@
       </stop>
       <stop
               offset="1.59996"
-              stop-color="#ecebeb"
+              stop-color="var(--skeleton-stop-color)"
               stop-opacity="1"
       >
         <animate
@@ -65,7 +65,7 @@
       </stop>
       <stop
               offset="2.59996"
-              stop-color="#f3f3f3"
+              stop-color="var(--skeleton-start-color)"
               stop-opacity="1"
       >
         <animate