[IMP] web_editor, website: preserve tabs in modals

addons/web_editor/static/src/less/web_editor.ui.components.less

@@ -215,8 +215,8 @@ body .modal {
         width: 80%;
 
         .modal-body {
-            .nav-tabs .active > a:not([href="#editor-media-icon"]) {
-                background-color: @o-we-color-paper;
+            .nav-tabs .active > a[href="#editor-media-icon"] {
+                background-color: white;
             }
 
             li.search {

addons/web_editor/static/src/less/web_editor.variables.less

@@ -159,6 +159,31 @@
     }
 }
 
+.o-w-preserve-tabs() {
+    .nav-tabs {
+        border-bottom: 1px solid @gray-lighter;
+
+        > li  {
+            > a {
+                line-height: 1.42857143;
+                color: @o-we-color-light;
+                &:hover {
+                    border-color: @gray-lighter;
+                }
+            }
+
+            &.active > a {
+                &, &:hover, &:focus {
+                    color: @o-we-color-normal;
+                    background-color: @o-we-color-paper;
+                    border-color: @gray-lighter;
+                    border-bottom-color: transparent;
+                }
+            }
+        }
+    }
+}
+
 .o-w-preserve-btn() {
     .btn:not(.o_btn_preview) {
         border-width: 1px;

addons/website/static/src/less/website.ui.components.less

@@ -43,6 +43,7 @@ body .modal {
         .o-w-preserve-btn();
         .o-w-preserve-wells();
         .o-w-preserve-modals();
+        .o-w-preserve-tabs();
 
         button.close {
             .o-w-close-icon(12px);