Fix tiny issues with dropzone border to the left for fixed header and header jump by 1px when it get sticky.

src/Umbraco.Web.UI.Client/src/less/components/editor/subheader/umb-editor-sub-header.less

@@ -12,7 +12,7 @@
 .umb-editor-sub-header.-umb-sticky-bar {
    box-shadow: 0 5px 0 rgba(0, 0, 0, 0.08), 0 1px 0 rgba(0, 0, 0, 0.16);
    transition: box-shadow 1s;
-   top: 100px;
+   top: 101px; /* height of header: 100px + its bottom-border: 1px */
    transform: translate(0, 50%);
 
 }

src/Umbraco.Web.UI.Client/src/less/components/umb-file-dropzone.less

@@ -5,7 +5,7 @@
   // tall and small version - animate height
   .dropzone {
     height: 400px;
-    width: 100%;
+    width: auto;
     padding: 50px 0;
     border: 1px dashed @grayLight;
     text-align: center;