Enhancement: Added drop shadows to markdown, text, and tree views (#6893)

* Added Drop Shadows

Adjusted drop shadows for tree view, markdown and text notebooks.

* Update: Corrected Tree View Shadows

Tree View drop shadow values are in co-ordination with the others.

* Responsive padding for main-panel

Adjusted main-panel padding to be responsive

* Update: media-query rearranged

* Update: Body selectors with filters

Added data-format body selectors to the css

* Re-written media query

Re-wrote the media query for allowing responsiveness without a refresh

* Update Playwright Snapshots

* Update Playwright Snapshots

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Co-authored-by: github-actions[bot] <github-actions[bot]@users.noreply.github.com>

Author: rielAsh24

packages/application/style/base.css

@@ -80,6 +80,10 @@ body[data-notebook='edit'] #spacer-widget-bottom {
   box-shadow: var(--jp-elevation-z4);
 }
 
+.jp-TreePanel > .lm-TabPanel-stackedPanel {
+  box-shadow: var(--jp-elevation-z4);
+}
+
 body[data-notebook='notebooks'] #main-panel {
   margin-left: unset;
   margin-right: unset;
@@ -89,3 +93,13 @@ body[data-notebook='notebooks'] #main-panel {
 body[data-notebook='notebooks'] #spacer-widget-top {
   min-height: unset;
 }
+
+#main-panel > .jp-TreePanel {
+  padding: 0px 5px;
+}
+
+@media only screen and (max-width: 760px) {
+  #main-panel > .jp-TreePanel {
+    margin: 0px -5px;
+  }
+}

packages/notebook-extension/style/base.css

@@ -152,11 +152,7 @@ body[data-notebook='notebooks'] .jp-WindowedPanel-window {
 /* Notebook box shadow */
 
 body[data-notebook='notebooks'] .jp-Notebook > *:first-child:not(:last-child) {
-  box-shadow: 0px 0px 12px 1px var(--jp-shadow-umbra-color);
-}
-
-body[data-notebook='notebooks'] .jp-Notebook > *:first-child:not(:last-child) {
-  box-shadow: 0px 0px 12px 1px var(--jp-shadow-umbra-color);
+  box-shadow: var(--jp-elevation-z4);
 }
 
 body[data-notebook='notebooks']