Add active cell border padding, remove double cell padding (#7570)

* remove unsetting notebook work area / viewport padding

* remove l and r padding from .jp-Notebook-cell

* Update Playwright Snapshots

* Update Playwright Snapshots

* Update Playwright Snapshots

* Update Playwright Snapshots

* undo some snapshots updates

* more snapshot updates

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Co-authored-by: github-actions[bot] <github-actions[bot]@users.noreply.github.com>
Co-authored-by: Jeremy Tuloup <jeremy.tuloup@gmail.com>

packages/notebook-extension/style/base.css

@@ -53,8 +53,6 @@ body[data-notebook='notebooks'] .jp-WindowedPanel-inner {
 
 body[data-notebook='notebooks'] .jp-Notebook-cell {
   background: var(--jp-layout-color0);
-  padding-left: calc(2 * var(--jp-cell-padding));
-  padding-right: calc(2 * var(--jp-cell-padding));
 }
 
 /* Empty space at the bottom of the notebook (similar to classic) */
@@ -140,7 +138,6 @@ body[data-format='mobile'] .jp-ToolbarButton .jp-DebuggerBugButton {
 body[data-notebook='notebooks'] .jp-WindowedPanel-viewport {
   background: var(--jp-layout-color0);
   box-shadow: var(--jp-elevation-z4);
-  padding: unset;
 
   /* Extra padding at the top and bottom so the notebook looks nicer */
   padding-top: calc(2 * var(--jp-notebook-padding));