fix(yasgui): even out the side panel spacing around its buttons

The icon rail had 12px on the left of its buttons but only 2px on the
right, next to the card. Give the rail 12px on both sides, and drop the
open panel's left padding from 16px to 12px to match.

Closes #231

Author: MathiasVDA

packages/yasgui/src/sidePanel/SidePanel.scss

@@ -27,8 +27,9 @@
       flex-direction: column;
       align-items: center;
       gap: 4px;
-      width: 52px;
-      padding: 4px 0 16px 12px;
+      // Same 12px on both sides, so the buttons sit as far from the card as from the window edge
+      width: 60px;
+      padding: 4px 12px 16px;
       box-sizing: border-box;
     }
 
@@ -78,7 +79,7 @@
       width: var(--yasgui-side-panel-width, 300px);
       min-width: 0;
       min-height: 0;
-      padding: 4px 12px 16px 16px;
+      padding: 4px 12px 16px;
       box-sizing: border-box;
     }