FIX: Adjustments to the admin sidebar following recent core sidebar styling changes (#29138)

app/assets/stylesheets/common/base/menu-panel.scss

@@ -93,7 +93,7 @@
   }
 
   .sidebar-filter {
-    width: calc(320px - 2 * var(--d-sidebar-row-horizontal-padding));
+    width: 100%;
   }
 }
 
@@ -349,7 +349,7 @@
   }
 
   .sidebar-panel-header__row {
-    width: calc(320px - 2 * var(--d-sidebar-row-horizontal-padding));
+    width: 100%;
   }
 
   .sidebar-sections {

app/assets/stylesheets/common/base/sidebar.scss

@@ -304,11 +304,8 @@
 .sidebar-filter {
   margin-top: 1em;
   margin-bottom: 1em;
-  display: flex;
   border: 1px solid var(--primary-400);
   border-radius: var(--d-input-border-radius);
-  align-items: center;
-  justify-content: space-between;
   background: var(--secondary);
   width: calc(
     var(--d-sidebar-width) - 2 * var(--d-sidebar-row-horizontal-padding)
@@ -371,8 +368,6 @@
   display: flex;
   justify-content: space-between;
   align-items: baseline;
-  margin: 0 var(--d-sidebar-row-horizontal-padding) 0
-    var(--d-sidebar-row-horizontal-padding);
   color: var(--d-sidebar-link-color);
   width: calc(
     var(--d-sidebar-width) - 2 * var(--d-sidebar-row-horizontal-padding) + 2px

app/assets/stylesheets/desktop/menu-panel.scss

@@ -45,7 +45,6 @@
       .sidebar-section-header-wrapper {
         margin: 0 0 0.5em;
         padding-bottom: 0.25em;
-        border-bottom: 1px solid var(--primary-low);
         .d-icon-globe {
           color: var(--primary-medium);
         }

app/assets/stylesheets/mobile/menu-panel.scss

@@ -21,7 +21,6 @@
   --d-sidebar-row-horizontal-padding: 1rem;
   --d-sidebar-highlight-backgrond: var(--primary-low);
   box-sizing: border-box;
-  padding: 0;
 
   .panel-body-contents {
     .sidebar-hamburger-dropdown {