reorganize btn-basis placeholder

apps/app/src/components/Sidebar/PageCreateButton/CreateButton.module.scss

@@ -3,7 +3,7 @@
 @use '../button-styles';
 
 .btn-create :global {
-  @extend %btn-primary-basis;
+  @extend %btn-basis;
 
   padding: 0 3px;
 

apps/app/src/components/Sidebar/SidebarHead/ToggleCollapseButton.module.scss

@@ -5,7 +5,7 @@
 @use '../button-styles';
 
 .btn-toggle-collapse :global {
-  @extend %btn-primary-basis;
+  @extend %btn-basis;
 
   $height: var.$grw-sidebar-nav-width; // declare $height with the same value as the sidebar nav width
   height: $height;

apps/app/src/components/Sidebar/SidebarNav/PrimaryItems.module.scss

@@ -1,13 +1,14 @@
 @use '@growi/core/scss/bootstrap/init' as bs;
 
 @use '~/styles/variables' as var;
+
 @use '../button-styles';
 
 @use './variables' as sidebarNavVar;
 
 .grw-primary-items :global {
   .btn {
-    @extend %btn-primary-basis;
+    @extend %btn-basis;
 
     width: var.$grw-sidebar-nav-width;
     height: sidebarNavVar.$grw-sidebar-primary-button-height;

apps/app/src/components/Sidebar/SidebarNav/SecondaryItems.module.scss

@@ -1,13 +1,16 @@
 @use '@growi/core/scss/bootstrap/init' as bs;
 
+@use '~/styles/variables' as var;
+
 @use '../button-styles';
 
 @use './variables' as sidebarNavVar;
 
 .grw-secondary-items :global {
   .btn {
-    @extend %btn-primary-basis;
+    @extend %btn-basis;
 
+    width: var.$grw-sidebar-nav-width;
     height: sidebarNavVar.$grw-sidebar-primary-button-height;
 
     i {

apps/app/src/components/Sidebar/_button-styles.scss

@@ -1,6 +1,6 @@
 @use '~/styles/variables' as var;
 
-%btn-primary-basis {
+%btn-basis {
   --bs-btn-padding-x: 0;
   --bs-btn-padding-y: 0;