enhance(ui): polish the main container background color

src/main/frontend/components/container.css

@@ -13,8 +13,8 @@
 }
 
 #app-container {
-  display: flex;
-  flex: 0 0 100%;
+  @apply flex basis-full;
+  background-color: or(--lx-gray-01, --ls-primary-background-color, #fff);
 }
 
 #skip-to-main {
@@ -555,10 +555,6 @@
   background-color: or(--ls-main-content-background, --lx-gray-01, --ls-primary-background-color);
 }
 
-.dark .cp__sidebar-main-layout {
-  background-color: or(--ls-main-content-background, --lx-gray-02, --ls-primary-background-color);
-}
-
 .cp__sidebar-main-content {
   width: 100%;
   max-width: var(--ls-main-content-max-width);

src/main/frontend/components/theme.css

@@ -60,8 +60,6 @@
 }
 
 html[data-theme='light'] #app-container {
-  background-color: or(--lx-gray-01, --ls-primary-background-color, #fff);
-
   .form-checkbox {
     &:focus {
       border-color: var(--ls-page-checkbox-border-color);
@@ -78,8 +76,6 @@ html[data-theme='light'] #app-container {
 }
 
 html[data-theme='dark'] #app-container {
-  background-color: or(--lx-gray-02, --ls-primary-background-color, #333);
-
   input.form-input {
     background: none;
   }