feat: use localStorage instead of sessionStorage and adjust styles for dark mode

- Replace sessionStorage with localStorage for saving background color ID
- Update CSS to improve dark mode styling:
  - Remove background color from layuimini-main
  - Add background color and other styles for tableSearch-xmSelect in dark mode

public/static/admin/css/public.css

@@ -22,7 +22,6 @@ body {
     min-height: 250px;
     padding: 15px;
     margin: 0 auto;
-    background-color: var(--lay-color-white);
 }
 
 .layuimini-main {
@@ -138,6 +137,13 @@ body {
     min-height: 30px !important;
     line-height: 30px !important;
     margin: 0 !important;
+    background-color: var(--lay-color-fill-2);
+}
+
+.elem-style-dark .tableSearch-xmSelect xm-select {
+    background-color: var(--lay-color-fill-2);
+    color: var(--lay-color-text-2);
+    border-color: var(--lay-color-border-1) !important;
 }
 
 /** 按钮背景色 */

public/static/plugs/lay-module/layuimini/miniTheme.js

@@ -487,7 +487,7 @@ define(["jquery"], function ($) {
          */
         buildBgColorHtml: function (options) {
             options.bgColorDefault = options.bgColorDefault || 0;
-            var bgcolorId = parseInt(sessionStorage.getItem('layuiminiBgColorId'));
+            var bgcolorId = parseInt(localStorage.getItem('layuiminiBgColorId'));
             if (isNaN(bgcolorId)) bgcolorId = options.bgColorDefault;
             var bgColorConfig = miniTheme.config();
             var html = '';
@@ -550,7 +550,7 @@ define(["jquery"], function ($) {
                 var bgcolorId = $(this).attr('data-select-bgcolor');
                 $('.layuimini-color .color-content ul .layui-this').attr('class', '');
                 $(this).attr('class', 'layui-this');
-                sessionStorage.setItem('layuiminiBgColorId', bgcolorId);
+                localStorage.setItem('layuiminiBgColorId', bgcolorId);
                 miniTheme.render({
                     bgColorDefault: bgcolorId,
                     listen: false,