docs(grid): 使用css变量解决Grid组件组件黑暗主题下背景颜色错误 (DevCloudFE#825)

Author: liyao1520

packages/devui-vue/docs/components/grid/index.md

@@ -49,11 +49,10 @@
  line-height: 44px;
 }
 .docs-devui-row .devui-col:nth-of-type(2n + 1) {
- background: #f8f8f8;
+ background: var(--devui-global-bg);
 }
 .docs-devui-row .devui-col:nth-of-type(2n) {
- background: #99b0ff;
- color: #fff;
+ background: var(--devui-brand);
 }
 </style>
 ```
@@ -187,10 +186,10 @@
  background: transparent !important;
 }
 .col-gutter:nth-of-type(2n + 1) > .col-child {
- background: #f8f8f8;
+ background: var(--devui-global-bg);
 }
 .col-gutter:nth-of-type(2n) > .col-child {
- background: #99b0ff;
+ background: var(--devui-brand);
 }
 </style>
 ```