Theme switch support (#3568)

### What problem does this PR solve?
- [x] New Feature (non-breaking change which adds functionality)

---------

Co-authored-by: Yingfeng <yingfeng.zhang@gmail.com>
Co-authored-by: Jin Hai <haijin.chn@gmail.com>

web/src/components/message-input/index.less

@@ -1,6 +1,6 @@
 .messageInputWrapper {
   margin-right: 20px;
-  background-color: #f5f5f8;
+  background-color: rgba(255, 255, 255, 0.1);
   border-radius: 8px;
   :global(.ant-input-affix-wrapper) {
     border-bottom-right-radius: 0;