update bg and readme

README-en.md

@@ -46,6 +46,12 @@ Then clone it to your local machine.
 
 For details about environment variables, see: <b>[EnvVariables-en.md](docs/EnvVariables-en.md)</b>
 
+- Install dependencies
+
+  ```shell
+  npm install
+  ```
+
 - Local development
 
   ```shell

README.md

@@ -47,6 +47,12 @@
 
 有关环境变量的说明详见：<b>[EnvVariables.md](docs/EnvVariables.md)</b>
 
+- 安装依赖
+
+  ```shell
+  npm install
+  ```
+
 - 本地调试
 
   ```shell

src/styles/global.css

@@ -87,10 +87,17 @@ html.dark body::after {
 
 @media (max-width: 900px) {
   body::after {
-    opacity: 0.06;
+    opacity: 0.1;
   }
 }
 
+@media (max-width: 700px) {
+  body::after {
+    opacity: 0;
+  }
+}
+
+
 * {
   box-sizing: border-box;
 }