调整登录卡片位置并彻底消除白边 - 卡片左移，强化全局样式重置

demo/frontend/src/App.vue

@@ -51,28 +51,38 @@ console.log('App.vue 加载成功')
   box-sizing: border-box;
 }
 
-html, body {
+html {
   height: 100%;
   width: 100%;
   margin: 0;
   padding: 0;
-  overflow: hidden; /* 完全隐藏滚动条 */
-}
-
-body {
-  font-family: -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, 'Helvetica Neue', Arial, sans-serif;
-  line-height: 1.6;
-  color: #333;
+  overflow: hidden;
   background: transparent;
 }
 
+body {
+  height: 100%;
+  width: 100%;
+  margin: 0;
+  padding: 0;
+  overflow: hidden;
+  background: transparent;
+  font-family: -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, 'Helvetica Neue', Arial, sans-serif;
+  line-height: 1.6;
+  color: #333;
+}
+
 #app {
-  min-height: 100vh;
+  position: fixed;
+  top: 0;
+  left: 0;
   width: 100vw;
+  height: 100vh;
+  min-height: 100vh;
   display: flex;
   flex-direction: column;
-  position: relative;
   overflow: hidden;
+  background: transparent;
 }
 
 /* 全屏背景层 */

demo/frontend/src/views/Login.vue

@@ -233,7 +233,7 @@ const handleLogin = async () => {
 .login-card {
   position: absolute;
   top: 50%;
-  right: 8%;
+  right: 15%; /* 往左移动一些 */
   transform: translateY(-50%);
   width: 500px;
   background: rgba(26, 26, 46, 0.8);