center history bar and shrink thumbnails on remove bg page

apps/jingrow/frontend/src/views/tools/RemoveBackground.vue

@@ -604,7 +604,6 @@ h1 {
 .tool-container {
   display: flex;
   flex-direction: column;
-  gap: 24px;
 }
 
 /* 上传区域 */
@@ -911,18 +910,20 @@ h1 {
 /* 底部历史记录栏 */
 .history-bar {
   width: 100%;
-  padding: 16px 0;
-  background: white;
-  border-top: 1px solid #e5e7eb;
+  padding: 16px 0 0;
+  background: transparent;
+  border-top: none;
   margin-top: 24px;
+  display: flex;
+  justify-content: center;
 }
 
 .history-scroll-container {
   display: flex;
-  gap: 12px;
+  gap: 10px;
   overflow-x: auto;
   overflow-y: hidden;
-  padding: 0 16px;
+  padding: 0;
   scrollbar-width: thin;
   scrollbar-color: #cbd5e1 transparent;
 
@@ -946,8 +947,8 @@ h1 {
 
 .history-item {
   flex-shrink: 0;
-  width: 80px;
-  height: 80px;
+  width: 64px;
+  height: 64px;
   border-radius: 8px;
   cursor: pointer;
   transition: all 0.2s ease;
@@ -1073,11 +1074,6 @@ h1 {
     }
   }
 
-  .history-item {
-    width: 64px;
-    height: 64px;
-  }
-
   .history-scroll-container {
     gap: 8px;
     padding: 0 8px;