diff --git a/ui/src/components/session/SessionRail.vue b/ui/src/components/session/SessionRail.vue
index f7dcd62..2fcbf63 100644
--- a/ui/src/components/session/SessionRail.vue
+++ b/ui/src/components/session/SessionRail.vue
@@ -36,12 +36,13 @@ const emit = defineEmits(['open', 'goto-kg', 'goto-settings']);
 /* 兜底样式（类名按 UI_SPEC §3 / §7） */
 .collapsed-rail {
   display: flex;
-  flex-direction: row;       /* 展开态：三个图标横向一排 */
+  flex-direction: row;          /* 展开态：三个图标横向一排 */
   align-items: center;
+  justify-content: center;      /* 展开态：横向居中 */
   gap: 14px;
   width: 100%;
   padding: 0 14px 14px;
-  margin-top: auto;          /* 居底：与折叠态同一元素，切换时 Y 高度不变 */
+  margin-top: auto;             /* 居底：与折叠态同一元素，切换时 Y 高度不变 */
 }
 .rail-item {
   display: inline-flex;