优化splitpane提示

src/features/mark/MarkBoardTrack.vue

@@ -133,6 +133,7 @@
           background-color: grey;
           cursor: row-resize;
         "
+        class="split-pane"
       ></div>
       <div
         class="tw-flex tw-flex-wrap tw-mt-5 tw-overflow-auto tw-content-start"
@@ -421,4 +422,26 @@ const buttonHeightForSelective = $computed(() =>
   background-color: #4db9ff;
   border: none;
 }
+.split-pane::before {
+  content: "";
+  display: block;
+  margin: 0 auto;
+  margin-top: -7px;
+  width: 20px;
+  height: 4px;
+  text-align: center;
+  clip-path: polygon(0 100%, 100% 100%, 50% 0);
+  background-color: lightskyblue;
+}
+.split-pane::after {
+  content: "";
+  display: block;
+  margin: 0 auto;
+  margin-top: 6px;
+  width: 20px;
+  height: 4px;
+  text-align: center;
+  clip-path: polygon(0 0, 100% 0, 50% 100%);
+  background-color: lightskyblue;
+}
 </style>