minor style

src/components/mark/MarkBoardTrack.vue

@@ -50,7 +50,7 @@
       </div>
     </div>
 
-    <div class="tw-flex tw-justify-between">
+    <div class="tw-flex tw-justify-between tw-mt-4">
       <div @click="clearLatestMarkOfCurrentQuetion">回退</div>
       <div @click="clearAllMarksOfCurrentQuetion">清除本题</div>
     </div>