下划线显示优化（不要离鼠标点击处太远）

src/features/mark/SpecialTagModal.vue

@@ -32,8 +32,8 @@
         乄
       </div>
       <div
-        @click="toggleTag('_____')"
-        :class="[store.currentSpecialTag === '_____' && 'tag-selected', 'tag']"
+        @click="toggleTag('——')"
+        :class="[store.currentSpecialTag === '——' && 'tag-selected', 'tag']"
         style="width: 60px"
       >
         <u>下划线</u>