fix:【问题管理】添加关联问题时，问题过长下拉组件样式优化(#80) (#129)

ui/src/styles/element-plus.scss

@@ -319,3 +319,8 @@
   padding-left: 12px !important;
   padding-right: 12px !important;
 }
+
+// select下拉框
+.select-popper {
+  max-width: 300px;
+}

ui/src/views/paragraph/component/ProblemComponent.vue

@@ -25,13 +25,17 @@
           @change="addProblemHandle"
           @blur="isAddProblem = false"
           class="mb-16"
+          popper-class="select-popper"
+          :popper-append-to-body="false"
         >
           <el-option
             v-for="item in problemOptions"
             :key="item.id"
             :label="item.content"
             :value="item.id"
-          />
+          >
+            {{ item.content }}
+          </el-option>
         </el-select>
         <template v-for="(item, index) in problemList" :key="index">
           <TagEllipsis