下拉框不显示边框

<el-select v-model="timer"class="select_class">
   <el-option
      v-for="item in options"
      :key="item.value"
      :label="item.label"
      :value="item.value">
   </el-option>
</el-select>

 data() {
    return {
      timer: "2",
      options: [
        { label: "月", value: "1" },
        { label: "周", value: "2" },
        { label: "日", value: "3" }
      ]
    };
  },

<style lang="scss" scoped>
.echarts_class {
  display: flex;
  justify-content: space-between;
  .select_class {
    border: none;
    .el-input--medium .el-input__inner {
      border: none; // 隐藏selsec边框
    }
  }
}

折线图数据渲染，点我主页