页面高度及颜色修改

src/page/sampling-plan/add/loc/SelectLoc.vue

 <template>
   <div>
     <div style="display: flex">
-      <van-field name="checkboxGroup" label="省市区">
+      <van-field name="checkboxGroup" label="省市区" label-width="55">
         <template #input>
           <select id='province' @change='_locSearch'></select>
         </template>
       </van-field>
-      <van-field name="checkboxGroup" label="地级市">
+      <van-field name="checkboxGroup" label="地级市" label-width="55">
         <template #input>
           <select id='city' @change='_locSearch'></select>
         </template>
       </van-field>
-      <van-field name="checkboxGroup" label="区县">
+      <van-field name="checkboxGroup" label="区县" label-width="55">
         <template #input>
           <select id='district' @change='_locSearch'></select>
         </template>