it doesn't work when i use v-bind of Vuejs to get the px number

[Massionter]

just like below in Vue.js, it doesn't work. The 'left' and 'top' can't change to rem.

<ul
    v-show="visible"
   :style="{left: contextMenuLeft + 'px', top: contextMenuTop + 'px'}"
   class="contextmenu"
 >
   <li v-for="(item, key) of menuList" @click="handleTagsOption(key)" :key="key">{{item}}</li>
 </ul>