vue-cli的样式初始化

清除多余样式，实现高度宽度自适应，放置App.vue中

#app {
  font-family: 'Avenir', Helvetica, Arial, sans-serif;
  -webkit-font-smoothing: antialiased;
  -moz-osx-font-smoothing: grayscale;
  width:100%;
  height:100%;
}
*{
  margin:0;
  padding:0;
}
html,body{
  width:100%;
  height:100%;
}
ul{list-style:none}
a{text-decoration: none;} 
img{vertical-align:top;border:none}

.clearf:after,
.clearf:before{
    content:"";
    display:block;
    clear:both;
}