fix: tabbar safe-bottom样式异常 (#1742)

src/packages/__VUE/tabbar/index.scss

@@ -12,7 +12,7 @@
   display: flex;
   align-items: center;
   height: 50px;
-  box-sizing: border-box;
+  box-sizing: content-box;
   background: $white;
 
   &:last-child {

src/packages/__VUE/tabbaritem/index.scss

@@ -72,6 +72,7 @@
       display: block;
       background-size: 100% 100%;
       background-position: center center;
+      margin-bottom: 4px;
     }
     &_nav-word {
       font-size: $tabbar-item-text-font-size;