Table: fix layout breaks when append slot exists (#16332)

packages/table/src/table.vue

@@ -123,9 +123,7 @@
         <div
           v-if="$slots.append"
           class="el-table__append-gutter"
-          :style="{
-            height: layout.appendHeight + 'px'
-          }"></div>
+          :style="{ height: layout.appendHeight + 'px'}"></div>
       </div>
       <div
         v-if="showSummary"
@@ -183,6 +181,10 @@
             width: bodyWidth
           }">
         </table-body>
+         <div
+          v-if="$slots.append"
+          class="el-table__append-gutter"
+          :style="{ height: layout.appendHeight + 'px' }"></div>
       </div>
       <div
         v-if="showSummary"

packages/theme-chalk/src/table.scss

@@ -81,6 +81,11 @@
     width: 20px;
   }
 
+  @include e(append-wrapper) {
+    // 避免外边距重合 https://developer.mozilla.org/zh-CN/docs/Web/CSS/CSS_Box_Model/Mastering_margin_collapsing
+    overflow: hidden;
+  }
+
   @include m(fit) {
     border-right: 0;
     border-bottom: 0;