fix(tabs): left shadow isn't displayed in card type

CHANGELOG.en-US.md

@@ -25,6 +25,7 @@
 - Fix `n-button` border on hover conflicts with `n-badge`, closes [#1195](https://github.com/TuSimple/naive-ui/issues/1195).
 - Fix `n-upload` prop `v-model:file-list` dosen't work well when prop `multiple` is `true`, closes [#418](https://github.com/TuSimple/naive-ui/issues/418).
 - Fix `useThemeVars` doesn't apply theme overrides, closes [#1194](https://github.com/TuSimple/naive-ui/issues/1194), [#1176](https://github.com/TuSimple/naive-ui/issues/1176).
+- Fix `n-tabs`'s left shadow isn't displayed in card type.
 
 ## 2.18.2 (2021-09-14)
 

CHANGELOG.zh-CN.md

@@ -25,6 +25,7 @@
 - 修复 `n-button` 在 hover 状态下边框与 `n-badge` 冲突，关闭 [#1195](https://github.com/TuSimple/naive-ui/issues/1195)
 - 修复 `n-upload` 的 `v-model:file-list` 属性在 `multiple` 属性设为 `true` 的时候没有正确更新，关闭 [#418](https://github.com/TuSimple/naive-ui/issues/418)
 - 修复 `useThemeVars` 未应用覆盖的变量值，关闭 [#1194](https://github.com/TuSimple/naive-ui/issues/1194), [#1176](https://github.com/TuSimple/naive-ui/issues/1176)
+- Fix `n-tabs` 在 card 类型时左侧滚动的阴影不显示
 
 ## 2.18.2 (2021-09-14)
 

src/tabs/src/styles/index.cssr.ts

@@ -67,25 +67,21 @@ export default cB('tabs', `
         box-shadow: inset -10px 0 8px -8px rgba(0, 0, 0, .12);
       `)
     ]),
-    c('&::before', `
+    c('&::before, &::after', `
       transition: box-shadow .3s var(--bezier);
       pointer-events: none;
       content: "";
       position: absolute;
-      left: 0;
       top: 0;
       bottom: 0;
       width: 20px;
+      z-index: 1;
+    `),
+    c('&::before', `
+      left: 0;
     `),
     c('&::after', `
-      transition: box-shadow .3s var(--bezier);
-      pointer-events: none;
-      content: "";
-      position: absolute;
       right: 0;
-      top: 0;
-      bottom: 0;
-      width: 20px;
     `)
   ]),
   cB('tabs-nav-scroll-content', `