[bugfix] Popup: update overlay style & class (#349)

* fix: Tabbar icon line-height

* [new feature] progress add showPivot prop

* [new feature] TabItem support vue-router

* [new feature] update document header style

* [Doc] add toast english ducoment

* [bugfix] Search box-sizing wrong

* [Doc] update vant-demo respo

* [Doc] translate theme & demo pages

* [Doc] add Internationalization document

* [bugfix] remove unnecessary props

* [fix] optimize clickoutside

* [new feature] optimize find-parent

* [new feature]: change document title accordinng to language

* [new feature] Pagination code review

* [improvement] adjust icon-font unicode

* [improvement] Icon spinner color inherit

* [improvement] icon default width

* [bugfix] DateTimePicker validate date props

* [bugfix] Tab item text ellipsis

* [improvement] optimize single line ellipsis

* [Improvement] optimzie staticClass

* [Improvement] Button: use sfc instread of jsx

* [Improvement] update actionsheet close icon style

* fix: yarn.lock

* fix: icon test cases

* [bugfix] errors during ssr

* [Improvement] SubmitBar add left slot

* [new feature] ImagePreview support manually close

* fix: ImagePreview test case

* [Doc] add switch lang button in mobile

* [bugfix] Popup overlay style update

docs/markdown/en-US/popup.md

@@ -43,6 +43,8 @@ Use `position` prop to set popup display position
 | overlay | Whether to show overlay | `Boolean` | `true` | - |
 | lockOnScroll | Lock body scroll | `Boolean` | `false` | - |
 | position | Position | `String` | - | `top` `bottom` `right` `left` |
+| overlayClass | Custom overlay class | `String` | `` | - |
+| overlayStyle | Custom overlay style | `Object` | `` | - |
 | closeOnClickOverlay | Close popup when click overlay | `Boolean` | `true` | - |
 | transition | Transition | `String` | `popup-slide` | - |
 | preventScroll | Prevent background scroll | `Boolean` | `false` | - |