[bugfix] Popup modal display error

packages/vant-css/src/common/animation.css

@@ -10,6 +10,15 @@
   }
 }
 
+@keyframes van-fade-in {
+  from {
+    opacity: 0;
+  }
+  to {
+    opacity: 1;
+  }
+}
+
 .van-slide-bottom {
   &-enter-active {
     animation: van-slide-bottom-enter .3s both ease;

packages/vant-css/src/popup.css

@@ -8,7 +8,11 @@
     top: 0;
     left: 0;
     background-color: rgba(0, 0, 0, 0.7);
-    transition: .5s ease-out;
+    animation: van-fade-in .3s both;
+  }
+
+  &-overflow-hidden {
+    overflow: hidden !important;
   }
 
   &-popup {