fix(MdButton): fab-bottom-center style (#1724)

VdustR · web-flow · commit d1b296e5d50b · 2018-05-13T19:30:49.000+08:00
fix #1722
diff --git a/src/components/MdButton/MdButton.vue b/src/components/MdButton/MdButton.vue
@@ -340,7 +340,7 @@
     }
 
     &.md-fab-bottom-center {
-      top: 24px;
+      bottom: 24px;
     }
 
     &.md-fab-top-right,
