Fix sticky behavior in Safari (#525)

Author: Marc-Andre-Rivet

CHANGELOG.md

@@ -36,6 +36,9 @@ between two tables within the same tab.
 reset the filter for the affected column(s)
 
 ### Fixed
+[#259](https://github.com/plotly/dash-table/issues/259)
+- Fixed columns `sticky` on Safari
+
 [#491](https://github.com/plotly/dash-table/issues/491)
 - Fixed inconsistent behaviors when editing cell headers
 

src/dash-table/components/Table/Table.less

@@ -257,6 +257,7 @@
                 flex: 0 0 auto;
                 left: 0;
                 position: sticky;
+                position:-webkit-sticky;
                 z-index: 400;
             }
 
@@ -436,6 +437,10 @@
         background-color: rgb(250, 250, 250);
     }
 
+    .dash-spreadsheet-inner td {
+        background-color: white;
+    }
+
     .sort {
         cursor: pointer;
         float: left;