fix bottom border for frozen columns

Author: mtrezza

src/components/BrowserCell/BrowserCell.react.js

@@ -638,6 +638,7 @@ export default class BrowserCell extends Component {
       style.left = this.props.stickyLeft;
       style.zIndex = 1;
       style.background = this.props.rowBackground;
+      style.borderBottom = '1px solid #e3e3ea';
     }
 
     return (

src/components/BrowserRow/BrowserRow.react.js

@@ -81,7 +81,13 @@ export default class BrowserRow extends Component {
           onMouseOver={() => onMouseOverRowCheckBox(obj.id)}
           style={
             freezeIndex >= 0
-              ? { position: 'sticky', left: 0, zIndex: 1, background: rowBackground }
+              ? {
+                  position: 'sticky',
+                  left: 0,
+                  zIndex: 1,
+                  background: rowBackground,
+                  borderBottom: '1px solid #e3e3ea',
+                }
               : {}
           }
         >