Merge pull request 'feat: fixing the index problem' (#36) from fix-2020-07 into develop

Reviewed-by: palytoxin <sxty32@126.com>

web_src/less/_base.less

@@ -1296,3 +1296,8 @@ i.icon.centerlock {
     height: 1em !important;
     vertical-align: middle !important;
 }
+
+.ui.grid>.column:not(.row),
+.ui.grid>.row>.column {
+    z-index: 0,
+}