优化移动端样式

Change-Id: I0f7b9c15514d13125e3c1a20e34062fd9e9d3fd3

examples/mobile.tsx

@@ -78,7 +78,8 @@ class AMISComponent extends React.Component {
           copy: content => {
             copy(content);
             toast.success('内容已复制到粘贴板');
-          }
+          },
+          affixOffsetTop: 0
         })}
       </div>
     ) : null;

scss/components/_table.scss

@@ -463,6 +463,7 @@
     > tbody > tr > td.#{$ns}Table-checkCell {
       border-right: 0;
       width: px2rem(1px);
+      padding-right: $TableCell-paddingX;
 
       .#{$ns}Checkbox {
         margin: 0;