add space to each div tab of grid edit

src/client/js/components/PageEditor/GridEditorUtil.js

@@ -130,8 +130,9 @@ class GridEditorUtil {
 
   convertRatiosAndSizeToHTML(ratioNumbers, responsiveSize) {
     const cols = ratioNumbers.map((ratioNumber, i) => {
+      const spaceTab = '    ';
       const className = `col${responsiveSize !== 'xs' ? `-${responsiveSize}` : ''}-${ratioNumber} bsGrid${i + 1}`;
-      return `<div class="${className}"></div>`;
+      return `${spaceTab}${spaceTab}<div class="${className}"></div>`;
     });
     return cols.join('\n');
   }