ademos

Hello.

You can use a conditional tag called “is_single” to only display your sidebar content on WordPress posts, but not on WordPress pages.

Add the following to your sidebar.php file.

<?php if (is_single() ) { ?>
<!-- Replace this comment with your sidebar content. -->
<?php } ?>

You can learn more about the “is_single” conditional tag here: http://codex.ww.wp.xz.cn/Function_Reference/is_single

In the case of the Twenty Fourteen theme, the white space you described on the left and right sides is caused by the “max-width” CSS property of the “entry-summary” class.

When the max-width is changed from the original 474px to 550px, most of the white space you described is reduced.

But keep in mind, if you shrink the width of your browser window you will see that changing the max-width property causes problems for small screen sizes. (In other words, the paragraphs have less of a margin at smaller screen sizes, which can reduce readability.)