Step 1: Adding the Site container

• Add a Group block before the Header block.
• Name this Group "Site".
• Set the content size under the Layout settings to 840.
• Place all blocks inside this new group.

Step 2: Adding the Content container

• Add a Group block after the Header.
• Name this Group "Content".
• Set the content size under the Layout settings to 750.
• Place the Query Loop block inside.