My content and layout cells change when I preview

S

SPCJOEMP

I am creating a website with a large amount of content. When I create a
layout and fill it with content, it all looks really nice in the design view.
When I click preview some of the cells are larger than I want them, some get
smaller and have empty spaces at the bottom. How can I make the preview look
the same as my design?
 
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