Re: Always Problems with this custom inline Code!
You really need to learn how to look up these things for yourself. Firefox with its Firebug extension (or some other browsers' web developer tools) will let you find the styling that applies to any page element, and try new styling to see what works before you change actual files.
Just looking at "view source" in your browser will show you the name of the container just before your new content; use that in the style rule. If you want the same effect as the shipping page, just add the selector to the list at the beginning.
The Boutique page is a special case because there is not an id on the enclosing div. You can use a selector of #ezpagesHeading+div:
#shippingInfoMainContent, #ezpagesHeading+div {margin-top: 3em;}
Some of the other pages are also built very differently than the define page you were first asking about, and if you want this space for many or all pages, it will be better to change the approach and add margin below the <h1> instead of above the content.
h1 {margin-bottom: 3em;}
Of course you would need to remove the #shippingInfoMainContent margin so it doesn't double up. If this then causes undesired spacing in any pages, a rule can be made to exempt them from this general rule.
Re: Always Problems with this custom inline Code!
The h1 {margin-bottom: 3em;} worked perfectly to create the spacing for all pages. All of the errors have been eliminated, except for one I can't locate, and I think that one might be removed when I have the mega menu redone into a regular menu.
Thank you for your support.