This a page that (hopefully) in time will grow to cover the basic and simple HTML and CSS solutions.

Please add to your alternate solutions if you know a different way.

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making a <hr> horizontal rule smaller

hr {
  width: 75%;
  margin-left: auto;
  margin-right: auto;
}

Giving a <div> non scrolling background

#divName {
  padding-top: 50px;
  height: 500px;
  color: #fff;
  background-image: url("your_url.jpg");
  background-repeat: no-repeat;
  background-attachment: fixed;
  background-size: 100%;
}

try different values to see the how it affects the div
and over in the html
<div id="divName" class="container-fluid">

Center a horizontal list

http://csswizardry.com/2011/01/create-a-centred-horizontal-navigation/

Sections and Outlines of an HTML Document

https://developer.mozilla.org/en-US/docs/Web/Guide/HTML/Sections_and_Outlines_of_an_HTML5_document