// addTest adds an arbitrary test callback to the test list.
//
// name must uniquely identify the test and heading must be non-empty.
func (t *tester) addTest(name, heading string, fn func(*distTest) error) {
	if t.testNames[name] {
		panic("duplicate registered test name " + name)
	}
	if heading == "" {
		panic("empty heading")
	}
	// Two simple checks for cases that would conflict with the fast path in registerTests.

.sub-title {
    margin:5px 0 0 0;
}
ul.contents-list {
    margin: 0 0 15px 0;
    padding: 0;
    list-style: none;
}
ul.contents-list li {
    font-size:0.93em;
}
/*
 * Styles for headings.
 */
body.class-declaration-page .summary h2,
body.class-declaration-page .details h2,
body.class-use-page h2,
body.module-declaration-page .block-list h2 {
    font-style: italic;
    padding:0;

	}

	.dark-mode {
		.site-header {
			-webkit-box-shadow: none;
			-moz-box-shadow: none;
			box-shadow: none;
			z-index: 2;
		}
	}

	/*
      Pushes the section headings to just below the top nav bar when a user
      navigates directly to section anchors.
     */
	#content h2[id],
	#content h3[id],
	#content h4[id],
	#content h5[id] {
		padding-top: 60px;
	}

The complete design specification can be found https://docs.google.com/document/d/1T_vM-Upa23aA21sanFTTLZa3j9xV6R32djJk6-muWzI/edit#heading=h.610fausqnpu6[here].

In implementing this spec, we have introduced the following breaking changes to the `ProblemSpec` interface: