class1 - Formatting and tag/validation fixes
class2 - Cleanup for typos, quotes, validating markup, style, extraneous tags, matching example code to actual markup.
class3 - Validation, quotes, indentation and other formatting fixes (esp. for large code blocks), extraneous tags
class4 - quotes, line breaks, validation, comments, indentation, and code sample formatting for space
Merge pull request #1 from EliseWei/common-updates

Structural updates