SEO之HTML代码优化一、 文档类型(DOCTYPE)XHTML1.0有三种DOCTYPE:1. 过渡型(Transitional)<!DOCTYPEhtml PUBLIC ”-//W3C//DTD XHTML 1.0 Transitional//EN” ”http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd”>2. 严格型(Strict)<!DOCTYPE html PUBLIC ”-//W3C//DTD XHTML 1.0 Strict//EN” ”http://www.w3.org/TR/xhtml1/DTD/xhtml1-strict.dtd”>3. 框架型(Frameset)<!DOCTYPE html PUBLIC ”-//W3C//DTD ...