1.Universal selectors
eg:#target*{ }
2.Child selectors <
something immediately nested within something直接子女，不包括子孙
3.Adjacent Selector +
something immediately following something 直接跟在后面的第一个跟屁虫
CSS3：h1 ~ p { font-weight: bold }
will style all paragraphs after the top-level heading but if there
were any ps
preceding the h1,
these would not be affected.
【CSS3】Advanced3：Universal, Child, and Adjacent Selectors,布布扣,bubuko.com