w3school's chapter on attribute selectors states that:
IE7 and IE8 support attribute selectors only if a !DOCTYPE is specified.
IE7 and IE8 don't recognize the HTML5 doctype, right?
So, does this mean that IE7 and IE8 won't recognize my attribute selectors if I use the HTML5 doctype?
Your attribute selectors will still work.
Although IE7 and IE8 don't understand that the HTML5 doctype means the document is HTML5, it by itself is still a doctype declaration, and they understand the syntax in general, so they will still render your page in standards mode.
As long as you have some kind of doctype declaration in place, IE will (do its best to) render your page in standards mode, including supporting whatever CSS it supports.
Note they aren't stating the HTML5 doctype but state it requires a doctype, though poorly worded. All new web pages are required to have a doctype so the point is moot. Use the HTML5 doctype because it puts all browsers into standards mode where you want to be.
As far as CSS goes, it's more important to know which properties the browser supports in the first place.
来源：https://stackoverflow.com/questions/7801470/ie-support-for-attribute-selectors-with-html5-doctype