<!DOCTYPE html> is the standard mode of w3c. If it is not marked, the browser will parse and render the page in its own way, so different styles will be displayed in different browsers. Once you mark it, the browser will have to parse and render the page in accordance with W3C standards. In this way, your page will appear the same in all browsers
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<!DOCTYPE html> is the standard mode of w3c. If it is not marked, the browser will parse and render the page in its own way, so different styles will be displayed in different browsers. Once you mark it, the browser will have to parse and render the page in accordance with W3C standards. In this way, your page will appear the same in all browsers