This is how your browser styles markup. All content displayed between the two dashed lines is styled only with your browser’s default CSS. As you can see, browsers add stuff like padding and margins to different markup elements, such as heading, paragraph, and list tags. These default browser styles are sometimes useful, but can interfere with layout, typography, and other aspects of your site’s design. Using a CSS Reset, you can neutralize the many disparate browser defaults and establish a clean foundation for applying CSS consistently across browsers. There are many CSS Resets available, including everything from very basic resets to comprehensive resets consisting of many styles.
Remove unused CSS - CSS Optimizer How it's working A web crawler follows the links of your site. On each page, we retrieve the CSS files and list the selectors. The selectors are tested on the html page. If the selector matches an element, it is marked as used.