Even though browsers do start with inconsistent defaults, it’s possible to override them. In the hierarchy of CSS specificity, the browser’s default stylesheet is at the very bottom. Any inline or externally defined styles will override browser defaults.

With the ability to override those default styles, you’re able to explicitly define a new set of your own default rendering styles. Instead of allowing each browser to decide how much space should be above and below block level elements, for example, you have the opportunity to preemptively dictate styling that renders identically across all browsers.

In other words, there’s nothing preventing you from resetting all of the default styling for HTML elements to a predictable baseline style. In fact, doing so will almost entirely negate the cross-browser variances in default styling.

This technique is called a CSS reset.