Rulesets #

A ruleset consists of a selector (or a group of selectors) paired with a declaration block.

A declaration block {} contains one or more declarations.

A declaration Property: Value; sets a value for a property.

Selectors, properties, and values are case-insensitive.

* {
  box-sizing: border-box;
}

h1,
h2 {
  font-size: 30px;
}