A CSS rule consists of a selector and a declaration block.
selector {
property: value;
}
p {
color: blue;
}
This is a paragraph.
.class-name {
font-size: 16px;
}
This is a paragraph with class.
#id-name {
margin: 10px;
}
This is a paragraph with ID.
Apply the same styles to multiple elements:
h1, h2, h3 {
color: red;
}