1. What is CSS + How to Write It

CSS controls how HTML looks. Without CSS, every page looks the same.

Three ways to write CSS:

Inline — directly on the element.

<h1 style="color: red;">Hello</h1>

Internal — inside a <style> tag in <head>.

<head>
  <style>
    h1 {
      color: red;
    }
  </style>
</head>

External — a separate .css file linked to your HTML.

<head>
  <link rel="stylesheet" href="style.css">
</head>

h1 {
  color: red;
}

CSS rule structure