how to style a heading in html code example

Example 1: html headings

<h1>I'm the biggest heading</h1>
<h2>I'm smaller than h1</h2>
<h3>I'm smaller than h2</h3>
<h4>I'm smaller than h3</h4>
<h5>I'm smaller than h4</h5>
<h6>I'm the smallest heading</h6>

Example 2: html h1 size

h1  =>    32px    (2em)
h2  =>    24px  (1.5em)
h3  =>  20.8px  (1.3em)
h4  =>    16px    (1em)
h5  =>  12.8px  (0.8em)
h6  =>  11.2px  (0.7em)

Example 3: headers htnk

<h1>Header 1</h1>
<h2>Header 2</h2>
<h3>Header 3</h3>
<h4>Header 4</h4>
<h5>Header 5</h5>
<h6>Header 6</h6>
<p>p tag</p>