Add space

margins

<!DOCTYPE html>
<html>
<head>
    <title>Spacing Example</title>
    <style>
        .spacer {
            margin-bottom: 20px;
        }
    </style>
</head>
<body>

<div class="spacer"></div>
<p>This is a paragraph with some space below it.</p>

</body>
</html>

padding

<!DOCTYPE html>
<html>
<head>
    <title>Spacing Example</title>
    <style>
        p {
            padding-bottom: 20px;
        }
    </style>
</head>
<body>

<p>This is a paragraph with some space below it.</p>

</body>
</html>

Add favicon

<!DOCTYPE html>
<html>
<head>
    <title>Page Title</title>
    <link rel="icon" href="favicon.ico" type="image/x-icon">
</head>
<body>

<!-- Your HTML content here -->

</body>
</html>

Add css

<style>

<!DOCTYPE html>
<html>
<head>
    <title>CSS Example</title>
    <style>
        body {
            background-color: #f0f0f0;
            font-family: Arial, sans-serif;
        }
        h1 {
            color: blue;
        }
        p {
            font-size: 16px;
        }
    </style>
</head>
<body>

<!-- Your HTML content here -->

</body>
</html>

external CSS file

<!DOCTYPE html>
<html>
<head>
    <title>CSS Example</title>
    <link rel="stylesheet" type="text/css" href="styles.css">
</head>
<body>

<!-- Your HTML content here -->

</body>
</html>

Add video

<!DOCTYPE html>
<html>
<head>
    <title>Video Example</title>
</head>
<body>

<video width="640" height="360" controls>
  <source src="path_to_your_video.mp4" type="video/mp4">
  Your browser does not support the video tag.
</video>

</body>
</html>

Add a background image

<!DOCTYPE html>
<html>
<head>
    <title>Background Image Example</title>
    <style>
        body {
            background-image: url("path_to_your_image.jpg");
            background-size: cover;
        }
    </style>
</head>
<body>

<!-- Your content here -->

</body>
</html>