Here's an example of a CSS style that you could use for an HTML advertisement:

.advertisement {

    background-color: #f2f2f2; /* Light gray background color */

    border: 1px solid #cccccc; /* Light gray border */

    padding: 20px; /* Padding around the content */

    text-align: center; /* Center align the text */

    max-width: 300px; /* Limit the width of the ad */

    margin: 0 auto; /* Center the ad on the page */


.advertisement img {

    width: 100%; /* Make the image fill the entire width of the ad */


.advertisement h2 {

    font-size: 24px; /* Large heading text */

    margin-bottom: 10px; /* Add some margin under the heading */

    color: #333; /* Dark gray heading color */

    text-transform: uppercase; /* Uppercase the heading text */

    letter-spacing: 2px; /* Add some space between letters */


.advertisement p {

    font-size: 18px; /* Medium-sized text */

    color: #555; /* Gray text color */

    line-height: 1.5; /* Add some space between lines */

    margin-bottom: 20px; /* Add some margin under the text */


.advertisement .button {

    background-color: #4CAF50; /* Green background color for the button */

    color: white; /* White text color for the button */

    padding: 12px 20px; /* Padding around the button */

    border: none; /* Remove the border */

    text-decoration: none; /* Remove the underline from the link */

    cursor: pointer; /* Change the cursor to a hand when hovering */

    margin-top: 20px; /* Add some margin above the button */


You can apply this CSS to an HTML structure like this one:

<div class="advertisement">

    <img src="your-image.jpg" alt="Ad image">

    <h2>Your Product</h2>

    <p>Lorem ipsum dolor sit amet, consectetur adipiscing elit. </p>

    <a href="#" class="button">Learn More</a>


This will create an advertisement block with a light gray background and a border, with an image on top, a heading, and a paragraph of text below it and a button at the end. The CSS code gives a specific design for the elements inside, like the text size, color, and spacing. Remember that you can always adjust this code to match your preferences and the design of your advertisement.