Flix: Creating a Scrollable Area

Topics Covered in This HTML & CSS Tutorial:

Creating a Horizontal Scrollable Area

Exercise Preview

Photos courtesy of istockphoto, unizyne, Image #19302441, Marcello Bortolino, Image #17472015, Sergey Kashkin, Image #318828, Sveta Demidoff, Image #2712135.

Exercise Overview

In this exercise, you'll master one of the most essential UI patterns in modern web development: creating smooth, performant horizontal scrolling areas. This technique powers everything from Netflix-style carousels to product galleries on e-commerce sites. Beyond the basic implementation, you'll also learn to optimize the experience for iOS devices by adding the native scroll bounce behavior users expect—a crucial detail that separates professional implementations from amateur ones.

Styling the Horizontal Scroll Area

Let's dive into building this scrollable interface step by step, starting with the foundational setup and progressing to the advanced optimization techniques.

1. We'll be switching to a new folder of prepared files for this exercise. In your code editor, close all open files to avoid confusion and maintain a clean workspace.
2. For this exercise, we'll be working with the Flix Scrollable Area folder located in Desktop > Class Files > Advanced HTML CSS Class. Open that folder in your code editor if it supports folder-based workflows (like Visual Studio Code, Sublime Text, or similar modern editors).
3. Open index.html from the Flix Scrollable Area folder to examine our starting markup structure.

4. Preview index.html in a browser to see the current state.

   Since we're implementing a mobile-first approach—the industry standard for responsive design in 2026—make your browser window narrow to simulate a mobile device viewport. You can also use your browser's developer tools to toggle device simulation for more accurate testing.

   Notice the movie posters are currently stacked vertically. Our design specification calls for these posters to display in a single horizontal line with smooth scrolling functionality. On smaller viewports, users should be able to scroll horizontally when all posters don't fit within the available screen real estate. First, let's transform the vertical stack into a horizontal layout.

5. Return to your code editor to begin implementing the layout changes.
6. Open main.css from the css folder (located within the Flix Scrollable Area folder) to access our stylesheet.
7. The movie posters are contained within an unordered list that has a movies class applied to it. Locate the .movies li rule, which targets the individual list items in our movies container and currently defines their dimensions and spacing properties.

8. Add the following code to transform the vertical stack into a horizontal layout:

   .movies li {
       display: inline-block;
       width: 99px;
       margin-right: 11px;
   }

   The inline-block display property is key here—it allows elements to sit side-by-side while still respecting width and margin properties, unlike pure inline elements.

9. Save the file, then reload the page in your browser to see the transformation.

   The posters now display horizontally, but there's a critical issue: when you narrow the browser window, the movie posters wrap to additional lines. This breaks our intended user experience—we need to prevent this wrapping behavior entirely.

10. Switch back to your code editor to address the wrapping issue.

11. Directly above the .movies li rule, locate the .movies rule that targets our container element. Add the following property:

    .movies {
       background-color: #fff;
       padding: 15px;
       margin: 0;
       white-space: nowrap;
    }

    The white-space: nowrap property forces all content to remain on a single line, preventing the natural wrapping behavior of inline-block elements.

12. Save the file, reload the page in your browser, and test the behavior:

    • Narrow the browser window to confirm that movie posters no longer wrap to multiple lines—excellent!

    • However, we've introduced a new problem: the posters now extend beyond the viewport width, causing the entire page to scroll horizontally. This creates a poor user experience because users lose context of the page structure. We need to isolate the scrolling behavior to just the poster section.

13. Return to your code editor to implement the final crucial piece of the puzzle.

14. Add the following property to the .movies rule to create contained scrolling:

    .movies {
       background-color: #fff;
       padding: 15px;
       margin: 0;
       white-space: nowrap;
       overflow-X: auto;
    }

    Technical note: The overflow-X property specifically controls horizontal overflow behavior along the X-axis. The auto value intelligently adds scrollbars only when content exceeds the container's width—no unnecessary scrollbars cluttering the interface when they're not needed.

15. Save the file, then reload the page for final testing.

    Perfect! Now only the poster area scrolls, maintaining the page's overall layout integrity. This implementation works seamlessly across desktop browsers (which typically display visible scrollbars) and mobile browsers (which usually hide scrollbars, relying on touch-based swiping gestures for navigation).

Optional Bonus: Removing Extra Margin

Now let's address a common layout refinement that separates polished implementations from basic ones. Currently, each movie poster has 11px of right margin, which creates appropriate spacing between posters but also adds unwanted extra space after the final poster. Since our container already has padding, this creates visual imbalance. Here's how to eliminate that excess space with precision targeting:

1. Switch back to your code editor to implement this refinement.

2. Below the .movies li rule, add this targeted selector:

   .movies li:last-child {
      margin-right: 0;
   }

   This CSS pseudo-selector specifically targets only the final list item, removing its right margin while preserving the spacing between all other posters.

3. Save the file, then reload the page to see the improvement.

4. Scroll to the rightmost end of the poster collection and observe how the margin after the last poster now matches the consistent spacing throughout the rest of the interface—a subtle but important detail for professional-grade implementations.