How I Solved the Full-Width Layout Challenge Using CSS

How I Made Inner Sections Span Full Width Across All Devices (with a Single CSS Solution)

By Sagar P, Frontend Developer at Acquaint Softtech

As a frontend developer at Acquaint Softtech, I often work on responsive hero sections and complex layouts for enterprise websites and SaaS platforms. One challenge I faced was making an inner container element, such as a hero image, stretch across the full width of the screen on every device without breaking the layout.

In this post, I will walk you through the problem, the first approaches I tried, and the final CSS solution that works consistently on desktop, tablet, and mobile.

Introduction

In this scenario, I needed to reposition a specific image element from inside the container to slightly outside its bounds, while keeping it perfectly centered within the hero section across all screen sizes.

To achieve a consistent design across desktop, tablet, and mobile views, I focused on managing the container layout, including its border lines, to maintain visual harmony. I chose a CSS Grid structure to organize the inner content section by section, which made layout management more intuitive.

Basic foundation

HTML:

<div class="container mx-auto mt-40">
  <div class="grid grid-cols-5">
    <div class="col-span-3 h-50 bg-red-100">
    </div>
    <div class="col-span-2 h-50 bg-yellow-100 border-l-2 border-blue-300">
    </div>
  </div>
</div>

<div class="border-t-2 border-blue-300">
  <div class="container mx-auto">
    <div class="grid grid-cols-5">
      <div class="col-span-3 h-50 bg-red-100">
      </div>
      <div class="col-span-2 h-50 bg-yellow-100 border-l-2 border-blue-300">
      </div>
    </div>
  </div>
</div>

However, Grid alone wasn’t enough. The design also required precise spacing on both the left and right sides, with border lines aligning across rows. Additionally, the image needed to fully touch the left edge of the screen on every viewport without breaking the layout.

To solve this, I experimented with various CSS techniques to consistently left-align the image while preserving the overall structure.

Layout Foundation

HTML:

<div class="container mx-auto mt-40">
  <div class="grid grid-cols-5">
    <div class="col-span-3 h-50 bg-red-100">
      <h1 class="px-4 py-10 text-4xl font-bold">Default Title</h1>
    </div>
    <div class="col-span-2 h-50 border-l-2 border-blue-300 bg-yellow-100"></div>
  </div>
</div>

<div class="border-t-2 border-blue-300">
  <div class="container mx-auto">
    <div class="grid grid-cols-5">
      <div class="col-span-3 bg-red-100">
        <img class="w-full h-full object-cover object-center" 
             src="https://images.unsplash.com/photo-1748229491574-a612c1062868?ixlib=rb-4.1.0&ixid=M3wxMjA3fDB8MHxwaG90by1wYWdlfHx8fGVufDB8fHx8fA%3D%3D" 
             alt="">
      </div>

      <div class="col-span-2 flex flex-col justify-between border-l-2 border-blue-300 bg-yellow-100 p-4">
        <label class="mb-0 font-medium">Default Sub Heading</label>
        <div class="flex flex-col">
          <h2 class="mb-4 text-lg">Default Content</h2>
          <button type="button" 
                  class="min-w-none me-2 mb-2 w-auto l:max-w-none rounded-lg bg-blue-700 px-5 py-2.5 text-sm font-medium text-white hover:bg-blue-800 focus:ring-4 focus:ring-blue-300 focus:outline-none dark:bg-blue-600 dark:hover:bg-blue-700 dark:focus:ring-blue-800">
            Default
          </button>
        </div>
      </div>
    </div>
  </div>
</div>

The first step was building the foundational layout to support these adjustments. For this, I defined the parent container with a fixed maximum width and padding to ensure content such as headings, text, and buttons stayed aligned.

Inside this container, I divided the hero section into grid rows. Each row was responsible for handling one type of content (for example: title in the first row, image in the second row, and supporting text in the third row).

This grid-based approach made it easy to handle alignment, spacing, and responsive scaling. It also gave me the flexibility to experiment with individual rows without affecting the rest of the layout.

At this stage, the structure was clean and stable, but I needed to go further to solve the full-width image problem.

First Attempt

HTML:

<div class="container mx-auto mt-40">
  <div class="grid grid-cols-5">
    <div class="col-span-3 h-50 bg-red-100">
      <h1 class="px-4 py-10 text-4xl font-bold">Default Title</h1>
    </div>
    <div class="col-span-2 h-50 border-l-2 border-blue-300 bg-yellow-100"></div>
  </div>
</div>

<div class="border-t-2 border-blue-300">
  <div class="container mx-auto">
    <div class="grid grid-cols-5">
      <div class="col-span-3 bg-red-100 -ml-[calc(1280px+((100%-1280px)/2)*-1)]">
        <img class="w-full h-full object-cover object-center" 
             src="https://images.unsplash.com/photo-1748229491574-a612c1062868?ixlib=rb-4.1.0&ixid=M3wxMjA3fDB8MHxwaG90by1wYWdlfHx8fGVufDB8fHx8fA%3D%3D" 
             alt="">
      </div>

      <div class="col-span-2 flex flex-col justify-between border-l-2 border-blue-300 bg-yellow-100 p-4">
        <label class="mb-0 font-medium">Default Sub Heading</label>
        <div class="flex flex-col">
          <h2 class="mb-4 text-lg">Default Content</h2>
          <button type="button" 
                  class="min-w-none me-2 mb-2 w-auto l:max-w-none rounded-lg bg-blue-700 px-5 py-2.5 text-sm font-medium text-white hover:bg-blue-800 focus:ring-4 focus:ring-blue-300 focus:outline-none dark:bg-blue-600 dark:hover:bg-blue-700 dark:focus:ring-blue-800">
            Default
          </button>
        </div>
      </div>
    </div>
  </div>
</div>

After that, I organized all the necessary inner content and elements, placing them systematically within each grid box. At this stage, the structural layout was complete, and the codebase was ready with the finalized output.

I was working on repositioning the second-row image so that it aligned flush with the left edge of the screen, without disrupting the layout across devices, from tablets to large desktops.

My initial idea was to shift an inner container element outside its parent using CSS margin.

Second Attempt

HTML:

<div class="container mx-auto mt-40">
  <div class="grid grid-cols-5">
    <div class="col-span-3 h-50 bg-red-100">
      <h1 class="px-4 py-10 text-4xl font-bold">Default Title</h1>
    </div>
    <div class="col-span-2 h-50 border-l-2 border-blue-300 bg-yellow-100"></div>
  </div>
</div>

<div class="border-t-2 border-blue-300">
  <div class="container mx-auto">
    <div class="grid grid-cols-5">
      <div class="col-span-3 bg-red-100 ml-[calc(-100vw/2+100%/2)]">
        <img class="w-full h-full object-cover object-center" 
             src="https://images.unsplash.com/photo-1748229491574-a612c1062868?ixlib=rb-4.1.0&ixid=M3wxMjA3fDB8MHxwaG90by1wYWdlfHx8fGVufDB8fHx8fA%3D%3D" 
             alt="">
      </div>

      <div class="col-span-2 flex flex-col justify-between border-l-2 border-blue-300 bg-yellow-100 p-4">
        <label class="mb-0 font-medium">Default Sub Heading</label>
        <div class="flex flex-col">
          <h2 class="mb-4 text-lg">Default Content</h2>
          <button type="button" 
                  class="min-w-none me-2 mb-2 w-auto l:max-w-none rounded-lg bg-blue-700 px-5 py-2.5 text-sm font-medium text-white hover:bg-blue-800 focus:ring-4 focus:ring-blue-300 focus:outline-none dark:bg-blue-600 dark:hover:bg-blue-700 dark:focus:ring-blue-800">
            Default
          </button>
        </div>
      </div>
    </div>
  </div>
</div>

In my first attempt, I applied a negative margin-left based on a formula tied to the container’s max width. This approach looked acceptable on larger screens but quickly broke down when tested on smaller devices.

On desktop, the image stretched further than intended, while on mobile it became cropped and looked uneven. The reliance on container width made this method unreliable because containers behave differently depending on the device breakpoint.

What I learned from this experiment was that negative margins are often a “quick fix” but not a sustainable solution for responsive design. They can create more problems than they solve, especially when the design needs to work consistently across different viewports.

Viewport-Based Approach

I noticed that applying a negative margin-left of around 15% helped slightly, but the output still wasn’t quite what I expected.

So, I explored another approach. Instead of relying on the container’s width and percentage-based sizing, I switched to using the viewport width (vw) to structure the layout more effectively.

This solution worked partially — about 60% of the output matched my expectations. However, if you looked closely, the image still appeared cropped on the left side of the screen.

Refining the Image

To address this, I fine-tuned the image positioning further. In my codebase, I had already applied:

CSS:

object-fit: cover;  
object-position: center;  

aspect-ratio: 16/9;

These helped, but they didn’t fully resolve the issue.

So, I adjusted the image’s width to auto and set its height to fill the screen based on its aspect ratio. The aspect-ratio property in CSS ensures the image maintains correct proportions while adapting smoothly to different viewport dimensions.

This displayed the image in full view without cropping. At this point, I had almost achieved the desired result for the hero section.

Final Solution

HTML:

<div class="container mx-auto mt-10">
  <div class="grid grid-cols-5">
    <div class="col-span-3 h-50 bg-red-100">
      <h1 class="px-4 py-10 text-4xl font-bold">Default Title</h1>
    </div>
    <div class="col-span-2 h-50 border-l-2 border-blue-300 bg-yellow-100"></div>
  </div>
</div>

<div class="border-t-2 border-blue-300 mb-10">
  <div class="container mx-auto">
    <div class="grid grid-cols-5">
      <div class="col-span-3 bg-red-100 ml-[calc(-100vw/2+100%/2)] aspect-video">
        <img class="w-auto h-full object-cover object-center ml-auto" 
             src="https://images.unsplash.com/photo-1748229491574-a612c1062868?ixlib=rb-4.1.0&ixid=M3wxMjA3fDB8MHxwaG90by1wYWdlfHx8fGVufDB8fHx8fA%3D%3D" 
             alt="">
      </div>

      <div class="col-span-2 flex flex-col justify-between border-l-2 border-blue-300 bg-yellow-100 p-4">
        <label class="mb-0 font-medium">Default Sub Heading</label>
        <div class="flex flex-col">
          <h2 class="mb-4 text-lg">Default Content</h2>
          <button type="button" 
                  class="min-w-none me-2 mb-2 w-auto l:max-w-none rounded-lg bg-blue-700 px-5 py-2.5 text-sm font-medium text-white hover:bg-blue-800 focus:ring-4 focus:ring-blue-300 focus:outline-none dark:bg-blue-600 dark:hover:bg-blue-700 dark:focus:ring-blue-800">
            Default
          </button>
        </div>
      </div>
    </div>
  </div>
</div>

I achieved 99% of the expected output by applying a different refined solution. The only remaining adjustment was the image height, which I modified by fine-tuning the aspect ratio to make it adapt seamlessly across all viewports.

This final update delivered the full result I wanted.

Conclusion

This experiment taught me a few important lessons about CSS layout design:

• Negative margins are tempting but usually break responsiveness.

• Viewport units are powerful, especially when you want elements to span the full width of the screen.

• Properties like object-fit, object-position, and aspect-ratio are essential tools for controlling how images behave inside layouts.

By combining these techniques, I arrived at a single CSS solution that works consistently across desktop, tablet, and mobile devices. It keeps the layout clean, reusable, and scalable for future projects.

If you are struggling with making inner sections full width, remember that the best solution is often a combination of small adjustments rather than one single property.

Build Responsive Layouts with Acquaint Softtech

Hire skilled frontend and full-stack developers from $20/hour who deliver scalable, pixel-perfect, and responsive designs using modern CSS and frameworks.

Start in 48 Hours