Fluid width image html

Images

Documentation and examples for opting images into responsive behavior (so they never become larger than their parent elements) and add lightweight styles to them—all via classes.

Responsive images

Images in Bootstrap are made responsive with .img-fluid . max-width: 100%; and height: auto; are applied to the image so that it scales with the parent element.

Aligning images

Align images with the helper float classes or text alignment classes. block -level images can be centered using the .mx-auto margin utility class.

 class="text-center">  src=". " class="rounded" alt=". "> 

Picture

If you are using the element to specify multiple elements for a specific , make sure to add the .img-* classes to the and not to the tag.

  srcset=". " type="image/svg+xml">  src=". " class="img-fluid img-thumbnail" alt=". "> 

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CSS Responsive Image Tutorial: How to Make Images Responsive with CSS

Cem Eygi

The majority of today’s websites are responsive. And if you need to center and align image on those site, you need to learn how to make images fluid or responsive with CSS.

I posted a tutorial video that explains how to make a responsive website step by step a couple of weeks ago. In the video we made an image responsive. But in this post, I would like to give a bit more detail about how to make images responsive.

You will also learn some of the general problems that can occur when you’re trying to make images responsive – and I will try to explain how to solve them.

How to Make Images Responsive with CSS

Should I Use Relative or Absolute Units?

Making an image fluid, or responsive, is actually pretty simple. When you upload an image to your website, it has a default width and height. You can change them both with CSS.

To make an image responsive, you need to give a new value to its width property. Then the height of the image will adjust itself automatically.

The important thing to know is that you should always use relative units for the width property like percentage, rather than absolute ones like pixels.

For example, if you define a fixed width of 500px, your image won’t be responsive – because the unit is absolute.

That’s why you should instead assign a relative unit like 50%. This approach will make your images fluid and they will be able to resize themselves regardless of the screen size.

Should I Use Media Queries?

One of the questions I get asked the most is whether you should use media queries or not.

A media query is another important feature of CSS that helps make a website responsive. I won’t go into further details here but you can read my other post later to learn how to use media queries in more detail.

The answer to that question is: “it depends”. If you want your image to have different sizes from one device to another, then you will need to use media queries. Otherwise, you won’t.

Now for this example, your image has a 50% width for any kind of screen. But when you want to make it full-size for mobile devices you need to get help from media queries:

@media only screen and (max-width: 480px) < img < width: 100%; >>

So based on the media query rule, any device smaller than 480px will take the full size of the width of the screen.

You can also watch the video version of this post below:

Therefore, you can define a max-width property for the image and set it to 100%, which shrinks the image of 500px to the space of 360px. So you will be able to see the complete image on a smaller size screen.

The good thing is that, since you are using a relative unit, the image will be fluid in any device smaller than 500px.

Unfortunately, the screen size will get somewhat larger than 500px, but the image won’t because it has a default 500px of width. This approach will break the responsiveness of the image.

To fix this, you need to use the width property again, which makes the max-width property useless.

What about Heights?

Another common problem you may run across has to do with the height property. Normally, the height of an image automatically resizes itself, so you don’t need to assign a height property to your images (because it kinda breaks the image).

But in some cases, you might have to work with images that must have a fixed-height. So when you assign a fixed height to the image, it will still be responsive but it won’t look good.

Fortunately, there is another property that CSS offers to fix this problem…

Solution: The Object-Fit Property

To have more control over your images, CSS provides another property called object-fit. Let’s use the object-fit property and assign a value, which will make your image look better:

If needed, you can also use the object-position property (in addition to object-fit) to focus on a specific part of the image. Many people are not aware of the object-fit property, but it can be helpful to fix these kinds of problems.

I hope this post has helped you understand and solve your problems with responsive images. If you want to learn more about web development, feel free to check out my Youtube channel.

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CSS Fluid Image Techniques for Responsive Site Design

• CSS @media queries
• Fluid images and video
• Fluid layout techniques, including flexbox, percentage units, and (in the near future) CSS Grids.
• JavaScript, often triggered by window.matchMedia
• Server-side solutions
• SVG to create resolution-free images

A responsive site may utilize one, some, or all of these technologies, depending on the intentions of its designers. I’ve covered the basics of media queries in past articles; now it’s time to look at fluid images, a technique first suggested by Ethan Marcotte.

Web page text is fluid by default: as the browser window narrows, text reflows to occupy the remaining space. Images are not naturally fluid: they remain the same size and orientation at all configurations of the viewport, and will be cropped if they become too large for their container. This creates a conundrum when displaying images in a mobile browser: because they remain at their native size, images may be cut off or displayed out-of-scale compared to the surrounding text content as the browser narrows.

Simple Fluid Images

One way around this is to size images in relative units, rather than absolute pixel dimensions. The most common relative solution is to set the max-width of the image at 100% :

Images with this CSS will display at their native dimension so long as there is enough room in the HTML container to do so; as the browser window narrows, the images will scale to fit, as you can see in the illustration above.

• A large image (over ~ 420 pixels wide) will increasingly dominate the document as the viewport shrinks down, as its native size is greater than the width of most smartphones. Scaling means that the image won’t be cut off, but it may be large relative to text at small viewport sizes.
• The initial layout and setup of the document is affected: because you are not setting the image’s height and width explicitly in the CSS, the browser cannot reserve any space for the image in the page. This will often cause the layout to “pop” when the user visits the page for the first time, as fluid images are loaded and forced to fit into their newly determined size.
• Unless the image is already the full width of its container, this approach does not work well for HiDPI/Retina images: the image’s “actual size” will be shown as twice the width that you want it to be.

The basic max-width fluid image approach is a very good approach for article header and “hero” images, but for illustrations in body text, a more subtle approach is often required.

A Better Fluid Image Solution

A better, albeit more complex approach to fluid images is to measure the width of the image as a percentage of the overall width of the page.

For example, let’s say you had an image that had a natural size of 500px × 300px in a 1200px wide document. Below 1200px, the document will be fluid. The calculation of how much width the image takes up as a percentage of the document is easy:

We can plug this number in as the width for the image; often this would be done inline, as each image will often be a different dimension:

With this approach, the image will always remain in scale with the rest of the text:

This accommodates Retina pixel-doubled images, but can run into issues at extremes of large or small viewport sizes, when the image might appear too big or small relative to the text. To get around this, we can place a max and/or min width on the image in pixels as upper and lower limits:

The type of approach you use will depend on both the kind of image and the overall design of the site; there is also the possibility of transitioning the flexible images between breakpoints with a hybrid technique that utilizes media queries: we’ll look at that in the next article.

Improving Browser Performance

Specifying only the width of images may cause a doubling or tripling of the cycles that many browsers must process to layout the new, resized page. While each of these cycles typically take less than a millisecond, they stack up, especially if there are multiple scalable elements on the page. Addressing height in the same declaration can reduce this issue:

Finally, browsers are not always well-optimized to resizing images at quality. Chrome and Safari in particular can suffer from a slight blurriness to bitmap images, especially as they are scaled down. A setting in CSS can help in this regard:

It should be noted that the difference this makes can vary between screens and platforms, so it is advisable to test its benefits before pushing to production.

Enjoy this piece? I invite you to follow me at twitter.com/dudleystorey to learn more.

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