I am using amp (Accelerated Mobile Pages Project) technology in a new project.
My concern is about amp-img tag for images. According to this documentation (https://github.com/ampproject/amphtml/blob/master/spec/amp-html-layout.md) you can use the attribut layout='responsive' for responsive purpose and in conjonction you can use srcset,media,sizes attributs also for responsive purpose.
Likewise, the documentation says that the image will take the space of its parent container.
I don't understand this logic. Why should we size the container to have the proper size of the image. If it works this way, it is very heavy to use.
Thank you in advance for your answers
The tricky part is having responsive elements render on the page without adversely affecting performance metrics or user experience.
Yes, you can easily get images to fit the screen without width and height but there are performance hits. I think that is why AMP does not allow responsive layout without width and height.
The browser must download the image first to get the dimensions of the image, then resize the image appropriately for the screen size, and finally reflow and repaint the page.
In AMP, the rendering path is optimized so that first the page is laid out, setting aside placeholders for the images based on the dimensions provided in amp-img (using those numbers to establish aspect ratio), then the resources are downloaded, and the page is painted. No reflow is required.
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I'm working with a responsive design and Lighthouse keeps telling me "Image elements do not have explicit width and height". I concluded that it means in the html, because my images have set dimensions in my css with different breakpoints.
Is there a best practice here to keep being responsive but make Lighthouse happy? It might be obvious, but as a student, I'm scratching my head here.
you are right that's actually the best practice and that is recommended for Web Vitals to enhance performance.
If you set height and width, the space required for the image is reserved when the page is loaded. However, without these attributes, the browser does not know the size of the image, and cannot reserve the appropriate space to it.
when you add img in general you should add in html width and height and I prefer to add values that I am adding in CSS or sometimes when I don't have values in CSS I'm doing inspect on the element and make the browser tell me width and height then I back to html and write them.
if you are interested in this topic (Performance) search about Web Vitals (Cumulative Layout Shift) you will find interesting topics
I have troubles regarding a slider I have on my website.
Currently it's a slider with the <img> element. Problem I encounter now is that on mobile the large images get loaded as well. Now I want to load specific (smaller) images for mobile so that my website is faster on these devices.
A solution I had was using the media queries in combination with CSS background image. This is perfect to use because I can load the images with CSS and thus can use media queries to select the image based on screen size.
But the problem is is that I want to add the images to the SEO, they are essential for my website and I read everywhere that if you have such images, you need to use the <img> element. So that the SEO can work and include these images in the content. Also I cannot add ALT tags to background-image.
Another solution is rendering two sliders, one for mobile and one for desktop, and hiding the slider you don't want to see. Problem I have with this solution is that both of the sliders need to render, thus decreasing performance.
Is there a solution that I'm missing here? In my understanding you cannot change images in a <img> element with CSS media queries.
You can use the picture element. As the Mozilla Developer Network says, "[This element] serves as a container for zero or more elements and one element to provide versions of an image for different display device scenarios". I think it does the trick. Here you are another good article that explains how to use this element to achieve the result you need with your responsive images.
The picture element is a really nice modern solution. But if you want something more cross-browser, consider an approach with JavaScript. My solution for some websites was using sets of images with regular suffixes, for example image.jmg, image-medium.jpg, image-small.jpg, and a script checking the screen resolution. In the HTML only small images are included, but if the script finds the screen is big enough, it updates their src with corresponding suffixes.
I was told that specifying inline width and height for all images will be good for SEO and also helps the site loads faster, like so:
<img src="http://www.example.com/images/free-size.jpg" width="200" height="400" alt="random image" />
Although I can still overwrite the inline setting using height:auto;.
So that images re-size properly when in different display platforms.
But just before I go ahead and doing this just want to reassure if these statements are true. Personally I feel dubious about fixing the inline dimension and overwriting using external CSS, just sound a bit hacky to me.....
I was told that specifying inline width and height for all images will
be good for SEO and also helps the site load faster.
Yes. This has traditionally been true (at least the "site loads faster" part).
By specifying the height and width attributes of an <img> the browser reserves a space matching those dimensions for the image while it continues parsing the rest of the HTML document. Then when the browser loads the image, the reserved space is waiting and there is no need to reflow the document.
Providing this sizing data results in a faster rendering process.
In contrast, if the width and height attributes are omitted, the browser will not know the size of the image until the download is complete, which forces the browser to reflow the document, slowing down the rendering process.
Now imagine a page with 50 images with no defined width and height attributes. The performance hit could be very noticeable.
The practice above represents the traditional view of image loading.
In contrast, some people are now saying that for responsive design the width and height attributes should be avoided.
Responsive Design does not normally use any width or height attributes
The majority of responsive websites do not use width or
height because they want the images to adapt to the screen size and by
using fixed width and height using <img> which would dampen user
experience and Google has declared this one of the most important
factors.
source: https://webmasters.stackexchange.com/a/68494
So there are arguments on both sides and the decision most likely depends on your individual case. As you make your decision here are some more details:
Specifying image dimensions to improve browser performance
Image width/height as an attribute or in CSS?
I was told that specifying inline width and height for all images will
be good for SEO and also helps the site loads faster.
No, it does help loading the site faster. It helps avoid flickering when rendering the page. If you want to load your images faster, make sure they have the same size as specified in the page and use a service like kraken.io to reduce the corresponding file size.
About SEO, it's improper image size and width for the screen size that can hurt your SEO. Google may consider you site as not user-friendly and/or not smartphone friendly.
If you do not tell the browser the size of your images then it must "build" the page not once, but twice (or more times depending on how many images you have on the page). It will build it once to display all the text, and then it will wait until an image is downloaded. When one image is downloaded the browser can now determine the size of the image and will rebuild the page to wrap the text around that image. This process will happen for every image on your page.
If you just specify the image dimensions, it will already know the size of the images and can use that information to shape the page. It won't have to rebuild the page a million times.
The best approach I think is to use the aspect ratio in css.
.img-container {
max-width: 500px;
aspect ratio: 2/1;
overflow:hidden;
}
The above css will reserve a container space for the image to load and prevent reflow.
I'm using rails and bootstrap and I'm using the bootstrap carousel on my landing page. I found that on the mobile view the carousel starts to look quite bad unless I make the pictures much higher than wide.
I wanted to use an if statement in my erb file to check the viewport size and render the appropriate image. I don't think using media queries in css is appropriate in this case as the image size determines the size of the carousel (not simply a background image).
Sorry if this is a newb question.
Erb is rendered server-side, which really has no notion of the viewport size, you would need to resort to using javascript in conjunction with your code, to make the adjustment.
This seems like a perfect case for media queries in the css. This is a much cleaner solution than muddling around with js.
You can, in the carousel, draw both of the images. Give all the wide images a distinct class (wide-image, for example) and all of the tall images a distinct class (tall-image, for example). Then, in the appropriate section in your css, simply set the undesirable image class to display none, which will effectively leave you with only the appropriate images displaying (and governing the size of the carousel).
I'm having a problem with a website I've built: whenever I view the site on a smaller monitor or when I resize the browser window, the content gets covered by the other divs. I need the content to be fully visible, no matter what size the browser is.
http://sophisticateddesign.nl/cfreport/overons.html
Also, on the homepage the text gets cut off a little bit on the bottom row when I resize the browser. I need this row to increase in height a bit, which apparently can't be achieved by simply increasing the divs' height.
http://sophisticateddesign.nl/cfreport/index.html
You should take a look at responsive web design. By using a fluid grid together with one or many media queries you can achieve what you're asking for.
Here's a good introduction if you'd like to get started. I can also highly recommend Ethan Marcotte's book about the subject!
The simplest way is not to define widths in pixels but using only width in %. You defined for example width: 960px; for <html> so if the browser window is less than 960px the whole content of this site won't be visible. You also defined the footer width and probably some more elements.
But the true is nowadays you should learn rather Responsive Web Design to create your page adjusting to device width. Many sites are being used by people on PC, laptops, tablets and mobile phones and you cannot create complex site to look nice on all those devices without using responsive design techniques.