Flensburg: Seal Rescued from City Center Water Wheel
Here’s a breakdown of the HTML code you provided, focusing on the image and its responsive behavior:
Overall Structure
The code snippet represents a <picture> element, which is designed to provide different image sources based on screen size and browser support.This is a key technique for responsive images.
Key Components
* <picture> Element: The container for the responsive image setup.
* <source> Elements: These define different image sources based on media queries (screen size) and image type.
* type="image/webp": Specifies that the image is in WebP format (a modern image format that offers better compression). Browsers that support WebP will use these sources.
* media="(max-width: 40em)": This is a media query. It means that the image source within this <source> element will be used when the screen width is 40em or less. (1em is typically equal to the current font size, so 40em is roughly 640 pixels if the default font size is 16px).
* srcset="...": This attribute lists the different image URLs and their widths. The browser will choose the most appropriate image based on the screen size and pixel density. For example:
* https://images.ndr.de/image/ceda17f5-f52a-442d-89dc-797af9a2fa53/AAABkWssxo4/AAABmt42ZLw/4x3/seehundstation322.webp?width=256 256w means there’s an image at that URL that is 256 pixels wide.
* <img> Element: This is the fallback image. If the browser doesn’t support WebP or the media queries don’t match, it will display this image.
* src="...": The URL of the fallback image.
* alt="Seals in the Norddeich seal station.": Alternative text for accessibility (vital for screen readers and if the image fails to load).
* title="Seals in the Norddeich seal station. | NDR, Henning Kulbarsch": The title attribute provides additional information about the image when the user hovers over it.
* class="responsive": A class likely used by CSS to further control the image’s responsiveness (e.g., making it scale to fit its container).
* loading="lazy": This attribute tells the browser to only load the image when it’s near the viewport (the visible area of the screen). This improves page load performance.
how it Works (Responsive Behavior)
- Browser Check: The browser first checks if it supports WebP images.
- Media Query Evaluation: If WebP is supported, the browser evaluates the
media attributes of the<source>elements. - Image Selection:
* If the screen width is less than or equal to 40em, the browser will use the <source> element with media="(max-width: 40em)" and choose the most appropriate image from its srcset based on the screen’s pixel density.
* If the screen width is greater than 40em, the browser will use the first <source> element (without a media attribute) and choose the most appropriate image from its srcset.
- Fallback: If the browser doesn’t support webp, it will ignore the
<source>elements and display the image specified in the<img>tag.
In Summary
This code provides a responsive image that:
* Uses the modern WebP format when possible.
* Serves different image sizes based on screen size to optimize loading times and image quality.
* Provides a fallback image for browsers that don’t support WebP.
* Improves page load performance with lazy loading.
* Includes accessibility features (alt text).