To create responsive images using CSS, it can be mainly achieved through the following methods: 1. Use max-width:100% and height:auto to allow the image to adapt to the container width while maintaining the proportion; 2. Use HTML's srcset and sizes attributes to intelligently load the image sources adapted to different screens; 3. Use object-fit and object-position to control image cropping and focus display. Together, these methods ensure that the images are presented clearly and beautifully on different devices.

Native lazy loading is a built-in browser function that enables lazy loading of pictures by adding loading="lazy" attribute to the tag. 1. It does not require JavaScript or third-party libraries, and is used directly in HTML; 2. It is suitable for pictures that are not displayed on the first screen below the page, picture gallery scrolling add-ons and large picture resources; 3. It is not suitable for pictures with first screen or display:none; 4. When using it, a suitable placeholder should be set to avoid layout jitter; 5. It should optimize responsive image loading in combination with srcset and sizes attributes; 6. Compatibility issues need to be considered. Some old browsers do not support it. They can be used through feature detection and combined with JavaScript solutions.

The main difference is that textarea supports multiple lines of text input, while inputtext is only available in a single line. 1. Use inputtype="text" to be suitable for short and single-line user input, such as username, email address, etc., and can set maxlength to limit the number of characters. The browser provides automatic filling function, making it easier to uniformly style across browsers; 2. Use textarea for scenarios that require multiple lines of input, such as comment boxes, feedback forms, support line breaks and paragraphs, and can control the size through CSS or disable the adjustment function. Both support form features such as placeholders and required fills, but textarea defines the size through rows and cols, and input uses the size attribute.

When writing web content, you need to pay attention to the title and paragraph structure to improve the reading experience and SEO effect. 1. The title level should be clear. A page should only use one h1 as the main title, h2 as the title of the big section, and h3 subdivides the subsections to avoid multiple h1, skip grades or keyword piles up; 2. The paragraph should be controlled in three to four lines, and the key points should be directly mentioned at the beginning, and if necessary, use the ul list to enhance readability; 3. Appropriately use the subtitles of h2 and h3 to guide readers' attention, facilitate information search and optimize search engine recognition.

It is a block-level element, used to divide large block content areas; it is an inline element, suitable for wrapping small segments of text or content fragments. The specific differences are as follows: 1. Exclusively occupy a row, width and height, inner and outer margins can be set, which are often used in layout structures such as headers, sidebars, etc.; 2. Do not wrap lines, only occupy the content width, and are used for local style control such as discoloration, bolding, etc.; 3. In terms of usage scenarios, it is suitable for the layout and structure organization of the overall area, and is used for small-scale style adjustments that do not affect the overall layout; 4. When nesting, it can contain any elements, and block-level elements should not be nested inside.

The key to implementing responsive images in srcset is to understand the syntax and browser selection mechanism. 1. Basic structure: Provide multiple image versions through srcset, and use w descriptors to indicate the width, such as 320w and 480w; 2. Use sizes attribute to define the display size of the image under different screen widths, such as 100vw and 50vw; 3. Use x descriptors to provide high-definition images for high-resolution screens, such as 1x and 2x; 4. The actual suggestions include manually or tools to generate multi-size images, avoiding too many options affecting performance, and setting the alt attribute to ensure accessibility.

To correctly set the character encoding of the HTML document to UTF-8, you need to follow three steps: 1. Add at the top of the HTML5 part; 2. Configure the response header Content-Type: text/html; charset=UTF-8, if Apache uses AddDefaultCharsetUTF-8, Nginx uses charsetutf-8; 3. Select the UTF-8 encoding format when saving HTML files in the editor. These three links are indispensable, otherwise it may lead to garbled page code and failure of special character parsing, affecting user experience and SEO effect. It is important to ensure that HTML declaration, server configuration and file saving are consistent.

ShadowDOM is a technology used in web component technology to create isolated DOM subtrees. 1. It allows the mount of an independent DOM structure on ordinary HTML elements, with its own styles and behaviors, and does not affect the main document; 2. Created through JavaScript, such as using the attachShadow method and setting the mode to open; 3. When used in combination with HTML, it has three major features: clear structure, style isolation and content projection (slot); 4. Notes include complex debugging, style scope control, performance overhead and framework compatibility issues. In short, ShadowDOM provides native encapsulation capabilities for building reusable and non-polluting UI components.