There are five ways to include CSS in React: 1. Use inline styles, which are simple but not conducive to reuse and maintenance; 2. Use CSS files, which are implemented through import, which are conducive to organization but may lead to conflicts; 3. Use CSSModules to avoid global conflicts but require configuration; 4. Use StyledComponents to dynamically generate styles using JavaScript but require dependency on libraries; 5. Use Sass or Less to provide more functions but increase construction complexity.

There are three main ways to generate encrypted signatures in PHP. 1. Use hash_hmac for HMAC signatures, and generate signatures through key and hash algorithms (such as sha256), which is suitable for API interface requests and callback verification; 2. Use openssl_sign to implement RSA signatures, using private key signatures and public key verification, which are suitable for high-security scenarios such as payment callbacks; 3. Signing after splicing parameters, which is often used in API interfaces. The parameters need to be sorted according to rules and added with keys to generate signatures to prevent replay attacks. In addition, the signature field is recommended to be unified into sign or signature and transmitted over HTTPS to ensure security.

There are three ways to selectively include CSS on a specific page: 1. Inline CSS, suitable for pages that are not frequently accessed or require unique styles; 2. Load external CSS files using JavaScript conditions, suitable for situations where flexibility is required; 3. Containment on the server side, suitable for scenarios using server-side languages. This approach can optimize website performance and maintainability, but requires balance of modularity and performance.

ThedifferentmethodsforincludingCSSinawebpageareinline,internal,andexternalCSS.1)InlineCSS:Easytoimplementbutleadstounmaintainablecode.2)InternalCSS:MoreorganizedthaninlinebutcanclutterHTML.3)ExternalCSS:Bestforlargerprojects,promotesmaintainabilityan

HTML, CSS and JavaScript are responsible for structure, style and dynamic functions in web development respectively. 1. HTML defines the web structure, 2. CSS is responsible for style and layout, 3. JavaScript provides dynamic interaction and functions.

The overflow attribute handles overflow content by hiding, scrolling or automatically adjusting. The main values ??include 1. Hidden direct cropping; 2. Scroll always displays scroll bars; 3. Auto displays scroll bars as needed; 4. Overflow-x and overflow-y can control horizontal and vertical overflow respectively. 1. overflow:hidden is used to avoid overflow of content; 2. overflow:scroll is suitable for chat windows or fixed-size sidebars to keep the interface consistent; 3. overflow:auto is suitable for tables or user-generated content to achieve flexible scrolling; 4. Note when setting overflow-x and overflow-y independently

CSS blocks page rendering because browsers view inline and external CSS as key resources by default, especially with imported stylesheets, header large amounts of inline CSS, and unoptimized media query styles. 1. Extract critical CSS and embed it into HTML; 2. Delay loading non-critical CSS through JavaScript; 3. Use media attributes to optimize loading such as print styles; 4. Compress and merge CSS to reduce requests. It is recommended to use tools to extract key CSS, combine rel="preload" asynchronous loading, and use media delayed loading reasonably to avoid excessive splitting and complex script control.

The future development direction of CSS is exciting, and its core lies in the fact that language is gradually meeting the needs of modern web development. 1. The native cascade layer provides better style priority control to reduce specific conflicts; 2. The sub-grid supports the alignment of nested elements with the parent container to avoid redundant code; 3. Container query allows components to adapt based on container size to promote true component design; 4.:has() selector can set the conditional style according to the state of the internal element to reduce JavaScript dependencies. These features mark the positive evolution of CSS in a more expressive and logical direction. Some functions have been available in modern browsers. Familiarity with them in advance will help future project practices.