Briefly describe what is css?

First, set basic styles such as width, height, margins, borders, fonts and colors; 2. Enhance interactive feedback through:hover and:focus states; 3. Use the resize attribute to control the resize behavior; 4. Use the ::placeholder pseudo-element to style the placeholder text; 5. Use responsive design to ensure cross-device availability; 6. Pay attention to correlating labels, color contrast and focus outlines to ensure accessibility, and ultimately achieve a beautiful and functional textarea style.

Use HTML and CSS to create drop-down menus without JavaScript. 2. Trigger the submenu display through the :hover pseudo-class. 3. Use nested lists to build a structure, and set the hidden and suspended display effects in CSS. 4. Transition animation can be added to improve the visual experience.

Useobject-fitormax-widthwithheight:autotopreventimagedistortion;object-fitcontrolshowimagesfillcontainerswhilepreservingaspectratios,andmax-width:100%;height:autoensuresresponsivescalingwithoutstretching.

Thepointer-eventspropertyinCSScontrolswhetheranelementcanbethetargetofpointerevents.1.Usepointer-events:nonetodisableinteractionslikeclicksorhoverswhilekeepingtheelementvisuallyvisible.2.Applyittooverlaystoallowclick-throughbehaviortounderlyingelemen

Usethebox-shadowpropertytoadddropshadows.Definehorizontalandverticaloffsets,blur,spread,color,andoptionalinsetforinnershadows.Multipleshadowsarecomma-separated.Example:box-shadow:5px10px8pxrgba(0,0,0,0.3);createsasoftblackshadow.

To add a CSS gradient background, use the background or background-image attributes to cooperate with functions such as linear-gradient(), radial-gradient(); first select the gradient type, set the direction and color, and you can finely control it through color docking points, shape, size and other parameters, such as linear-gradient(toright,#ff7e5f,#feb47b) to create a linear gradient from left to right, radial-gradient(circle,#ff9a9e,#fecfef) to create a circular radial gradient, and you can also use repeating-linear-gr

TomaketextresponsiveinCSS,userelativeunitslikerem,vw,andclamp()withmediaqueries.1.Replacefixedpixelswithremforconsistentscalingbasedonrootfontsize.2.Usevwforfluidscalingbutcombinewithcalc()orclamp()topreventextremes.3.Applymediaqueriesatcommonbreakpo

Use border-radius:50% to turn images of equal width and height into circles, combine object-fit and aspect-ratio to ensure shape and cropping, and add borders, shadows and other styles to enhance visual effects.