How to select the third li element in css3

Backdrop-filter is used to apply visual effects to the content behind the elements. 1. Use backdrop-filter:blur(10px) and other syntax to achieve the frosted glass effect; 2. Supports multiple filter functions such as blur, brightness, contrast, etc. and can be superimposed; 3. It is often used in glass card design, and it is necessary to ensure that the elements overlap with the background; 4. Modern browsers have good support, and @supports can be used to provide downgrade solutions; 5. Avoid excessive blur values and frequent redrawing to optimize performance. This attribute only takes effect when there is content behind the elements.

Theaspect-ratioCSSpropertydefinesthewidth-to-heightratioofanelement,ensuringconsistentproportionsinresponsivedesigns.1.Itisapplieddirectlytoelementslikeimages,videos,orcontainersusingsyntaxsuchasaspect-ratio:16/9.2.Commonusecasesincludemaintainingres

Define@keyframesbouncewith0%,100%attranslateY(0)and50%attranslateY(-20px)tocreateabasicbounce.2.Applytheanimationtoanelementusinganimation:bounce0.6sease-in-outinfiniteforsmooth,continuousmotion.3.Forrealism,use@keyframesrealistic-bouncewithscale(1.1

The:emptypseudo-classselectselementswithnochildrenorcontent,includingspacesorcomments,soonlytrulyemptyelementslikematchit;1.Itcanhideemptycontainersbyusing:empty{display:none;}tocleanuplayouts;2.Itallowsaddingplaceholderstylingvia::beforeor::after,wh

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Use hidden checkboxes and CSS's :checked pseudo-class combined with adjacent sibling selectors ( ) to control content display; 2. The HTML structure contains input, label and content div for each collapsed item; 3. Smooth expansion/collapse animations by setting max-height transition; 4. Add open/close status icons with pseudo-elements; 5. Use radio types to implement single-open mode, while checkbox allows multiple openings. This is an interactive foldable menu implementation that requires no JavaScript and is compatible with modern browsers.

Use CSSclip-path to create non-rectangular shapes in the browser without additional images or complex SVG; 2. Common shape functions include inset(), circle(), ellipse() and polygon(), where polygon() implements custom shapes by defining coordinate points, which is suitable for creating creative designs such as dialog bubbles; 3. clip-path can achieve dynamic effects through CSS transition or keyframe animation, such as circle expansion during hovering, but only supports inter-shape animations of the same type and number of vertices; 4. Pay attention to responsiveness and accessibility to ensure that the content is still available when not supported, the text is readable, avoid excessive cropping, and control the number of polygon vertices to optimize performance. At the same time, it is necessary to know that

vw and vh units achieve responsive design by associating element sizes with viewport width and height; 1vw is equal to 1% of viewport width, and 1vh is equal to 1% of viewport height; commonly used in full screen area, responsive fonts and elastic spacing; 1. Use 100vh or better 100dvh in the full screen area to avoid the influence of the mobile browser address bar; 2. Responsive fonts can be limited with 5vw and combined with clamp (1.5rem, 3vw, 3rem) to limit the minimum and maximum size; 3. Elastic spacing such as width:80vw, margin:5vhauto, padding:2vh3vw, can make the layout adaptable; pay attention to mobile device compatibility, accessibility and fixed width content conflicts, and it is recommended to give priority to using dvh first;