前端每日实战：16#视频演示如何用纯CSS创作一个渐变色动画边框

效果预览

按下右侧的“点击预览”按钮可以在当前页面预览&＃xff0c;点击链接可以全屏预览。

https://codepen.io/comehope/pen/odpRKX

可交互视频教程

此视频是可以交互的&＃xff0c;你可以随时暂停视频&＃xff0c;编辑视频中的代码。

请用 chrome, safari, edge 打开观看。

https://scrimba.com/c/cmQV7Hd

源代码下载

请从 github 下载。

https://github.com/comehope/front-end-daily-challenges/tree/master/016-colorful-gradient-animated-border

代码解读

定义 dom&＃xff0c;一个容器中包含一些文字&＃xff1a;

居中显示&＃xff1a;

html,
body,
.box {height: 100%;display: flex;align-items: center;justify-content: center;
}

设置页面背景色&＃xff1a;

body {background: #222;
}

设置容器和文字样式&＃xff1a;

.box {color: white;font-size: 2.5em;width: 10em;height: 5em;background: #111;font-family: sans-serif;line-height: 1.5em;text-align: center;border-radius: 0.2em;
}

用伪元素增加一个背板&＃xff1a;

.box {position: relative;
}.box::after {content: &＃39;&＃39;;position: absolute;width: 102%;height: 104%;background-color: orange;z-index: -1;border-radius: 0.2em;
}

把背板设置为渐变色的&＃xff1a;

.box::after {/*background-color: orange;*/background-image: linear-gradient(60deg, aquamarine, cornflowerblue, goldenrod, hotpink, salmon, lightgreen, sandybrown, violet);
}

为背板设置动画效果&＃xff1a;

.box::after {background-size: 300%, 300%;animation: animate_bg 5s ease infinite alternate;
}&＃64;keyframes animate_bg {0% {background-position: 0%, 50%;}50% {background-position: 100%, 50%;}100% {background-position: 0%, 50%;}
}

最后&＃xff0c;再为文字增加变色效果&＃xff1a;

.box {animation: animate_text 2s linear infinite alternate;
}&＃64;keyframes animate_text {from {color: lime;}to {color: yellow;}
}

大功告成&＃xff01;

知识点

• z-index https://developer.mozilla.org/en-US/docs/Web/CSS/z-index
• background-image https://developer.mozilla.org/en-US/docs/Web/CSS/background-image
• background-size https://developer.mozilla.org/en-US/docs/Web/CSS/background-size
• background-position https://developer.mozilla.org/en-US/docs/Web/CSS/background-position