CSS3 特效 - Happy New Year - 《Fuarmy 小记》

技术要点
具体实现

源码地址：GitHub

技术要点

box-shadow; 在元素的框架上添加阴影效果；参考：MDN：box-shadow
text-shadow; 为文字添加阴影；参考：MDN：text-shadow
animation; 元素的子元素可以被3D遮挡；参考：MDN：animation
transform: skewY(-7deg); 倾斜角度；参考：MDN：transform

具体实现

index.html HTML结构

<!DOCTYPE html>
<html lang="en">
<head>
  <meta charset="UTF-8">
  <meta name="viewport" content="width=device-width, initial-scale=1.0">
  <title>Happy New Year</title>
  <link rel="stylesheet" href="style.css">
</head>
<body>
  <section>
    <h2>Happy New Year<br/><span>2021</span></h2>
  </section>
  <script src="index.js"></script>
  <script>
    textShadow("h2", 80);
    textShadow("span", 20);
    stars();
  </script>
</body>
</html>

style.css 样式文件

@import url("https://fonts.googleapis.com/css?family=Poppins:200,300,400,500,600,700,800,900&display=swap");
* {
  margin: 0;
  padding: 0;
  box-sizing: border-box;
  font-family: "Poppins", sans-serif;
}
body {
  overflow: hidden;
}
section {
  display: flex;
  justify-content: center;
  align-items: center;
  min-height: 100vh;
  background: linear-gradient(135deg, #111, #222, #111);
}
section::before {
  content: "";
  position: absolute;
  width: 30vw;
  height: 30vw;
  border: 5vw solid #ff1062;
  border-radius: 50%;
  box-shadow: 0 0 0 1vw #222,
              0 0 0 1.3vw #fff;
}
section i {
  position: absolute;
  background: #fff;
  border-radius: 50%;
  box-shadow: 0 0 10px #fff,
  0 0 20px #fff,
  0 0 40px #fff,
  0 0 80px #fff;
  animation: animate 2s linear infinite;
}
@keyframes animate {
  0% {
    opacity: 0;
  }
  10% {
    opacity: 1;
  }
  90% {
    opacity: 1;
  }
  100% {
    opacity: 0;
  }
}
h2 {
  position: absolute;
  font-size: 9vw;
  color: #fff;
  text-align: center;
  line-height: 2em;
  z-index: 10;
  transform: skewY(-7deg);
  /* text-shadow: 1px 1px 0 #ccc,
  2px 2px 0 #ccc,
  3px 3px 0 #ccc,
  4px 4px 0 #ccc,
  5px 5px 0 #ccc,
  10px 10px 0 rgba(0, 0, 0, 0.2); */
  animation: floating 5s ease-in-out infinite;
}
h2 span {
  font-weight: 700;
  font-size: 3em;
  /* text-shadow: 1px 1px 0 #ccc,
  2px 2px 0 #ccc,
  3px 3px 0 #ccc,
  4px 4px 0 #ccc,
  5px 5px 0 #ccc,
  6px 6px 0 #ccc,
  7px 7px 0 #ccc,
  8px 8px 0 #ccc,
  9px 9px 0 #ccc,
  10px 10px 0 #ccc,
  20px 20px 0 rgba(0, 0, 0, 0.2); */
}
@keyframes floating {
  0%, 100% {
    transform: skewY(-7deg) translate(0, -1.5vw);
  }
  50% {
    transform: skewY(-7deg) translate(0, 1.5vw);
  }
}

index.js

/**
 * 文字效果
 * @param {string} elementQuery 文字元素
 * @param {number} cutNumber 切边（text-shadow 高度
 */
function textShadow(elementQuery, cutNumber) {
  const element = document.querySelector(elementQuery);
  let textShadow = "";
  let i=0;
  for(i; i<Math.floor(element.offsetWidth/cutNumber); i++) {
    textShadow += `${i}px ${i}px 0 #ccc,`;
  }
  element.style.textShadow = textShadow += `${i * 2}px ${i * 2}px 0 rgba(0, 0, 0, 0.2)`;
}
/**
 * 星星点状背景实现
 */
function stars() {
  const count = 200;
  const section = document.querySelector("section");
  let i = 0;
  while(i < count) {
    const star = document.createElement("i");
    const x = Math.floor(Math.random() * window.innerWidth);
    const y = Math.floor(Math.random() * window.innerHeight);
    const size = Math.random() * 4;
    star.style.left = x + "px";
    star.style.top = y + "px";
    star.style.width = 1 + size + "px";
    star.style.height = 1 + size + "px";
    const duration = Math.random() * 2;
    star.style.animationDelay = 2 + duration + "s";
    section.appendChild(star);
    i++;
  }
}

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