效果预览

源代码下载

每日前端实战系列的全部源代码请从 github 下载：

https://github.com/comehope/front-end-daily-challenges

代码解读

定义 dom，容器中包含 8 个子元素：

<div class="coil">
 <span></span>
 <span></span>
 <span></span>
 <span></span>
 <span></span>
 <span></span>
 <span></span>
 <span></span>
</div>

居中显示：

body {
 margin: 0;
 height: 100vh;
 display: flex;
 align-items: center;
 justify-content: center;
 background: radial-gradient(circle at center, midnightblue, black);
}

画出纹香盘要用的框线：

.coil {
 position: relative;
 display: flex;
 justify-content: center;
}

.coil span {
 position: absolute;
 width: calc((var(--n) * 2 - 1) * 1em);
 height: calc((var(--n) - 0.5) * 1em);
 border: 1em solid darkgreen;
}

.coil span:nth-child(1) {
 --n: 1;
}

.coil span:nth-child(2) {
 --n: 2;
}

.coil span:nth-child(3) {
 --n: 3;
}

.coil span:nth-child(4) {
 --n: 4;
}

.coil span:nth-child(5) {
 --n: 5;
}

.coil span:nth-child(6) {
 --n: 6;
}

.coil span:nth-child(7) {
 --n: 7;
}

.coil span:nth-child(8) {
 --n: 8;
}

把一半框线放置到上方：

.coil span:nth-child(odd) {
 align-self: flex-end;
}

删除掉上方框线的下边框，和下方框线的上边框：

.coil span:nth-child(odd) {
 border-bottom: none;
}

.coil span:nth-child(even) {
 border-top: none;
}

对齐上下边框：

.coil span:nth-child(even) {
 transform: translateX(-1em);
}

把边框改为曲线：

.coil span:nth-child(odd) {
 border-radius: 50% 50% 0 0 / 100% 100% 0 0;
}

.coil span:nth-child(even) {
 border-radius: 0 0 50% 50% / 0 0 100% 100%;
}

用伪元素画出蚊香最中间的部分：

.coil::before {
 content: '';
 position: absolute;
 width: 1em;
 height: 1em;
 background-color: darkgreen;
 border-radius: 50%;
 left: -1.5em;
 top: -0.5em;
}

用伪元素画出蚊香的燃点：

.coil::after {
 content: '';
 position: absolute;
 width: 1em;
 height: 1em;
 border-radius: 50%;
 top: -0.5em;
 background-color: darkred;
 left: -9.5em;
 z-index: -1;
 transform: scale(0.9);
 box-shadow: 0 0 1em white;
}

最后，为燃点增加闪动的效果：

.coil::after {
 animation: blink 1s linear infinite alternate;
}

@keyframes blink {
 to {
 box-shadow: 0 0 0 white;
 }
}

大功告成！