纯 CSS 实现的 Loading 效果
整理自 T. Afif 在推特分享的十个
Loading效果，全部使用纯 CSS 实现，无 JavaScript 依赖。
为保证运行正常，先规定：
css
* {
box-sizing: border-box;
}1. 平滑加载
html
<div class="progress-1"></div>css
.progress-1 {
width:120px;
height:20px;
background:
linear-gradient(#000 0 0) 0/0% no-repeat
#ddd;
animation:p1 2s infinite linear;
}
@keyframes p1 {
100% {background-size:100%}
}linear-gradient(#000 0 0)可理解为linear-gradient(#000 0 100%)，不习惯可直接写#000。0/0%是background-position: 0;/background-size: 0;的简写。
2. 按步加载
html
<div class="progress-2"></div>css
.progress-2 {
width:120px;
height:20px;
border-radius: 20px;
background:
linear-gradient(orange 0 0) 0/0% no-repeat
lightblue;
animation:p2 2s infinite steps(10);
}
@keyframes p2 {
100% {background-size:110%}
}steps(10)是steps(10, end)的简写。100% {background-size:110%}多一个 step 的百分比：100% + (1/10)*100% = 110%。
3. 条纹加载
html
<div class="progress-3"></div>css
.progress-3 {
width:120px;
height:20px;
border-radius: 20px;
background:
repeating-linear-gradient(135deg,#f03355 0 10px,#ffa516 0 20px) 0/0% no-repeat,
repeating-linear-gradient(135deg,#ddd 0 10px,#eee 0 20px) 0/100%;
animation:p3 2s infinite;
}
@keyframes p3 {
100% {background-size:100%}
}repeating-linear-gradient(135deg,#ddd 0 10px,#eee 0 20px) 0/100% 画出灰色斑马线条纹，repeating-linear-gradient(135deg,#f03355 0 10px,#ffa516 0 20px) 0/0% no-repeat 是进度条纹。
4. 虚线加载
html
<div class="progress-4"></div>css
.progress-4 {
width:120px;
height:20px;
-webkit-mask:linear-gradient(90deg,#000 70%,#0000 0) 0/20%;
background:
linear-gradient(#000 0 0) 0/0% no-repeat
#ddd;
animation:p4 2s infinite steps(6);
}
@keyframes p4 {
100% {background-size:120%}
}-webkit-mask 默认 repeat，否则遮罩不会重复出五个。
5. 电池加载
html
<div class="progress-5"></div>css
.progress-5 {
width:80px;
height:40px;
border:2px solid #000;
padding:3px;
background:
repeating-linear-gradient(90deg,#000 0 10px,#0000 0 16px)
0/0% no-repeat content-box content-box;
position: relative;
animation:p5 2s infinite steps(6);
}
.progress-5::before {
content:"";
position: absolute;
top: 50%;
left:100%;
transform: translateY(-50%);
width:10px;
height: 10px;
border: 2px solid #000;
}
@keyframes p5 {
100% {background-size:120%}
}6. 内嵌加载
html
<div class="progress-6"></div>css
.progress-6 {
width:120px;
height:22px;
border-radius: 20px;
color: #514b82;
border:2px solid;
position: relative;
}
.progress-6::before {
content:"";
position: absolute;
margin:2px;
inset:0 100% 0 0;
border-radius: inherit;
background: #514b82;
animation:p6 2s infinite;
}
@keyframes p6 {
100% {inset:0}
}inset:0 100% 0 0; 右边内缩 100%，keyframes 中需将 inset 设为 0。
7. 珠链加载
html
<div class="progress-7"></div>css
.progress-7 {
width:120px;
height:24px;
-webkit-mask:
radial-gradient(circle closest-side,#000 94%,#0000) 0 0/25% 100%,
linear-gradient(#000 0 0) center/calc(100% - 12px) calc(100% - 12px) no-repeat;
background:
linear-gradient(#25b09b 0 0) 0/0% no-repeat
#ddd;
animation:p7 2s infinite linear;
}
@keyframes p7 {
100% {background-size:100%}
}遮罩 -webkit-mask 中 radial-gradient 将宽度四等份，每份以最小 closest-side 的边为直径画圆。
8. 斑马线加载
html
<div class="progress-8"></div>css
.progress-8 {
width:60px;
height:60px;
border-radius: 50%;
-webkit-mask:linear-gradient(0deg,#000 55%,#0000 0) bottom/100% 18.18%;
background:
linear-gradient(#f03355 0 0) bottom/100% 0% no-repeat
#ddd;
animation:p8 2s infinite steps(7);
}
@keyframes p8 {
100% {background-size:100% 115%}
}对 linear-gradient 角度做调整，再加蒙版。
9. 水柱加载
html
<div class="progress-9"></div>css
.progress-9 {
--r1: 154%;
--r2: 68.5%;
width:60px;
height:60px;
border-radius: 50%;
background:
radial-gradient(var(--r1) var(--r2) at top ,#0000 79.5%,#269af2 80%) center left,
radial-gradient(var(--r1) var(--r2) at bottom,#269af2 79.5%,#0000 80%) center center,
radial-gradient(var(--r1) var(--r2) at top ,#0000 79.5%,#269af2 80%) center right,
#ccc;
background-size: 50.5% 220%;
background-position: -100% 0%,0% 0%,100% 0%;
background-repeat:no-repeat;
animation:p9 2s infinite linear;
}
@keyframes p9 {
33% {background-position: 0% 33% ,100% 33% ,200% 33% }
66% {background-position: -100% 66%,0% 66% ,100% 66% }
100% {background-position: 0% 100%,100% 100%,200% 100%}
}radial-gradient 画出水平面波动（三个圆），var(--r1) 调用定义好的属性值。
10. 信号加载
html
<div class="progress-10"></div>css
.progress-10 {
width:120px;
height:60px;
border-radius:200px 200px 0 0;
-webkit-mask:repeating-radial-gradient(farthest-side at bottom ,#0000 0,#000 1px 12%,#0000 calc(12% + 1px) 20%);
background:
radial-gradient(farthest-side at bottom,#514b82 0 95%,#0000 0) bottom/0% 0% no-repeat
#ddd;
animation:p10 2s infinite steps(6);
}
@keyframes p10 {
100% {background-size:120% 120%}
}用 repeating-radial-gradient 画出环状蒙版遮罩，radial-gradient 从底部向上做圆形渐变填充。
原文配图见原作者推特分享，本文保留代码与原理说明。