Wave Fill
Selected radio fills with a sine-wave water animation — uses a moving SVG-free CSS wave for an organic liquid feel.
Wave Fill the 12th of 18 designs in the 18 CSS Radio Button Designs collection. The design is implemented in pure CSS — no JavaScript required. Copy the HTML and CSS panels below into your project. Because the demo is pure CSS, it works in any framework or templating engine you happen to use. The design honours prefers-reduced-motion and uses real semantic markup, so it ships accessibility-ready out of the box.
Live preview
The code
<fieldset class="crb-wave"> <legend class="crb-sr">Volume</legend> <label><input type="radio" name="crb-wave" /><span></span>Low</label> <label><input type="radio" name="crb-wave" checked /><span></span>Mid</label> <label><input type="radio" name="crb-wave" /><span></span>Loud</label> </fieldset>
.crb-wave { display: flex; flex-direction: column; gap: 10px; border: 0; padding: 0; }
.crb-wave label {
display: flex; align-items: center; gap: 10px;
font: 500 13px/1 system-ui, sans-serif; color: #cbd5e1; cursor: pointer;
}
.crb-wave input { appearance: none; -webkit-appearance: none; position: absolute; opacity: 0; }
.crb-wave span {
width: 20px; height: 20px; border-radius: 50%;
border: 2px solid #444461;
position: relative; overflow: hidden;
background: transparent;
transition: border-color 0.25s;
}
.crb-wave span::before {
content: ''; position: absolute;
top: 100%; left: -50%; width: 200%; height: 200%;
background: radial-gradient(ellipse at top, transparent 40%, #06b6d4 41%);
transition: top 0.5s ease-out;
}
.crb-wave input:checked + span { border-color: #06b6d4; }
.crb-wave input:checked + span::before {
top: -10%;
animation: crb-wave-bob 1.4s ease-in-out infinite;
}
@keyframes crb-wave-bob {
0%,100% { transform: translateY(0); }
50% { transform: translateY(-2px); }
}
@media (prefers-reduced-motion: reduce) {
.crb-wave,
.crb-wave * {
animation: none !important;
}
}
.crb-sr {
position: absolute !important;
width: 1px;
height: 1px;
padding: 0;
margin: -1px;
overflow: hidden;
clip: rect(0, 0, 0, 0);
white-space: nowrap;
border: 0;
}