Fill Toggle Switch
The knob rests in a small cup of color and drags the fill behind it as it slides, so the track floods with your accent from the left. The fill is a pill moved with transform, not an animated width.
Also known as: progress fill toggle switch, slide to fill switch, trail toggle css.
HTML
<label class="tgl-fill"> <input type="checkbox" role="switch" aria-label="Auto-save"> <span class="tgl-fill-track" aria-hidden="true"><span class="tgl-fill-bar"></span></span> </label>
CSS
.tgl-fill {
--c: var(--tgl-color, #3b82f6);
font-size: var(--tgl-size, 24px);
position: relative;
display: inline-block;
vertical-align: middle;
cursor: pointer;
-webkit-tap-highlight-color: transparent;
}
.tgl-fill input {
position: absolute;
inset: 0;
width: 100%;
height: 100%;
margin: 0;
opacity: 0;
cursor: pointer;
z-index: 1;
}
.tgl-fill-track {
position: relative;
isolation: isolate;
display: block;
width: 3.8em;
height: 2em;
border-radius: 1em;
overflow: hidden;
background: color-mix(in srgb, currentColor 13%, transparent);
}
/* a full-width pill whose right end always hugs the knob */
.tgl-fill-bar {
position: absolute;
inset: 0;
border-radius: inherit;
background: var(--c);
transform: translateX(-1.8em);
transition: transform 0.45s cubic-bezier(0.65, 0, 0.35, 1);
}
.tgl-fill-track::after {
content: "";
position: absolute;
top: 0.2em;
left: 0.2em;
width: 1.6em;
height: 1.6em;
border-radius: 50%;
background: #fff;
box-shadow: 0 0.1em 0.3em rgb(0 0 0 / 0.25);
transition: transform 0.45s cubic-bezier(0.65, 0, 0.35, 1);
}
.tgl-fill input:checked + .tgl-fill-track .tgl-fill-bar { transform: none; }
.tgl-fill input:checked + .tgl-fill-track::after { transform: translateX(1.8em); }
.tgl-fill input:focus-visible + .tgl-fill-track {
outline: 2px solid var(--c);
outline-offset: 2px;
}
@media (prefers-reduced-motion: reduce) {
.tgl-fill, .tgl-fill *, .tgl-fill::before, .tgl-fill::after, .tgl-fill *::before, .tgl-fill *::after {
animation-duration: 0.01ms !important;
animation-iteration-count: 1 !important;
transition-duration: 0.01ms !important;
}
}Customizing this snippet
- Color: set
--tgl-coloron the element or a parent. Currently previewing#3b82f6. - Size: set
--tgl-size. Every other dimension is inem, so the whole thing scales together. Currently previewing24px. - Speed: change the duration on the
transitionoranimationshorthand. Staggered delays are relative, so they keep their rhythm. - Reduced motion: the rule at the end of the CSS turns the motion off for people who asked their OS for less of it. Keep it.