Sun and Moon Dark Mode Checkbox
A sun whose rays spin inward and vanish as its disc grows into a crescent moon, with two stars blinking on. The crescent is one inset box-shadow sliding across the disc, so there is no mask or SVG.
Also known as: dark mode checkbox css, sun moon icon animation, theme toggle icon css.
HTML
<label class="chk-sun-moon-dark-mode">
<input type="checkbox">
<span class="chk-sun-moon-dark-mode-icon" aria-hidden="true">
<span class="chk-sun-moon-dark-mode-rays"><i style="--i:0"></i><i style="--i:1"></i><i style="--i:2"></i><i style="--i:3"></i><i style="--i:4"></i><i style="--i:5"></i><i style="--i:6"></i><i style="--i:7"></i></span>
<i class="chk-sun-moon-dark-mode-core"></i>
<i class="chk-sun-moon-dark-mode-star"></i>
<i class="chk-sun-moon-dark-mode-star"></i>
</span>
<span class="chk-sun-moon-dark-mode-text">Dark mode</span>
</label>CSS
.chk-sun-moon-dark-mode {
--c: var(--chk-color, #3b82f6);
font-size: var(--chk-size, 24px);
position: relative;
display: inline-flex;
align-items: center;
gap: 0.6em;
line-height: 1.3;
cursor: pointer;
-webkit-user-select: none;
user-select: none;
-webkit-tap-highlight-color: transparent;
}
.chk-sun-moon-dark-mode input {
position: absolute;
inset: 0;
width: 100%;
height: 100%;
margin: 0;
opacity: 0;
cursor: pointer;
z-index: 1;
}
.chk-sun-moon-dark-mode-icon {
position: relative;
flex: none;
width: 1.8em;
height: 1.8em;
border-radius: 50%;
}
.chk-sun-moon-dark-mode-core {
position: absolute;
left: 50%;
top: 50%;
width: 1.1em;
height: 1.1em;
margin: -0.55em;
border-radius: 50%;
box-shadow: inset 0 0 0 0.55em var(--c);
transform: rotate(0deg) scale(0.64);
transition: box-shadow 0.4s cubic-bezier(0.5, 0, 0.3, 1), transform 0.5s cubic-bezier(0.34, 1.56, 0.64, 1);
}
.chk-sun-moon-dark-mode-rays i {
position: absolute;
left: 50%;
top: 50%;
width: 0.12em;
height: 0.26em;
margin: -0.13em -0.06em;
border-radius: 1em;
background: var(--c);
transform: rotate(calc(var(--i) * 45deg)) translateY(-0.7em) scale(1);
transition: transform 0.4s cubic-bezier(0.34, 1.56, 0.64, 1) calc(0.15s + var(--i) * 0.02s), opacity 0.2s ease 0.15s;
}
.chk-sun-moon-dark-mode-star {
position: absolute;
top: 0.1em;
right: 0.05em;
width: 0.2em;
height: 0.2em;
border-radius: 50%;
background: var(--c);
transform: scale(0);
transition: transform 0.2s ease;
}
.chk-sun-moon-dark-mode-star + .chk-sun-moon-dark-mode-star {
top: 0.62em;
right: -0.14em;
width: 0.14em;
height: 0.14em;
}
.chk-sun-moon-dark-mode-text {
transition: color 0.25s ease;
}
.chk-sun-moon-dark-mode input:checked + .chk-sun-moon-dark-mode-icon .chk-sun-moon-dark-mode-core {
box-shadow: inset 0.38em -0.3em 0 0 var(--c);
transform: rotate(-20deg) scale(1);
}
.chk-sun-moon-dark-mode input:checked + .chk-sun-moon-dark-mode-icon .chk-sun-moon-dark-mode-rays i {
opacity: 0;
transform: rotate(calc(var(--i) * 45deg + 90deg)) translateY(-0.3em) scale(0);
transition: transform 0.3s ease-in, opacity 0.2s ease 0.1s;
}
.chk-sun-moon-dark-mode input:checked + .chk-sun-moon-dark-mode-icon .chk-sun-moon-dark-mode-star {
transform: scale(1);
transition: transform 0.35s cubic-bezier(0.34, 1.56, 0.64, 1) 0.35s;
}
.chk-sun-moon-dark-mode input:checked + .chk-sun-moon-dark-mode-icon .chk-sun-moon-dark-mode-star + .chk-sun-moon-dark-mode-star {
transition-delay: 0.45s;
}
.chk-sun-moon-dark-mode input:checked ~ .chk-sun-moon-dark-mode-text {
color: var(--c);
}
.chk-sun-moon-dark-mode input:focus-visible + .chk-sun-moon-dark-mode-icon {
outline: 0.12em solid var(--c);
outline-offset: 0.18em;
}
@media (prefers-reduced-motion: reduce) {
.chk-sun-moon-dark-mode, .chk-sun-moon-dark-mode *, .chk-sun-moon-dark-mode::before, .chk-sun-moon-dark-mode::after, .chk-sun-moon-dark-mode *::before, .chk-sun-moon-dark-mode *::after {
animation-duration: 0.01ms !important;
animation-iteration-count: 1 !important;
transition-duration: 0.01ms !important;
}
}Customizing this snippet
- Color: set
--chk-coloron the element or a parent. Currently previewing#3b82f6. - Size: set
--chk-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.