HTMLify

* {
    border: 0;
    box-sizing: border-box;
    margin: 0;
    padding: 0;
}

:root {
    font-size: calc(32px + (40 - 32)*(100vw - 320px)/ (1024 - 320));
}

body {
    background: #151515;
    color: #e3e4e8;
    display: flex;
    font: 1em Hind, sans-serif;
    height: 100vh;
    line-height: 1.5;
}

form {
    display: block;
    margin: auto;
    max-width: 10em;
    position: relative;
}

input {
    position: fixed;
    top: -1.5em;
    left: -1.5em;
}

label {
    cursor: pointer;
    display: block;
    font-weight: bold;
    text-shadow: 0 0.1em 0.1em rgba(0, 0, 0, 0.2);
    transition: color 0.2s cubic-bezier(0.45, 0.05, 0.55, 0.95);
}

label:not(:last-of-type) {
    margin-bottom: 1.5em;
}

label span {
    box-shadow: 0 0 0 0.2em currentColor inset, 0 0.2em 0.2em rgba(0, 0, 0, 0.2), 0 0.3em 0.2em rgba(0, 0, 0, 0.2) inset;
    display: inline-block;
    margin-right: 0.5em;
    vertical-align: bottom;
    width: 1.5em;
    height: 1.5em;
    transition: transform 0.2s cubic-bezier(0.5, 0, 0.5, 2), box-shadow 0.2s cubic-bezier(0.45, 0.05, 0.55, 0.95), color 0.2s cubic-bezier(0.45, 0.05, 0.55, 0.95);
}

label span,
.worm__segment:before {
    border-radius: 50%;
}

input:checked+label,
input:checked+label span,
.worm__segment:before {
    color: #e1f655;
}

input:checked+label,
input:checked+label span {
    transition-delay: 0.4s;
}

input:checked+label span {
    transform: scale(1.2);
}

.worm {
    top: 0.375em;
    left: 0.375em;
}

.worm,
.worm__segment {
    position: absolute;
}

.worm__segment {
    top: 0;
    left: 0;
    width: 0.75em;
    height: 0.75em;
    transition: transform 0.4s cubic-bezier(0.45, 0.05, 0.55, 0.95);
}

.worm__segment:before {
    animation-duration: 0.4s;
    animation-timing-function: cubic-bezier(0.45, 0.05, 0.55, 0.95);
    background: currentColor;
    content: "";
    display: block;
    width: 100%;
    height: 100%;
}

.worm__segment:first-child:before,
.worm__segment:last-child:before {
    box-shadow: 0 0 1em 0 currentColor;
}

.worm__segment:nth-child(2) {
    transition-delay: 0.004s;
}

.worm__segment:nth-child(2):before {
    animation-delay: 0.004s;
}

.worm__segment:nth-child(3) {
    transition-delay: 0.008s;
}

.worm__segment:nth-child(3):before {
    animation-delay: 0.008s;
}

.worm__segment:nth-child(4) {
    transition-delay: 0.012s;
}

.worm__segment:nth-child(4):before {
    animation-delay: 0.012s;
}

.worm__segment:nth-child(5) {
    transition-delay: 0.016s;
}

.worm__segment:nth-child(5):before {
    animation-delay: 0.016s;
}

.worm__segment:nth-child(6) {
    transition-delay: 0.02s;
}

.worm__segment:nth-child(6):before {
    animation-delay: 0.02s;
}

.worm__segment:nth-child(7) {
    transition-delay: 0.024s;
}

.worm__segment:nth-child(7):before {
    animation-delay: 0.024s;
}

.worm__segment:nth-child(8) {
    transition-delay: 0.028s;
}

.worm__segment:nth-child(8):before {
    animation-delay: 0.028s;
}

.worm__segment:nth-child(9) {
    transition-delay: 0.032s;
}

.worm__segment:nth-child(9):before {
    animation-delay: 0.032s;
}

.worm__segment:nth-child(10) {
    transition-delay: 0.036s;
}

.worm__segment:nth-child(10):before {
    animation-delay: 0.036s;
}

.worm__segment:nth-child(11) {
    transition-delay: 0.04s;
}

.worm__segment:nth-child(11):before {
    animation-delay: 0.04s;
}

.worm__segment:nth-child(12) {
    transition-delay: 0.044s;
}

.worm__segment:nth-child(12):before {
    animation-delay: 0.044s;
}

.worm__segment:nth-child(13) {
    transition-delay: 0.048s;
}

.worm__segment:nth-child(13):before {
    animation-delay: 0.048s;
}

.worm__segment:nth-child(14) {
    transition-delay: 0.052s;
}

.worm__segment:nth-child(14):before {
    animation-delay: 0.052s;
}

.worm__segment:nth-child(15) {
    transition-delay: 0.056s;
}

.worm__segment:nth-child(15):before {
    animation-delay: 0.056s;
}

.worm__segment:nth-child(16) {
    transition-delay: 0.06s;
}

.worm__segment:nth-child(16):before {
    animation-delay: 0.06s;
}

.worm__segment:nth-child(17) {
    transition-delay: 0.064s;
}

.worm__segment:nth-child(17):before {
    animation-delay: 0.064s;
}

.worm__segment:nth-child(18) {
    transition-delay: 0.068s;
}

.worm__segment:nth-child(18):before {
    animation-delay: 0.068s;
}

.worm__segment:nth-child(19) {
    transition-delay: 0.072s;
}

.worm__segment:nth-child(19):before {
    animation-delay: 0.072s;
}

.worm__segment:nth-child(20) {
    transition-delay: 0.076s;
}

.worm__segment:nth-child(20):before {
    animation-delay: 0.076s;
}

.worm__segment:nth-child(21) {
    transition-delay: 0.08s;
}

.worm__segment:nth-child(21):before {
    animation-delay: 0.08s;
}

.worm__segment:nth-child(22) {
    transition-delay: 0.084s;
}

.worm__segment:nth-child(22):before {
    animation-delay: 0.084s;
}

.worm__segment:nth-child(23) {
    transition-delay: 0.088s;
}

.worm__segment:nth-child(23):before {
    animation-delay: 0.088s;
}

.worm__segment:nth-child(24) {
    transition-delay: 0.092s;
}

.worm__segment:nth-child(24):before {
    animation-delay: 0.092s;
}

.worm__segment:nth-child(25) {
    transition-delay: 0.096s;
}

.worm__segment:nth-child(25):before {
    animation-delay: 0.096s;
}

.worm__segment:nth-child(26) {
    transition-delay: 0.1s;
}

.worm__segment:nth-child(26):before {
    animation-delay: 0.1s;
}

.worm__segment:nth-child(27) {
    transition-delay: 0.104s;
}

.worm__segment:nth-child(27):before {
    animation-delay: 0.104s;
}

.worm__segment:nth-child(28) {
    transition-delay: 0.108s;
}

.worm__segment:nth-child(28):before {
    animation-delay: 0.108s;
}

.worm__segment:nth-child(29) {
    transition-delay: 0.112s;
}

.worm__segment:nth-child(29):before {
    animation-delay: 0.112s;
}

.worm__segment:nth-child(30) {
    transition-delay: 0.116s;
}

.worm__segment:nth-child(30):before {
    animation-delay: 0.116s;
}

/* States */
input:nth-of-type(1):checked~.worm .worm__segment:before {
    animation-name: hop1;
}

@keyframes hop1 {

    from,
    to {
        transform: translateX(0);
    }

    50% {
        transform: translateX(-1.5em);
    }
}

input:nth-of-type(2):checked~.worm .worm__segment {
    transform: translateY(3em);
}

input:nth-of-type(2):checked~.worm .worm__segment:before {
    animation-name: hop2;
}

@keyframes hop2 {

    from,
    to {
        transform: translateX(0);
    }

    50% {
        transform: translateX(-1.5em);
    }
}

input:nth-of-type(3):checked~.worm .worm__segment {
    transform: translateY(6em);
}

input:nth-of-type(3):checked~.worm .worm__segment:before {
    animation-name: hop3;
}

@keyframes hop3 {

    from,
    to {
        transform: translateX(0);
    }

    50% {
        transform: translateX(-1.5em);
    }
}