client/css/theme-toggler.css

.theme-toggler-container {
    margin: 12px 0px 8px 0px;
    justify-content: center;
}

.theme-toggler-container.checkbox input + label,
.theme-toggler-container.checkbox input:checked + label:after {
	background: var(--colour-1);
}

.theme-toggler-container.checkbox input + label:after,
.theme-toggler-container.checkbox input:checked + label {
	background: var(--colour-3);
}

.theme-toggler-container.checkbox span {
    font-size: 0.75rem;
}

.theme-toggler-container.checkbox label {
    width: 24px;
    height: 16px;
}

.theme-toggler-container.checkbox label:after {
    left: 2px;
    width: 10px;
    height: 10px;
}

.theme-toggler-container.checkbox input:checked + label:after {
    left: calc(100% - 2px - 10px);
}