span.checkbox.tristate {
    background-color: rgb(255 255 255 / 15%);
    border: solid 1px rgb(255 255 255 / 15%);
    border-radius: 4px;
    display: inline-block;
    height: 14px;
    margin-right: .25rem;
    text-align: center;
    width: 14px;
    vertical-align: middle;
    transition: background-color .15s ease-in-out, background-position .15s ease-in-out, border-color .15s ease-in-out, box-shadow .15s ease-in-out;
}

span.checkbox.tristate svg {
    margin-bottom: 8px;
    stroke: #fff;
}

.label {
}

span.checkbox.tristate ~ label {
    user-select: none;
    vertical-align: middle;
}

span.tristate {
    user-select: none;
}