.size-radio {
    display: none;
}

.size-block {
    min-width: 60px;
    height: 45px;
    border: 1px solid #ddd;
    border-radius: 8px;
    display: flex;
    align-items: center;
    justify-content: center;
    padding: 0 14px;
    cursor: pointer;
    font-weight: 600;
    transition: all .2s ease;
    background: #fff;
}

.size-block:hover {
    border-color: #000;
}

.size-radio:checked + .size-block {
    background: #000;
    color: #fff;
    border-color: #000;
}

.size-block.out-of-stock {
    opacity: 0.4;
    cursor: not-allowed;
    text-decoration: line-through;
}