Selector.css

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/*активная кнопка*/
.sy {
    padding: 3px;
        background: transparent;
    border: 3px solid transparent;
        width: 64px;
    height: 64px;
}
/*обычная кнопка*/
.sn {
    padding: 3px;
    border: 3px solid transparent;
        width: 64px;
    height: 64px;
    background: transparent;
}