.calendar {
    display: grid;
    grid-template-columns: repeat(7, 1fr);
    gap: 5px;
}
.day {
    height: 80px;
    display: flex;
    align-items: center;
    justify-content: center;
    font-weight: bold;
    border-radius: 5px;
    cursor: pointer;
    transition: 0.3s;
}
.day:hover {
    opacity: 0.8;
}
.empty {
    background: none;
    pointer-events: none;
}