.datetime-picker {
    position: relative;
    width: 250px;
}

.calendar-popup {
    position: absolute;
    top: 45px;
    background: white;
    border: 1px solid #ccc;
    padding: 10px;
    z-index: 1000;
    width: 260px;
    box-shadow: 0 4px 10px rgba(0,0,0,0.1);
}

.calendar-header {
    display: flex;
    justify-content: space-between;
    align-items: center;
    margin-bottom: 10px;
}

.calendar-grid {
    display: grid;
    grid-template-columns: repeat(7, 1fr);
    gap: 5px;
}

.day-header {
    font-weight: bold;
    text-align: center;
}

.day {
    text-align: center;
    padding: 5px;
    cursor: pointer;
    border-radius: 4px;
}

    .day:hover {
        background: #eee;
    }

    .day.selected {
        background: #007bff;
        color: white;
    }