datepicker.css

datepicker * {
    box-sizing: border-box;
}

datepicker {
    max-width: 420px;
    width: 100%;
    display: inline-block;
    position: relative;
}

.datepicker-container {
    border: 1px solid #dddddd;
    border-radius: 6px;
    box-shadow: 0 3px 10px rgb(0 0 0 / 20%);
    padding: 10px 0;
    width: 100%;
    display: none;
    background-color: #fff;
    position: absolute;
    z-index: 99;
    max-width: 350px;
}

.dp-month {
    display: flex;
    flex-direction: column;
}

.dp-weekdays {
    display: grid;
    grid-template-columns: repeat(7, 1fr);
    align-items: center;
    padding: 0 2px;

}

.dp-weekdays > span {
    text-align: center;
    margin: 0;
    font-size: 14px;
    font-weight: bold;
    padding: 6px 0;
}

.dp-days-of-month {
    width: 100%;
    margin: 0;
    display: grid;
    grid-template-columns: repeat(7, 1fr);
    padding: 2px;
}

.dp-days-of-month > span {
    text-align: center;
    display: inline-block;
    border: 2px solid #fff;
}

.dp-days-of-month > span:hover {
    cursor: pointer;
    border: 2px solid #DADADA;
}

.dp-days-of-month > span:not(:hover) {
    border-bottom: 2px solid #fff;
}


.dp-days-of-month > span[next-month],
.dp-days-of-month > span[previous-month] {
    /*background-color: #F1F5FA;*/
    opacity: 0.5;
}

.dp-days-of-month span[today] {
    color: #ff5722;
}

.dp-days-of-month > span[selected] {
    border: 2px solid #A8A9AD;
}

.dp-controller {
    display: flex;
    padding: 10px 20px;
    justify-content: space-between;
}

.dp-controller > div {
    flex-shrink: 1;
    flex-grow: 1;
    display: flex;
    justify-content: center;
    gap: 12px;
}

.dp-controller button {
    padding: 7px 14px;
    font-size: 20px;
    border: none;
    background: #e8e8e8;
    border-radius: 4px;
    cursor: pointer;
    outline: none;
}

.dp-controller-btn {
    margin: 0 auto;
}

.dp-month-list,
.dp-year-list {
    display: grid;
    grid-template-columns: repeat(4, 1fr);
    justify-content: space-between;
    align-items: center;

}


.dp-month-list > span:hover,
.dp-year-list > span:hover {
    background-color: #E8E8EA;
    border-radius: 4px;
}

.dp-month-list > span,
.dp-year-list > span {
    margin: 10px;
    padding: 10px 0;
    text-align: center;
}