JSFiddle - React, Tailwind, and code Playground

HTML

<div class="row calender">
                        <div class="col-xs-12">
                            <div class="cal-row">
                                <div class="cal-cell">
                                    <div class="number">
                                        <div class="number-inner">30</div>
                                    </div>
                                </div>
                                <div class="cal-cell">
                                    <div class="number">
                                        <div class="number-inner">1</div>
                                    </div>
                                </div>
                                <div class="cal-cell">
                                    <div class="number">
                                        <div class="number-inner">2</div>
                                    </div>
                                </div>
                                <div class="cal-cell">
                                    <div class="number">
                                        <div class="number-inner">3</div>
                                    </div>
                                </div>
                                <div class="cal-cell">
                                    <div class="number">
                                        <div class="number-inner">4</div>
                                    </div>
                                </div>
                                <div class="cal-cell">
                                    <div class="number">
                                        <div class="number-inner">5</div>
                                    </div>
                                </div>
                                <div class="cal-cell">
                                    <div class="number">
                                        <div class="number-inner">6</div>
                                    </div>
                               ...

CSS

.weekday_bg {
    background: rgba(0, 0, 0, 0.5);
    position: relative;
    z-index: 999;
    margin-top: -78px;
    font-size: 0;
}

.weekday {
    width: 14.2857142857%;
    display: inline-block;
    text-align: center;
    padding: 15px 0;
}

.today_is {
    color: #94979e;
    font-size: 14px;
}

.month {
    text-transform: uppercase;
}

.day-of-week {
    font-size: 14px;
    color: #7da9d7;
    text-transform: uppercase;
    padding-top: 10px;
}

.days_bg {
    background: #575757;
    margin-bottom: 30px;
}

.weekday:hover,
.today {
    border-bottom: 5px solid #2bb0ff;
    padding-bottom: 10px;
}

.cal-row {
    font-size: 0;
    background: #464646;
}

.cal-cell {
    display: inline-block;
    width: 14.2857142857%;
    text-align: center;
    margin: 0px;
}

.cal-cell .number {
    font-size: 24px;
    color: #97c9ff;
    background: #575757;
    padding: 2px 0;
    border-bottom: 1px solid #717171;
    margin-top: 1px;
    margin-left: 1px;
}

.number-inner {
    margin: 1px;
}

.bluebordered {
    border: 1px solid #219fff;
    margin: 0;
}

.cal-cell .choosen {
    background: #219fff;
    color: #fff;
}

.calendar {
    margin-bottom: 30px;
}