Карта, сгенерированная листовкой, имеет z-index 999 и кнопку масштабирования 1000 Итак, вы сгенерировали datetimepicker div (bottom div) по умолчанию z-index = 1;
Так что просто добавьте к вам css нижеприведенный код, и он будет показан в верхней части карты:
.datepicker {
z-index:1001 !important;
}
(! Здесь важно переопределить свойство set css по умолчанию)
См. Ниже рабочий фрагмент:
$(function() {
$("#datepicker").datepicker({
});
var map = L.map('map').setView([41.85, -87.6298], 11);
// load a tile layer
L.tileLayer('https://api.mapbox.com/styles/v1/kuhugupta/cjo4txr7o02i12rn8pr2x1cji/tiles/{z}/{x}/{y}?access_token=pk.eyJ1Ijoia3VodWd1cHRhIiwiYSI6ImNpcDgxYmg1YzAxN2hzem5yaXRtaDN6dWYifQ.hAIOSatYipnZ-NnqodCQFg', {
attribution: 'Map data © <a href="http://openstreetmap.org">OpenStreetMap</a> contributors, <a href="http://creativecommons.org/licenses/by-sa/2.0/">CC-BY-SA</a>, Imagery © <a href="http://mapbox.com">Mapbox</a>',
maxZoom: 18,
username: 'XXXXX',
id: 'xxxxx',
tileSize: 512,
zoomOffset: -1,
accessToken: 'xxxxx'
}).addTo(map);
});
body {
font-family: 'tahoma';
font-size: 14px;
overflow-y: hidden;
}
.navbar {
padding: 0px 1rem;
}
.navbar .navbar-brand {
font-size: 14px;
color: #000;
}
.navbar .row {
width: 100%;
}
.navbar .row .columns {
padding-top: 7px;
}
.navbar .form-group {
padding-bottom: 7px;
margin-bottom: 0px;
}
.navbar .form-group label {
color: #000;
}
.navbar .form-group select {
padding: 3px;
}
.map-block {
padding-left: 0px;
padding-right: 0px;
}
.padd-top-20 {
padding-top: 15px;
}
.junk_charts {
background-color: silver;
position: relative;
overflow: scroll;
height: 700px;
}
.datepicker {
z-index:1001 !important;
}
<script src="https://ajax.googleapis.com/ajax/libs/jquery/2.1.1/jquery.min.js"></script>
<script src="https://unpkg.com/leaflet@1.3.4/dist/leaflet.js"
integrity="sha512-nMMmRyTVoLYqjP9hrbed9S+FzjZHW5gY1TWCHA5ckwXZBadntCNs8kEqAWdrb9O7rxbCaA4lKTIWjDXZxflOcA=="
crossorigin=""></script>
<link rel="stylesheet" href="https://unpkg.com/leaflet@1.3.4/dist/leaflet.css"
integrity="sha512-puBpdR0798OZvTTbP4A8Ix/l+A4dHDD0DGqYW6RQ+9jxkRFclaxxQb/SJAWZfWAkuyeQUytO7+7N4QKrDh+drA=="
crossorigin=""/>
<link rel="stylesheet" href="https://maxcdn.bootstrapcdn.com/bootstrap/4.0.0-beta.2/css/bootstrap.min.css" integrity="sha384-PsH8R72JQ3SOdhVi3uxftmaW6Vc51MKb0q5P2rRUpPvrszuE4W1povHYgTpBfshb" crossorigin="anonymous">
<link href="https://cdnjs.cloudflare.com/ajax/libs/bootstrap-datepicker/1.7.1/css/bootstrap-datepicker.min.css" rel="stylesheet" />
<link rel="stylesheet" href="./style.css">
<div id="main">
<nav class="navbar navbar-expand-sm bg-light navbar-dark">
<div class="row">
<div class="col-md-4 columns"><a class="navbar-brand" href="">Crime Prediction</a></div>
<div class="col-md-1 columns">
</div>
<div class="col-md-2 columns">
<input data-date-format="dd/mm/yyyy" id="datepicker" class='bdate'>
</div>
<div class="col-md-2 columns">
</div>
<div class="col-md-3 columns">
</div>
</div>
</nav>
<div class="container-fluid">
<div class="row">
<div class="col-md-8 col-sm-12 map-block">
<div class="row">
<div class="col-sm-12">
<div id="map" style="width:100%;height:100vh;">Hey</div>
</div>
</div>
</div>
<div class="col-md-4 col-sm-12 junk_charts">
<div class="row">
<div class="col-sm-12">
</div>
</div>
</div>
</div>
</div>
</div>
<script src="https://cdnjs.cloudflare.com/ajax/libs/popper.js/1.12.3/umd/popper.min.js" integrity="sha384-vFJXuSJphROIrBnz7yo7oB41mKfc8JzQZiCq4NCceLEaO4IHwicKwpJf9c9IpFgh" crossorigin="anonymous"></script>
<script src="https://maxcdn.bootstrapcdn.com/bootstrap/4.0.0-beta.2/js/bootstrap.min.js" integrity="sha384-alpBpkh1PFOepccYVYDB4do5UnbKysX5WZXm3XxPqe5iKTfUKjNkCk9SaVuEZflJ" crossorigin="anonymous"></script>
<script src="https://cdnjs.cloudflare.com/ajax/libs/bootstrap-datepicker/1.7.1/js/bootstrap-datepicker.min.js"></script>