Fixed height for bootstrap pre-scrollable DIV

Question

In my application I have to display bootsatarp grid for database records. Since the number of records count are large enough to view without full page scrolling I wrap my table with bootstrap pre-scrollable div and it gave me the functionality to scroll the table. However all the time DIV size is half of the browser windows. I tried almost every stack overflow posts and suggestions and simply they not work for me. I also tried to fix this with support of java script and it also failed.

This is my HTML code

<div class="col-md-9">
<div  class="pre-scrollable">
<table class="table table-bordered table-hover header-fixed"  id="sometable">
                    <thead>
                  <tr>
                    <th>EMP_No</th>
                    <th>Name</th>
                    <th>Designation</th>
                    <th>Department</th>
                    <th>Type</th>
                    <th>#Days</th>
                    <th>Start Date</th>
                    <th>End Date</th>
                    <th>Half day</th>
                    <th>Status</th>
                  </tr>
                </thead>
                <tbody>
                </tbody>
                <?php  //php code for print the table
                 ?>
</div>      
</div>

I populate above table with the results of PHP code. I have not idea how to set this DIV's height to fixed value or full value of the browser windows.below are the CSS that are use

<style>
table {
    font-family: arial, sans-serif;
    border-collapse: collapse;
    width: 100%;
}
td, th {
    border: 1px solid #dddddd;
    text-align: center;
    padding: 1px;
}
thead th {
    text-align: center;
    background-color: #3498db;
}
tr:nth-child(even) {
    background-color: #dddddd;
}
</style>

This is the result web page

Answer 1

For simplicity you can use css viewport dimensions. Something like this:

<div class="pre-scrollable" style="max-height: 75vh">
     <table>...</table>
</div>

where "75vh" is 75% of visible height.