Bootstrap 5 Grid Not Equaling 12 Column Width

Correct me if I am wrong, a bootstrap grid consists of 12 columns (width-wise [per the Grid System Documentation]). If I specify two columns within a fluid container (always width 100%), the first column col-md-3, and the second col-md-9. Why does my second column always get pushed underneath the first column? Shouldn't it be side by side?

        var dataSet = [
            ["Tiger Nixon", "System Architect", "Edinburgh", "5421", "2011/04/25", "$320,800"],
            ["Garrett Winters", "Accountant", "Tokyo", "8422", "2011/07/25", "$170,750"],
            ["Ashton Cox", "Junior Technical Author", "San Francisco", "1562", "2009/01/12", "$86,000"],
            ["Cedric Kelly", "Senior Javascript Developer", "Edinburgh", "6224", "2012/03/29", "$433,060"],
            ["Airi Satou", "Accountant", "Tokyo", "5407", "2008/11/28", "$162,700"],
            ["Brielle Williamson", "Integration Specialist", "New York", "4804", "2012/12/02", "$372,000"],
            ["Herrod Chandler", "Sales Assistant", "San Francisco", "9608", "2012/08/06", "$137,500"],
            ["Rhona Davidson", "Integration Specialist", "Tokyo", "6200", "2010/10/14", "$327,900"],
            ["Colleen Hurst", "Javascript Developer", "San Francisco", "2360", "2009/09/15", "$205,500"],
            ["Sonya Frost", "Software Engineer", "Edinburgh", "1667", "2008/12/13", "$103,600"],
            ["Jena Gaines", "Office Manager", "London", "3814", "2008/12/19", "$90,560"],
            ["Quinn Flynn", "Support Lead", "Edinburgh", "9497", "2013/03/03", "$342,000"],
            ["Charde Marshall", "Regional Director", "San Francisco", "6741", "2008/10/16", "$470,600"],
            ["Haley Kennedy", "Senior Marketing Designer", "London", "3597", "2012/12/18", "$313,500"],
            ["Tatyana Fitzpatrick", "Regional Director", "London", "1965", "2010/03/17", "$385,750"],
            ["Michael Silva", "Marketing Designer", "London", "1581", "2012/11/27", "$198,500"],
            ["Paul Byrd", "Chief Financial Officer (CFO)", "New York", "3059", "2010/06/09", "$725,000"],
            ["Gloria Little", "Systems Administrator", "New York", "1721", "2009/04/10", "$237,500"],
            ["Bradley Greer", "Software Engineer", "London", "2558", "2012/10/13", "$132,000"],
            ["Dai Rios", "Personnel Lead", "Edinburgh", "2290", "2012/09/26", "$217,500"],
            ["Jenette Caldwell", "Development Lead", "New York", "1937", "2011/09/03", "$345,000"],
            ["Yuri Berry", "Chief Marketing Officer (CMO)", "New York", "6154", "2009/06/25", "$675,000"],
            ["Caesar Vance", "Pre-Sales Support", "New York", "8330", "2011/12/12", "$106,450"],
            ["Doris Wilder", "Sales Assistant", "Sydney", "3023", "2010/09/20", "$85,600"],
            ["Angelica Ramos", "Chief Executive Officer (CEO)", "London", "5797", "2009/10/09", "$1,200,000"],
            ["Gavin Joyce", "Developer", "Edinburgh", "8822", "2010/12/22", "$92,575"],
            ["Jennifer Chang", "Regional Director", "Singapore", "9239", "2010/11/14", "$357,650"],
            ["Brenden Wagner", "Software Engineer", "San Francisco", "1314", "2011/06/07", "$206,850"],
            ["Fiona Green", "Chief Operating Officer (COO)", "San Francisco", "2947", "2010/03/11", "$850,000"],
            ["Shou Itou", "Regional Marketing", "Tokyo", "8899", "2011/08/14", "$163,000"],
            ["Michelle House", "Integration Specialist", "Sydney", "2769", "2011/06/02", "$95,400"],
            ["Suki Burks", "Developer", "London", "6832", "2009/10/22", "$114,500"],
            ["Prescott Bartlett", "Technical Author", "London", "3606", "2011/05/07", "$145,000"],
            ["Gavin Cortez", "Team Leader", "San Francisco", "2860", "2008/10/26", "$235,500"],
            ["Martena Mccray", "Post-Sales support", "Edinburgh", "8240", "2011/03/09", "$324,050"],
            ["Unity Butler", "Marketing Designer", "San Francisco", "5384", "2009/12/09", "$85,675"]
        ];

        $(document).ready(function () {
            $('#example').DataTable({
                data: dataSet,
                columns: [
                    { title: "Name" },
                    { title: "Position" },
                    { title: "Office" },
                    { title: "Extn." },
                    { title: "Start date" },
                    { title: "Salary" }
                ]
            });
        });

#newBTN, #updtBTN {
  background: #B3AB7D;
  padding: 10px;
  text-align: center;
  border-radius: 5px;
  color: white;
  font-weight: bold;
  margin: 0 auto;
}
#newBTN:visited, #updtBTN:visited {
  background: #B3AB7D;
  padding: 10px;
  text-align: center;
  border-radius: 5px;
  color: white;
  font-weight: bold;
  margin: 0 auto;
}

.button {
  background: #B3AB7D;
  padding: 10px;
  text-align: center;
  border-radius: 5px;
  color: white;
  font-weight: bold;
  margin: 0 auto;
}

.button:visited {
  background: #B3AB7D;
  padding: 10px;
  text-align: center;
  border-radius: 5px;
  color: white;
  font-weight: bold;
  margin: 0 auto;
}

#newBTN, #updtBTN {
  width: 300px;
}

#my-legend {
  width: 300px;
}
.my-legend .legend-title {
  text-align: left;
  margin-bottom: 5px;
  font-weight: bold;
  font-size: 90%;
}

.my-legend .legend-scale ul {
  margin: 0;
  margin-bottom: 5px;
  padding: 0;
  float: left;
  list-style: none;
}

.my-legend .legend-scale ul li {
  font-size: 80%;
  list-style: none;
  margin-left: 0;
  line-height: 18px;
  margin-bottom: 2px;
}

.my-legend ul.legend-labels li span {
  display: block;
  float: left;
  height: 16px;
  width: 30px;
  margin-right: 5px;
  margin-left: 0;
  border: 1px solid #999;
}

.my-legend .legend-source {
  font-size: 70%;
  color: #999;
  clear: both;
}

.my-legend a {
  color: #777;
}

<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <link rel="stylesheet" type="text/css"
        href="https://cdnjs.cloudflare.com/ajax/libs/twitter-bootstrap/5.0.1/css/bootstrap.min.css" />
    <link rel="stylesheet" type="text/css"
        href="https://cdn.datatables.net/1.10.25/css/dataTables.bootstrap5.min.css" />
    <link rel="stylesheet" type="text/css"
        href="https://cdn.datatables.net/buttons/1.7.1/css/buttons.bootstrap5.min.css" />
    <link rel="stylesheet" type="text/css"
        href="https://cdn.datatables.net/datetime/1.1.0/css/dataTables.dateTime.min.css" />
    <link rel="stylesheet" type="text/css"
        href="https://cdn.datatables.net/responsive/2.2.9/css/responsive.bootstrap5.min.css" />
    <link rel="stylesheet" type="text/css"
        href="https://cdn.datatables.net/rowgroup/1.1.3/css/rowGroup.bootstrap5.min.css" />
    <link href="https://code.jquery.com/ui/1.12.1/themes/smoothness/jquery-ui.css" rel="stylesheet" />

    <script type="text/javascript" src="https://code.jquery.com/jquery-3.3.1.min.js"></script>
    <script type="text/javascript"
        src="https://cdnjs.cloudflare.com/ajax/libs/twitter-bootstrap/5.0.1/js/bootstrap.bundle.min.js"></script>
    <script type="text/javascript" src="https://cdnjs.cloudflare.com/ajax/libs/jszip/2.5.0/jszip.min.js"></script>
    <script type="text/javascript" src="https://cdnjs.cloudflare.com/ajax/libs/pdfmake/0.1.36/pdfmake.min.js"></script>
    <script type="text/javascript" src="https://cdnjs.cloudflare.com/ajax/libs/pdfmake/0.1.36/vfs_fonts.js"></script>
    <script type="text/javascript" src="https://cdn.datatables.net/1.10.25/js/jquery.dataTables.min.js"></script>
    <script type="text/javascript" src="https://cdn.datatables.net/1.10.25/js/dataTables.bootstrap5.min.js"></script>
    <script type="text/javascript" src="https://cdn.datatables.net/buttons/1.7.1/js/dataTables.buttons.min.js"></script>
    <script type="text/javascript" src="https://cdn.datatables.net/buttons/1.7.1/js/buttons.bootstrap5.min.js"></script>
    <script type="text/javascript" src="https://cdn.datatables.net/buttons/1.7.1/js/buttons.html5.min.js"></script>
    <script type="text/javascript" src="https://cdn.datatables.net/buttons/1.7.1/js/buttons.print.min.js"></script>
    <script type="text/javascript"
        src="https://cdn.datatables.net/datetime/1.1.0/js/dataTables.dateTime.min.js"></script>
    <script type="text/javascript"
        src="https://cdn.datatables.net/responsive/2.2.9/js/dataTables.responsive.min.js"></script>
    <script type="text/javascript"
        src="https://cdn.datatables.net/responsive/2.2.9/js/responsive.bootstrap5.js"></script>
    <script type="text/javascript"
        src="https://cdn.datatables.net/rowgroup/1.1.3/js/dataTables.rowGroup.min.js"></script>
    <script src="https://momentjs.com/downloads/moment.min.js"></script>
</head>
<body>
<div class="container-fluid">
  
<div class="col-md-3">
  <div class="row p-3">
    <a href="#" class="button btn" id="newBTN" onclick="openDialog();">Create New Report</a>
  </div>
  <div class="row p-3">
    <a href="#" class="button btn" id="updtBTN" onclick="openEditForThisUserThisWeek();">Update Current Report</a>
  </div>
  <div class="row justify-content-center p-3">
    <div class='my-legend' id="my-legend" style="border: 1px solid black;">
      <div class='legend-title'>Color Code Values:</div>
      <div class='legend-scale'>
        <ul class='legend-labels'>
          <li><span style='background:#66b266;'></span>100 - 75 % Present</li>
          <li><span style='background:#ffff66;'></span>75 - 25 % Present</li>
          <li><span style='background:#ff6666;'></span>Less than 25% Present</li>
        </ul>
      </div>
    </div>
  </div>
</div>
<div class="col-md-6">
  <table id="example" class="display" width="100%"></table>
</div>
</div>

</body>
</html>

Solution

You're missing a div with the row class after your container-fluid div. That will help you with your case. In Bootstrap, after a container, if you will use cols, it is best to wrap them into a row class div.

var dataSet = [
            ["Tiger Nixon", "System Architect", "Edinburgh", "5421", "2011/04/25", "$320,800"],
            ["Garrett Winters", "Accountant", "Tokyo", "8422", "2011/07/25", "$170,750"],
            ["Ashton Cox", "Junior Technical Author", "San Francisco", "1562", "2009/01/12", "$86,000"],
            ["Cedric Kelly", "Senior Javascript Developer", "Edinburgh", "6224", "2012/03/29", "$433,060"],
            ["Airi Satou", "Accountant", "Tokyo", "5407", "2008/11/28", "$162,700"],
            ["Brielle Williamson", "Integration Specialist", "New York", "4804", "2012/12/02", "$372,000"],
            ["Herrod Chandler", "Sales Assistant", "San Francisco", "9608", "2012/08/06", "$137,500"],
            ["Rhona Davidson", "Integration Specialist", "Tokyo", "6200", "2010/10/14", "$327,900"],
            ["Colleen Hurst", "Javascript Developer", "San Francisco", "2360", "2009/09/15", "$205,500"],
            ["Sonya Frost", "Software Engineer", "Edinburgh", "1667", "2008/12/13", "$103,600"],
            ["Jena Gaines", "Office Manager", "London", "3814", "2008/12/19", "$90,560"],
            ["Quinn Flynn", "Support Lead", "Edinburgh", "9497", "2013/03/03", "$342,000"],
            ["Charde Marshall", "Regional Director", "San Francisco", "6741", "2008/10/16", "$470,600"],
            ["Haley Kennedy", "Senior Marketing Designer", "London", "3597", "2012/12/18", "$313,500"],
            ["Tatyana Fitzpatrick", "Regional Director", "London", "1965", "2010/03/17", "$385,750"],
            ["Michael Silva", "Marketing Designer", "London", "1581", "2012/11/27", "$198,500"],
            ["Paul Byrd", "Chief Financial Officer (CFO)", "New York", "3059", "2010/06/09", "$725,000"],
            ["Gloria Little", "Systems Administrator", "New York", "1721", "2009/04/10", "$237,500"],
            ["Bradley Greer", "Software Engineer", "London", "2558", "2012/10/13", "$132,000"],
            ["Dai Rios", "Personnel Lead", "Edinburgh", "2290", "2012/09/26", "$217,500"],
            ["Jenette Caldwell", "Development Lead", "New York", "1937", "2011/09/03", "$345,000"],
            ["Yuri Berry", "Chief Marketing Officer (CMO)", "New York", "6154", "2009/06/25", "$675,000"],
            ["Caesar Vance", "Pre-Sales Support", "New York", "8330", "2011/12/12", "$106,450"],
            ["Doris Wilder", "Sales Assistant", "Sydney", "3023", "2010/09/20", "$85,600"],
            ["Angelica Ramos", "Chief Executive Officer (CEO)", "London", "5797", "2009/10/09", "$1,200,000"],
            ["Gavin Joyce", "Developer", "Edinburgh", "8822", "2010/12/22", "$92,575"],
            ["Jennifer Chang", "Regional Director", "Singapore", "9239", "2010/11/14", "$357,650"],
            ["Brenden Wagner", "Software Engineer", "San Francisco", "1314", "2011/06/07", "$206,850"],
            ["Fiona Green", "Chief Operating Officer (COO)", "San Francisco", "2947", "2010/03/11", "$850,000"],
            ["Shou Itou", "Regional Marketing", "Tokyo", "8899", "2011/08/14", "$163,000"],
            ["Michelle House", "Integration Specialist", "Sydney", "2769", "2011/06/02", "$95,400"],
            ["Suki Burks", "Developer", "London", "6832", "2009/10/22", "$114,500"],
            ["Prescott Bartlett", "Technical Author", "London", "3606", "2011/05/07", "$145,000"],
            ["Gavin Cortez", "Team Leader", "San Francisco", "2860", "2008/10/26", "$235,500"],
            ["Martena Mccray", "Post-Sales support", "Edinburgh", "8240", "2011/03/09", "$324,050"],
            ["Unity Butler", "Marketing Designer", "San Francisco", "5384", "2009/12/09", "$85,675"]
        ];

        $(document).ready(function () {
            $('#example').DataTable({
                data: dataSet,
                columns: [
                    { title: "Name" },
                    { title: "Position" },
                    { title: "Office" },
                    { title: "Extn." },
                    { title: "Start date" },
                    { title: "Salary" }
                ]
            });
        });

#newBTN, #updtBTN {
  background: #B3AB7D;
  padding: 10px;
  text-align: center;
  border-radius: 5px;
  color: white;
  font-weight: bold;
  margin: 0 auto;
}
#newBTN:visited, #updtBTN:visited {
  background: #B3AB7D;
  padding: 10px;
  text-align: center;
  border-radius: 5px;
  color: white;
  font-weight: bold;
  margin: 0 auto;
}

.button {
  background: #B3AB7D;
  padding: 10px;
  text-align: center;
  border-radius: 5px;
  color: white;
  font-weight: bold;
  margin: 0 auto;
}

.button:visited {
  background: #B3AB7D;
  padding: 10px;
  text-align: center;
  border-radius: 5px;
  color: white;
  font-weight: bold;
  margin: 0 auto;
}

#newBTN, #updtBTN {
  width: 300px;
}

#my-legend {
  width: 300px;
}
.my-legend .legend-title {
  text-align: left;
  margin-bottom: 5px;
  font-weight: bold;
  font-size: 90%;
}

.my-legend .legend-scale ul {
  margin: 0;
  margin-bottom: 5px;
  padding: 0;
  float: left;
  list-style: none;
}

.my-legend .legend-scale ul li {
  font-size: 80%;
  list-style: none;
  margin-left: 0;
  line-height: 18px;
  margin-bottom: 2px;
}

.my-legend ul.legend-labels li span {
  display: block;
  float: left;
  height: 16px;
  width: 30px;
  margin-right: 5px;
  margin-left: 0;
  border: 1px solid #999;
}

.my-legend .legend-source {
  font-size: 70%;
  color: #999;
  clear: both;
}

.my-legend a {
  color: #777;
}

<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <link rel="stylesheet" type="text/css"
        href="https://cdnjs.cloudflare.com/ajax/libs/twitter-bootstrap/5.0.1/css/bootstrap.min.css" />
    <link rel="stylesheet" type="text/css"
        href="https://cdn.datatables.net/1.10.25/css/dataTables.bootstrap5.min.css" />
    <link rel="stylesheet" type="text/css"
        href="https://cdn.datatables.net/buttons/1.7.1/css/buttons.bootstrap5.min.css" />
    <link rel="stylesheet" type="text/css"
        href="https://cdn.datatables.net/datetime/1.1.0/css/dataTables.dateTime.min.css" />
    <link rel="stylesheet" type="text/css"
        href="https://cdn.datatables.net/responsive/2.2.9/css/responsive.bootstrap5.min.css" />
    <link rel="stylesheet" type="text/css"
        href="https://cdn.datatables.net/rowgroup/1.1.3/css/rowGroup.bootstrap5.min.css" />
    <link href="https://code.jquery.com/ui/1.12.1/themes/smoothness/jquery-ui.css" rel="stylesheet" />

    <script type="text/javascript" src="https://code.jquery.com/jquery-3.3.1.min.js"></script>
    <script type="text/javascript"
        src="https://cdnjs.cloudflare.com/ajax/libs/twitter-bootstrap/5.0.1/js/bootstrap.bundle.min.js"></script>
    <script type="text/javascript" src="https://cdnjs.cloudflare.com/ajax/libs/jszip/2.5.0/jszip.min.js"></script>
    <script type="text/javascript" src="https://cdnjs.cloudflare.com/ajax/libs/pdfmake/0.1.36/pdfmake.min.js"></script>
    <script type="text/javascript" src="https://cdnjs.cloudflare.com/ajax/libs/pdfmake/0.1.36/vfs_fonts.js"></script>
    <script type="text/javascript" src="https://cdn.datatables.net/1.10.25/js/jquery.dataTables.min.js"></script>
    <script type="text/javascript" src="https://cdn.datatables.net/1.10.25/js/dataTables.bootstrap5.min.js"></script>
    <script type="text/javascript" src="https://cdn.datatables.net/buttons/1.7.1/js/dataTables.buttons.min.js"></script>
    <script type="text/javascript" src="https://cdn.datatables.net/buttons/1.7.1/js/buttons.bootstrap5.min.js"></script>
    <script type="text/javascript" src="https://cdn.datatables.net/buttons/1.7.1/js/buttons.html5.min.js"></script>
    <script type="text/javascript" src="https://cdn.datatables.net/buttons/1.7.1/js/buttons.print.min.js"></script>
    <script type="text/javascript"
        src="https://cdn.datatables.net/datetime/1.1.0/js/dataTables.dateTime.min.js"></script>
    <script type="text/javascript"
        src="https://cdn.datatables.net/responsive/2.2.9/js/dataTables.responsive.min.js"></script>
    <script type="text/javascript"
        src="https://cdn.datatables.net/responsive/2.2.9/js/responsive.bootstrap5.js"></script>
    <script type="text/javascript"
        src="https://cdn.datatables.net/rowgroup/1.1.3/js/dataTables.rowGroup.min.js"></script>
    <script src="https://momentjs.com/downloads/moment.min.js"></script>
</head>
<body>
<div class="container-fluid">
<div class="row my-3">
<div class="col-md-3">
  <div class="row p-3">
    <a href="#" class="button btn" id="newBTN" onclick="openDialog();">Create New Report</a>
  </div>
  <div class="row p-3">
    <a href="#" class="button btn" id="updtBTN" onclick="openEditForThisUserThisWeek();">Update Current Report</a>
  </div>
  <div class="row justify-content-center p-3">
    <div class='my-legend' id="my-legend" style="border: 1px solid black;">
      <div class='legend-title'>Color Code Values:</div>
      <div class='legend-scale'>
        <ul class='legend-labels'>
          <li><span style='background:#66b266;'></span>100 - 75 % Present</li>
          <li><span style='background:#ffff66;'></span>75 - 25 % Present</li>
          <li><span style='background:#ff6666;'></span>Less than 25% Present</li>
        </ul>
      </div>
    </div>
  </div>
</div>
<div class="col-md-6">
  <table id="example" class="display" width="100%"></table>
</div>
</div>
</div>
</body>
</html>